JPH02179670A - Toner transfer device - Google Patents

Abstract

PURPOSE:To stabilize transfer by providing a plate on a down-stream side from the introduction side of a transfer belt within the discharging range of a corona charger on the side of the transfer belt opposite to a photosensitive body so that the plate may push up the transfer belt when the transfer belt is separated from the photosensitive body and pushing back the plate by the photosensitive body when the belt is in contact with the photosensitive body. CONSTITUTION:The plate 30 is provided on the downstream side from the introduction side of the transfer belt within the discharging range of the transfer charger 23 and the belt 21 is pushed up by a spring 31 so as to prevent the looseness and meandering caused by the rotation of driving rollers 29 and 28. When a transfer part is pressed to the photosensitive body 15 to transfer a color toner image on the photosensitive body on the paper 19, the transfer belt 21 is pressed against the photosensitive body 15 by the plate 30 to remove the wrinkle of the belt and transfer the uniform toner image. Furthermore, a conductive layer 32 is provided on the plate 30 on the corona charger side and bias voltage 33 having opposite polarity to that of the transfer corona charger is applied on the conductive layer, so that a phenomenon that the transfer starts before the photosensitive body 15 is in contact with paper and the toner image is scattered is suppressed and the stable good toner image is transferred.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a toner image transfer device that can be used in a hard copy device such as a copying machine or a printer.

2. Description of the Related Art Currently, in electrophotographic devices widely used in copying machines and laser printers, after an electrostatic latent image is written on an electrostatic latent image carrier such as an electrophotographic photoreceptor, charged toner is A well-known method is to electrostatically adhere and develop the toner, and then perform corona transfer onto plain paper using a corona charger to which a voltage of opposite polarity to that of the toner is applied, thereby obtaining a toner image on the plain paper.

As one such example, the inventors filed a patent application in 1983-1965.
There is a toner transfer device proposed in No. 86.

The outline will be explained using FIG. 2.

The developing device 1.2.3 is a non-contact type non-magnetic one-component developing device that uses a direct current electric field to scatter the toner, and the toner is charged by friction with a conductive fur brush 4.5.6 that is in contact with the developing roller. A thin layer of toner is formed by a blade 10.11.12 on an aluminum developer roller 7.8.9. Developing device 1 has yellow (Y), developing device 2
contains magenta (M) insulating toner, and the developing device 3 contains cyan (C) insulating toner. The black developing device 13 is a contact type developing device containing a two-component developer consisting of an insulating toner and a magnetic carrier, which is widely used in electrophotographic devices. The developing devices were disposed facing each other around the photoreceptor 15 with a constant gap between the developing roller 7, 8, 9, 14 and the photoreceptor 15. Each developing device is attached with a separation mechanism that brings it close to the photoreceptor 15 during development and away from it when not developing.

An amorphous 5e-Te photoreceptor drum 15 is used as a photoreceptor, and is charged to a charging potential of +900V by a charger 16. Next, the semiconductor laser 17 is caused to emit light to expose the photoreceptor 15 to a negative black signal to form an electrostatic latent image. After the latent image is reversely developed by the black developing device 13 in a developing state in which +eoov is applied to the developing roller 14 to form a black toner image, the -degree photoreceptor 15 is neutralized by the AC corona charger 18 . next,
The photoreceptor 15 is again charged to +600V by the corona charger 16. Thereafter, the photoreceptor 15 is exposed to signal light corresponding to yellow by the semiconductor laser 17 to form a yellow electrostatic latent image. Next, apply this photoreceptor to a developing roller at +600V.
A yellow toner image is formed by passing through a yellow developing device 1 in a developing state to which . next,
The photoreceptor 15 is neutralized by an AC corona charger 18, and the photoreceptor 15 is charged again to +810V by the corona charger 16. Thereafter, a semiconductor laser 17 is used to expose a signal light corresponding to magenta to form a magenta electrostatic latent image.

Next, the photoreceptor 15 is passed through a yellow developing device 1 in a non-developing state and a magenta developing device 2 in a developing state in which +8 ooV is applied to the developing roller 8 to form a magenta toner image. Thereafter, the photoreceptor 15 is passed through the cyan developer 3 and the black developer 13 in a non-developing state. Next, the photoreceptor 15 is neutralized by the AC corona charger 18, and the photoreceptor 15 is charged to +850V again by the corona charger 16. Thereafter, a semiconductor laser 17 is used to expose the semiconductor laser 17 to signal light corresponding to cyan to form a cyan electrostatic latent image. Next, the photoreceptor 15 is passed through a yellow developer 1 in a non-developing state, a magenta developer 2 in a non-developing state, and a cyan developer 3 in a developing state in which +830V is applied to the developing roller 9 to form a cyan toner image on the photoreceptor. Complete the color image on 15.

The plain paper 19 is conveyed on the transfer belt 21 while being in contact with a stainless steel fur brush 20 to which a voltage of +1 kV is applied, and is passed between the paper adsorption charger 22 and brought into close contact with the transfer belt 21. After the color toner image obtained on the photoreceptor 15 is transferred to this paper 19 by a transfer charger 23, the paper is charged by a paper separation charger 24, the paper is separated from the transfer belt 21, and a positive charger is used to charge the paper. 25 and a negative charger 26 to be charged.
Further, the image is thermally fixed by a fixing device 27.

Problems to be Solved by the Invention In order to transfer multiple layers of color toner images on a photoreceptor onto paper in one go, a transfer mechanism with higher precision than the conventional transfer of black and white images is required. Become. This is because the amount of charge of the toner on the photoreceptor differs for each color, so if, for example, the degree of contact between the photoreceptor and the paper changes even slightly, the color image will be transferred unevenly.

In the corona transfer method shown in the conventional example, since the transfer belt has rubber elasticity, the driving roller 2 as shown in FIG.
It was found that when the belt was wavy between 8 and 29, uniform transfer was not possible.

Even if you increase the tension of the transfer belt, in a high temperature environment,
While the belt is separated from the photoreceptor during image formation, the belt stretches, causing the belt to meander or sag.

FIG. 4 is an enlarged view of the transferred portion of FIG. 2. When the transfer belt is brought into pressure contact with the photoreceptor, if an attempt is made to increase the tension of the belt using only the drive shafts 28 and 29 to increase the degree of adhesion to the photoreceptor, an extremely strong tension will be generated in the direction of the arrow shown in the figure. If used for a long time, the material of the transfer belt will be damaged. Also, the belt rotation drive shaft 28.29
Even if a slight vibration from the rubber belt was transmitted to the transfer belt, the vibration was amplified by the rubber belt and caused the belt to move up and down, which immediately caused uneven transfer.

In view of the above, the present invention provides a device for corona-transferring a color toner image recorded on an electrostatic image carrier onto a photoreceptor, by increasing the degree of close contact between the photoreceptor and the transfer belt, so as to ensure stable operation at all times. An object of the present invention is to provide a toner transfer device capable of transferring toner.

Means for Solving the Problems The present invention is a toner transfer device for a color electrophotographic device that forms a color toner image on a photoreceptor by repeating charging, exposure, and reversal development steps using toner of multiple colors. , comprising the photoconductor carrying the toner image, a transfer belt in contact with the photoconductor, and a corona charger located on the back side of the transfer belt and applying a voltage of opposite polarity to the toner image, A transfer paper is sandwiched between the photoreceptor and the transfer belt at a contact position between the photoreceptor and the transfer belt, and the transfer belt is a belt having rubber elasticity, and the transfer belt is configured to hold the photoreceptor during transfer. The transfer belt is configured to be in contact with the body and separate from the photoreceptor during image formation on the photoreceptor, and the transfer belt is disposed on a side opposite to the photoreceptor, and the corona charger a plate-like member that extends downstream from the transfer belt introducing side and presses the transfer belt within a discharge range of the transfer belt, and when the transfer belt is separated from the photoreceptor, the plate-like member In the toner transfer device, the belt is pushed up, and when the transfer belt contacts the photoreceptor, the plate member is pushed back toward the corona zone N by the photoreceptor.

Operation The structure shown in FIG. 5 is the structure of the improved transfer section of the present invention. Here, a color image is currently being formed on the photoreceptor, and the transfer belt is separated from the photoreceptor. At this time, a plate-like member 31 is provided within the discharge range of the transfer charger 23 and is configured to extend downstream from the transfer belt introduction side and press the transfer belt. , push up the transfer belt 21. Even if the rotary drive rollers 29 and 21 are rotated in such a state, the belt does not become loose at all, and the belt does not meander or wrinkle.

FIG. 6 shows the improved transfer section shown in FIG.
5 and press the color toner image on the photoreceptor 15 onto the paper 19.
This figure shows the state when the image is transferred to the image. At this time, since the transfer belt 21 and the photoreceptor 15 are pressed against each other by the plate-like member 30, wrinkles on the transfer belt as shown in FIG. 3 described above do not occur, and a uniform color toner image is transferred. becomes possible.

In addition, as shown in FIG. 7, a conductive layer 32 is provided on the corona charger side of this plate member 3°, and a bias voltage 33 of opposite polarity to the voltage applied to the transfer corona charger is applied to this conductive layer. Then, the transfer starts before the photoreceptor 15 comes into close contact with the paper, and the phenomenon of toner image scattering can be suppressed, and more stable and beautiful toner image transfer becomes possible.

Examples Photoreceptors used in the present invention include electrophotographic photoreceptors in which a film of a photoconductive substance such as amorphous selenium, zinc oxide, or polyvinylcarbazole is formed on a conductive material such as aluminum.

For example, the transfer belt used for the transfer belt includes:
An insulating belt made of fluorinated ethylene resin, polyester resin, glass fiber, or the like is used. moreover,
A belt is used in which a layer of a high-resistance material such as polytetrafluoroethylene or polyethylene terephthalate is coated on the surface of conductive rubber in which carbon black or the like is dispersed. At this time, if the transfer belt has rubber elasticity, it will come into close contact with the plate-like member without any gaps, and the transfer performance will be further improved. If the conductive layer of this transfer belt is made completely conductive, it will block the transfer electric field and the toner image cannot be transferred.
It is desirable that the resistance value range is from 104 to IQlllΩQm. Also, the thickness of the transfer belt is 200μ
A range of m to 2 mm is desirable.

It is desirable to use a dielectric material that has good slippage with the transfer belt for the plate-like member. Such dielectric materials include polyester resin, ABS resin, styrene resin, polyacetal, Bakelite, vinyl chloride, polyoxymethylene,
There are alumina ceramics, etc.

In addition, a conductive layer is provided on the corona charger side of this plate-shaped member,
By applying a bias voltage with the opposite polarity to the voltage applied to the transfer corona charger to this conductive layer, the transfer starts before the photoreceptor comes into close contact with the paper, and it is possible to prevent the toner image from scattering, resulting in a more stable and beautiful toner. Image transfer becomes possible.

In the embodiments described below, a dry toner is used as the toner to be transferred, but the same effect can be obtained even if a wet toner is used.

Hereinafter, specific embodiments of the present invention will be described in more detail.

Specific example 1 A color image was formed using the apparatus shown in FIG.

The structure of the transfer belt 34 is a Teflon foot on the surface of a conductive rubber belt in which carbon black is dispersed, and its resistance value is toeΩcm1 and its thickness is 1mm.
It is. The developing units 35, 36, and 37 are non-contact, non-magnetic, single-component developing units that use a DC electric field to scatter the toner.
The toner is sent to the developing roller side by a conductive fur brush 41, 42, 43 that is in contact with the developing roller, and charged by friction, and then transferred onto an aluminum developing roller 44, 45, 46 by a blade 47, 48, 49. The structure is such that it forms a thin layer of Yellow (Y) is in the developing device 35,
The developing device 36 contains magenta (M) insulating toner, and the developing device 37 contains cyan (C) insulating toner. The black developing device 50 is
This is a contact type developer containing a two-component developer consisting of an insulating toner and a magnetic carrier, which is widely used in electrophotographic devices.

Toner is fed into the developing device 50 from the outside by a toner supply coil 51, the developer is mixed with carrier by a stirring blade 52, and further supplied to a developing roller 54 having a built-in magnet roller by a developer supply blade 53. Ru. Each developing device was disposed around the photoreceptor 55 so as to face each other with a constant gap (development gap) between the developing roller 44, 45, 46, 54 and the photoreceptor 55. Each developing device is brought close to the photoreceptor 55 during development, and is separated from the photoreceptor 55 during non-development, with a separation mechanism 56.
57.58.59 are installed.

The specifications and development conditions of the black developing device 50 and the physical properties of the toner are shown below.

・Developer specifications and development conditions Diameter of developing roller 54: 22 mm Peripheral speed of developing roller 54: 320 mm/s Thickness of developer layer on developing roller 54: 400 μm Developing roller 5
Rotation direction of 4: Opposite direction (same traveling direction) as the photoreceptor 55 Development gap (gap between the developing roller surface and the photoreceptor surface): 3008 m during development, 2 mm when not developed ・Developer physical properties Developer type Average of carrier Particle size Carrier type: Tefrotoner charge Toner average particle size: Two-component developer of toner and carrier: Approx. 50 μm Coated ferrite: +15 μC/g: 12 μm Toner relative dielectric constant: Approx. 2 Yellow ψ magenta/cyan developer The specifications, development conditions, and physical properties of the toner are shown below.

・Developer specifications and development conditions Development roller diameter: 20mm Development roller peripheral speed: 160mm/s Development roller rotation direction
: Opposite direction (same traveling direction) as the photoreceptor 55 Toner 1 on the current t roller! Thickness: 30 μm Development gap (gap between developing roller surface and photoreceptor surface): 150 μm during development 1 2 mm when not developing Φ Physical properties of toner Toner charge amount: +3 μC/g average particle diameter
: 12 μm Relative permittivity : Approximately 2 The photoreceptor was an amorphous 5e-Te photoreceptor drum 55 with a diameter of 152.8 mm (photosensitive layer thickness 63 μm1, relative permittivity of 7, functionally separated selenium sensitized to long wavelengths in the infrared region). Photoreceptor, half-decreased exposure amount at wavelength 790 nm: 0, 8 μJ/c
ll12) and rotated at a circumferential speed of 180 mm/s.

This photoreceptor 55 was charged to a charging potential of +900 V by a charger 60 (Scorotron charger, corona voltage: +7 kV1, grid voltage: 1 kV). Next, wavelength 790n
The semiconductor laser 61 of m was made to emit light for exposure. At this time,
The light intensity on the photoreceptor surface was N 1.5 mW. Using this semiconductor laser 61, a negative black signal was exposed onto the photoreceptor 55 to form an electrostatic latent image. The black developing device 5 is in a state where +600V is applied to the developing roller 54 to develop the latent image.
0 to form a black toner image, the -degree photoreceptor 55 is charged with an AC corona charger 62 (applied AC voltage: 4.
Static electricity was removed at 5kVrms, DC bias component; +200V).

Next, corona charger 6o again (Scorotron charger, corona voltage: +7kV, grid voltage: +800V)
The photoreceptor 55 is charged to +6ooV.

Thereafter, the photoreceptor 55 was exposed to signal light corresponding to yellow by the semiconductor laser 61 to form a yellow electrostatic latent image. Next, this photoreceptor is passed through a yellow developing device 35 in a developing state in which +600V is applied to the developing roller 44, a magenta developing device 36 in a non-developing state, a cyan developing device 37, and a black developing device 50 to form a yellow toner image. was formed. Next, this photoreceptor 55 is charged with an AC corona charger 62 (applied AC voltage: 4, 5 kVrms1 DC bias component; +
200 V), and the photoreceptor 55 was charged again to +810 V by a corona charger 60 (Scorotron charger, corona voltage: +7 kVs, grid voltage: +940 V). Thereafter, a semiconductor laser 61 was used to expose signal light corresponding to magenta to form a magenta electrostatic latent image. Next, the photoreceptor 55 was passed through a yellow developing device 35 in a non-developing state and a magenta developing device 36 in a developing state in which +5 oov was applied to the developing roller 45 to form a magenta toner image. Thereafter, the photoreceptor 55 is transferred to the cyan developer 37 in a non-developing state.
and a black developing device 50. Next, the photoreceptor 55 is charged with an AC corona charger 62 (applied AC voltage: 4.5 kVrms).
, DC bias component; +200V), and the photoreceptor 55 was charged again to +850V by the corona charger 60. Thereafter, a signal light corresponding to cyan was exposed using a semiconductor laser θ1 to form a cyan electrostatic latent image. Next, the photoreceptor 55 is passed through a yellow developer 35 in a non-developing state, a magenta developer 36 in a non-developing state, and a cyan developer 37 in a developing state in which +830V is applied to the developing roller 46 to form a cyan toner image on the photoreceptor. I completed a color image on 55.

The plain paper 63 is conveyed on the transfer belt 34 while being in contact with a stainless steel fur brush 64 to which a voltage of +1 kV is applied, and is passed between the paper adsorption charger 65 (applied voltage: -6 kV) and transferred to the transfer belt. I placed it in close contact with 34.

The transfer charger 66 includes a 2 m thick ABS resin in front of the corona discharge section and on the upstream side in the direction of movement of the transfer belt.
A plate-like member 67 of m is attached, and the transfer belt 34 is pushed up by a spring 68.

Thereafter, the transfer belt 34 was brought into pressure contact with the photoreceptor 55 by a push-up mechanism 69, and the color toner image obtained on the photoreceptor 55 was transferred onto paper 63 by a transfer charger 66 (applied voltage: -6 kV).

At this time, since the transfer belt 34 was pushed up by the plate member 67, the transfer belt 34 did not become loose, the belt did not meander or wrinkle, and the color toner image was transferred uniformly.

After that, the paper is charged by the paper separation charger 70 (applied voltage: -6 kV), and then the paper 63 is separated from the transfer belt 34, and the positive charger 71 (applied voltage; +8 kV) and the negative charger 72 (applied voltage; The toner was charged by passing between a pair of chargers (6 kv), and then thermally fixed by a fixing device 73.

On the other hand, after the transfer, the surface of the photoreceptor 55 is exposed to corona using an AC corona charger 62 (applied AC voltage: 4.5 kVrms1 DC bias component: +800V).
The static electricity was removed. Thereafter, a conductive fur brush cleaner 74 (fur made by dispersing carbon black in rayon fibers and having a specific resistance of 105 Ωcm wrapped around a stainless steel rod) to which a voltage of -350 V was applied was brought into pressure contact with the photoreceptor 55 for cleaning.

As a result, all of the black, yellow, magenta, and cyan toners were uniformly transferred to the paper, resulting in a clear image. At this time, the transfer belt did not wrinkle or meander.

Specific Example 2 Using the color electrophotographic apparatus shown in FIG. 1, an experiment was conducted in which the plate-like member of the transfer section was replaced with a plate-like member having a conductive electrode shown in FIG.

Aluminum foil was used as the conductive electrode 32, and a bias voltage 33 of +500V was applied.

The process of forming a color image on the photoreceptor was exactly the same as in the specific example.

As a result, the phenomenon of the toner image scattering due to transfer starting before the photoreceptor came into close contact with the paper was suppressed, and a more stable and beautiful color toner image was obtained.

Effects of the Invention According to the present invention, in a device that performs corona transfer of a color toner image recorded on an electrostatic image carrier onto a photoreceptor, the degree of adhesion between the photoreceptor and the transfer belt is increased to ensure stable transfer at all times. A toner transfer device is obtained that can perform the following steps.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of a color electrophotographic apparatus using a toner transfer device according to the present invention, FIG. 2 is an explanatory diagram of an electrophotographic apparatus including a conventional transfer device, and FIGS. The figure is an explanatory diagram showing the problems of the electrophotographic device shown in FIG. 2, FIGS. 5 and 6 are block diagrams showing an example of embodying the present invention, and FIG. 7 is a diagram showing another embodiment of the present invention. It is a block diagram which shows an example. 34...Transfer belt, 35...Yellow developer, 36
...Magenta developer, 37...Cyan developer, 50
...Black developer, 55...Photoreceptor, 60...Corona charger, 61...Semiconductor laser, 65...Adsorption corona charger, 66...Transfer charger, 67... Plate member, 68... spring, 73... heat fixing device. 74... Conductive fur brush. Name of agent: Patent attorney Shigetaka Awano

Claims (5)

[Claims] (1) A transfer belt that contacts a photoconductor that forms and carries a color toner image by repeating charging, exposure, and reversal development processes using toner of multiple colors; a corona charger to which a voltage of opposite polarity is applied, a transfer paper is sandwiched between the photoreceptor and the transfer belt at a contact position between the photoreceptor and the transfer belt, and the toner image is corona transfer, the transfer belt contacts the photoreceptor during transfer, the transfer belt separates from the photoreceptor during image formation on the photoreceptor, and is disposed on the opposite side of the transfer belt from the photoreceptor. a plate-like member that is provided and extends downstream from the transfer belt introduction side within the discharge range of the corona charger and presses the transfer belt, when the transfer belt is separated from the photoreceptor; , wherein the plate-like member pushes up the transfer belt, and when the transfer belt contacts the photoreceptor, the plate-like member is pushed back toward the corona charger by the photoreceptor. Transfer device. (2) The toner transfer device according to claim 2, wherein the transfer belt is a belt having a high resistance material layer formed on the surface of conductive rubber. (3) The toner transfer device according to claim 1 or 2, wherein the transfer belt is a belt having rubber elasticity. (4) The toner transfer device according to claim 1, wherein the plate-like member is a dielectric material. (5) having a conductive layer on the corona charger side of the plate member;
5. The toner transfer device according to claim 4, wherein a bias voltage is applied to the conductive layer.