JPH01265266A - Image forming method - Google Patents

Abstract

PURPOSE:To transfer a high contrast image by triboelectrifying photoconductive toner, exposing an image onto a toner layer formed by impressing a bias voltage between a conductive base and a toner holder and removing the exposed toner by means of bias impression. CONSTITUTION:A carrier 3 triboelectrifies the photoconductive toner 1 to minus, and a magnetic brush is brought into contact with the conductive base 7. Then the bias voltage 6 is impressed to make the photoconductive toner 1 more fine on the photoconductive base 7. Next, a writing head 7 directly exposes an image onto the toner layer, and the exposed conductive toner layer is brought into contact with a removing roller 11. Electric charges of polarity opposite from triboelectrified charges are injected with the aid of the bias voltage 12 impressed between a conductor 10 and the conductive base 7 to attach to an insulating body 9. The photoconductive toner which turns into a visible image is transferred onto the conductive base 7 by projecting plus charges at the rear of a transfer sheet 15 through a transfer charger 16. In such a way, a high contrast image free of base fogging can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image forming method using photoconductive toner.

[Prior Art] A conventional image forming method using a photoconductive toner does not use a photoreceptor and can perform exposure and development at the same time.

Many proposals have been made to date because it has advantages such as easy colorization. For example, JP-A-60-
The method proposed in No. 138566 involves forming a photoconductive toner layer negatively charged by a carrier on the entire surface of a transparent conductive hollow rotating substrate using a magnetic brush.
The substrate is imagewise exposed from the inside, a bias voltage is applied to positively charge the exposed area, and the toner in the exposed area is transferred to plain paper using an electric field.

[Problems to be Solved by the Invention] However, in the conventional image forming method, when photoconductive toner, which has been exposed to light and has a low resistance, is transferred by electric field to plain paper,
It is strongly affected by humidity, making it impossible to obtain sufficient image density.Furthermore, unexposed photoconductive toner also comes into contact with the transfer paper during transfer, resulting in images with a lot of blurring. are doing.

Therefore, it is an object of the present invention to provide an image forming method that uses photoconductive toner and can provide image quality with no background image and high contrast ratio without selecting a transfer paper.

[Means for Solving the Problems] The image forming method of the present invention is an image forming method using a photoconductive toner, and includes (a) a step of tribocharging the photoconductive toner, (b) a step of triboelectrically charging the photoconductive toner, and (b) a step of triboelectrically charging the photoconductive toner. forming a photoconductive toner layer on the conductive substrate by applying a bias voltage between the photoconductive toner carrier; (C) imagewise exposing the photoconductive toner layer; (d) exposure. a step of transferring and removing the photoconductive toner onto an insulator by applying a bias to create a visible image; (e) a step of transferring the visualized photoconductive toner to a recording paper; (f) a step of transferring the visualized photoconductive toner to a recording paper; The method is characterized in that it includes a step of fixing the photoconductive toner transferred to the photoconductive toner using at least one of heat and pressure.

[Operation] Since the triboelectrically charged photoconductive toner is insulative, it forms a thin layer in response to the charge induced on the conductive substrate by the bias voltage. When this thin layer is subjected to imagewise exposure, the photoconductive toner exposed to light becomes less resistive and loses its triboelectric charge. After this, when it is brought into contact with an insulator and a bias voltage is applied at the same time, it is irradiated with light, and the photoconductive toner whose resistance has been reduced is injected with a charge opposite to the triboelectric charge, which adheres to the insulator and is removed from the conductive substrate. . The photoconductive toner corresponding to the image remaining on the conductive substrate is insulative and can be easily electrostatically transferred.

Hereinafter, the details of the present invention will be shown by examples.

[Example 1 FIG. 1 shows a schematic diagram of the image forming method according to the present invention.

A two-component magnetic brush using a carrier was used to triboelectrically charge the photoconductive toner.

Note that the frictional charging method is not limited to the two-component magnetic brush method. Using a two-component magnetic brush developer consisting of a photoconductive toner 1, a toner hopper 2, a carrier 3, a magnetic roller 4, and a sleeve 5, the photoconductive toner was negatively charged by friction with the carrier. (The polarity of friction charging is either positive or negative depending on the characteristics of the photoconductive toner.) Next, the magnetic brush is brought into contact with the conductive substrate 7 and a bias voltage 6 is applied to transfer the photoconductive toner onto the conductive substrate. It has been made even more dense. At this time, direct current was used as the bias voltage 6, and the voltage was set to 500 V or less.

Next, the toner layer was directly exposed imagewise by the writing head 8 . As the writing head 8, a semiconductor laser was used. The exposure head is not limited to a laser, and LEDs, LC3, etc. can also be used. Furthermore, by making the conductive substrate transparent, the exposure head can be positioned from the back side of the substrate.

The exposed photoconductive toner layer is brought into contact with the removal roller 11, and a bias voltage 12 applied between the conductor 10 and the conductive substrate 7 causes a triboelectric charge to be generated on the exposed photoconductive toner, which has been made low in resistance. can be attached to the insulator 9 by injecting opposite charges.

The attached photoconductive toner is removed by a cleaning blade 13 into a toner container 14 . The removed photoconductive toner can be returned to the toner hopper 2 and used again for image formation. Via 7° Voltage 12 is DC,
I set it to 300v or less. Further, as the insulator 9, a material with low surface energy, such as Teflon (Dupont), silicone rubber, polyamide, etc., is used.

As a result, the unexposed photoconductive toner retains its initial negative triboelectric charge, and adhesion forces such as van der Waals forces can be minimized, so that it does not adhere to the insulator 9.

Next, the exposed photoconductive toner is removed and the photoconductive toner visualized on the conductive substrate 7 comes into contact with the transfer paper 15, and is irradiated with a positive charge from behind by the transfer charger 16 and coulombized. Transfer to transfer paper using force. In this case, the transfer is not limited to electrostatic transfer, but also electric field transfer,
Adhesive transfer, heat pressure transfer, magnetic transfer, etc. can also be used.

The photoconductive toner transferred to the transfer paper is transferred to a heat fixing roller 17.
is fixed on the transfer paper. The fixing method is pressure,
It is also possible to use a combination of heat and pressure.

FIGS. 2(a) and 2(b) show cross-sectional views of the photoconductive toner used in this example. The same figure (a) shows colorant 20 and additive 2.
This is a photoconductive toner in which a layer of a photoconductive agent 18 dispersed in the resin is coated on toner nuclei in which the photoconductive agent 18 and the colorant 2 are dispersed in the binding resin 19.
0, a photoconductive toner in which additive 21 was dispersed in a binding resin. Note that the additives refer to fluidity improvers and charge control agents. As the photoconductive agent, known zinc oxide, titanium oxide, phthalocyanine, etc. are used. In some cases, a sensitizing dye is adsorbed onto the photoconductive agent to sensitize the wavelength corresponding to the writing head. As the binding resin, thermoplastic resins such as acrylic resins and polyester resins, and wax-based resins are used. As a method for producing the photoconductive toner, these raw materials were dispersed in a solvent and a spherical toner having an average particle size of 9 microns was produced by a spray drying method. The photoconductive toner used in this example had a dark resistance of 1
It is preferable that the resistance is 0.015 Ωcm or more, and the bright resistance is 10” Ω.m or less.

When an image was formed using photoconductive toner using the image forming method of the present invention, a good image with no blurring and a high contrast ratio could be obtained on plain paper.

[Example 2] FIG. 3 shows a schematic diagram of an image forming method according to another example of the present invention. A two-component magnetic brush was used as in Example 1 to triboelectrically charge the photoconductive toner. Note that the frictional charging method is not limited to the two-component magnetic brush method. Elements similar to those in Example 1 are designated by the same numbers. Using a two-component magnetic brush developer consisting of a photoconductive toner 1, a toner hopper 2, a carrier 3, a magnetic roller 4, and a sleeve 5, the photoconductive toner was negatively charged by the carrier. (The polarity of friction charging is either positive or negative depending on the characteristics of the photoconductive toner.

) Next, a magnetic brush was brought into contact with the conductive substrate 7 and a bias voltage was applied to form a multilayer fine layer of photoconductive toner on the conductive substrate. At this time, direct current was used as a bias voltage, and the voltage was set to 600V or less.

Next, the toner layer was directly image exposed by the writing head 31. The writing head 31 is an LCS (Liquid Crystal 5hu) using a liquid crystal shutter.
tter (liquid crystal shutter) head was used. The exposure head is not limited to the LCS head, and lasers, LEDs, etc. can also be used.

Furthermore, by making the conductive substrate 7 transparent, the exposure head can be positioned from the back side of the substrate.

The exposed photoconductive toner layer is brought into contact with the remover 34 and the bias voltage 12 applied between the conductive roll 33 and the conductive substrate 7 causes a triboelectric charge to be applied to the exposed photoconductive toner which has been made low in resistance. An opposite charge can be injected and attached to the insulating belt 32. The attached photoconductive toner can be returned to the toner hopper 2 and used again for image formation. The bias voltage 12 is DC, 300
I made it so that it is below V. Further, as the insulating belt 32, a material with low surface energy such as Teflon (Dupont), silicone rubber, polyamide, etc. is used.

As a result, the unexposed photoconductive toner retains its initial negative triboelectric charge, and adhesion due to van der Waals forces or the like can be minimized, so that it does not adhere to the insulating belt 32.

Furthermore, by slowing down the rotational speed of the insulating belt to within 20% of the rotational speed of the conductive substrate 7, all of the photoconductive toner that has been exposed in multiple layers and has a low resistance can be deposited on the insulating belt. can. It should be noted that the multilayer is preferably five or less layers; if it is six or more layers, the adhesion to the insulating belt will not be removed sufficiently, and the exposed photoconductive toner will remain on the conductive substrate 7, resulting in a decrease in contrast. It ends up.

Next, the exposed photoconductive toner is removed and the photoconductive toner visualized on the conductive substrate 7 comes into contact with the transfer paper 15, and is irradiated with a positive charge from behind by the transfer charger 16 and coulombized. Transfer to transfer paper using force. In this case, the transfer is not limited to electrostatic transfer, but also electric field transfer,
Adhesive transfer, heat pressure transfer, magnetic transfer, etc. can also be used.

The photoconductive toner transferred to the transfer paper is transferred to the pressure fixing roller 3.
4, the image is fixed on the transfer paper. Other fixing methods that can be used include heat and a combination of heat and pressure.

The photoconductive toner used in this example was the same as that used in Example 1.

When an image was formed according to this example, there was no blurring, the contrast ratio was high, the image density was 0°D, and the value was 1.
A good image of 4 or higher was able to be obtained on plain paper.

Although the embodiments have been described above, the present invention can be applied not only to the above embodiments but also to multi-color and full-color image forming methods.

[Effects of the Invention] As described above, according to the present invention, in an image forming method using a photoconductive toner, (a) triboelectrically charging the photoconductive toner; (b) a step of tribocharging the photoconductive toner; forming a photoconductive toner layer on the conductive substrate by applying a bias voltage between the photoconductive toner carrier; (C) imagewise exposing the photoconductive toner layer; (d) exposure. (e) Transferring the visualized photoconductive toner onto recording paper; (f) Recording. The process of fixing the photoconductive toner transferred to paper using at least one of heat and pressure produces a clear image with no blurring, high contrast ratio, and image density of ○, D, value = 1.4 or more. images can be formed on plain paper. If this is applied to a device, a very simple device can be created, and an innovative image forming device with low initial and running costs and maintenance free can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the image forming method of the present invention, FIGS. 2(a) and (b) are cross-sectional views of the photoconductive toner used in the image forming method of the present invention, and FIG. 3 is a schematic diagram showing the image forming method of the present invention. FIG. 3 is a schematic diagram illustrating an image forming method according to another embodiment. 1 Photoconductive toner 6 Conductive substrate 7 Writing head 8 Insulator 9 Conductor 11 Removal roller 12 Bias voltage 15 Transfer paper 18 Photoconductive agent 19 Binding resin 20 Coloring agent 21 Additives and more Applicant Attorney for Seiko Epson Corporation Master Kisanbe Suzuki (and 1 other person)

Claims (1)

[Claims] An image forming method using a photoconductive toner, comprising: (a) triboelectrically charging the photoconductive toner; (b) between a conductive substrate and a photoconductive toner carrier; (c) imagewise exposing the photoconductive toner layer to light by applying a bias voltage; (d) applying a bias voltage to the exposed photoconductive toner; (e) Transferring the visualized photoconductive toner to recording paper; (f) Heat or heat the photoconductive toner transferred to the recording paper. An image forming method comprising the step of fixing using at least one of pressure.