JPH04307574A - wet recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to recording paper, overhead projector film (hereinafter referred to as OHP film)
The present invention relates to a wet type recording device that forms an image on a slide film or the like using a wet type developer formed by dispersing charged toner particles in an insulating carrier liquid.

0002

2. Description of the Related Art In a conventional wet type recording apparatus, an electrostatic latent image carrier passes over a plate-shaped electrode containing developer, and toner is adsorbed onto the electrostatic latent image carrier. -5146
6 etc.) are known. In addition, the developer is discharged from a groove-shaped opening provided in the electrode plate that faces the electrostatic latent image carrier through a small gap, and responds to the electric field created by the electrostatic latent image carrier and the electrode plate. A method in which charged toner particles are attached to form an image on an electrostatic latent image carrier (Utility Model No. 63-84)
No. 394, etc.) are known.

The toner image thus obtained on the electrostatic latent image carrier is electrostatically transferred to a recording medium to form a toner image on the recording medium.

0004

Conventional wet type recording apparatuses have had the problem that a large amount of developer is consumed for image formation. This is because the toner (generally charged toner particles made of pigment and resin) of the wet developer that forms the toner image on the electrostatic latent image carrier is transferred to the recording medium by electrophoresis. between the image carrier and the recording medium,
This is because it was necessary to fill it with carrier liquid. Since this carrier liquid does not contribute to the final image formation on the recording medium, it has been necessary to evaporate it or collect it and dispose of it.

[0005] Furthermore, in order to prevent image deterioration during the transfer process to a recording medium, a method of dispersing coarse particles is also known (Japanese Patent Laid-Open No. 59967/1983). This method has a problem in that since particles with large diameters adhere to the electrostatic latent image, it is impossible to visualize the image faithfully, resulting in a decrease in resolution.

Furthermore, since the electrostatic transfer process is carried out, the developer must maintain appropriate transfer characteristics (charge amount, viscosity, etc.) during this process, which poses the problem of difficulty in preparing the developer. Ta.

An object of the present invention is to solve the above-mentioned problems, reduce the amount of developer required for development, and realize a wet type recording apparatus that can perform development with a small amount of developer.

Another object of the present invention is to realize an apparatus capable of forming high-quality toner images with a simple configuration.

[0009]

[Means for Solving the Problems] The wet type recording apparatus of the present invention includes: an electrostatic latent image carrier that carries an electrostatic latent image; a pressure means that presses a recording medium against the electrostatic latent image carrier; The present invention is characterized by comprising a developer supply means for supplying a wet developer to a pressing portion between the electrostatic latent image carrier and the recording medium.

0010

[Operation] Since the wet type recording apparatus of the present invention has the above structure, the wet type developer supplied by the developer supply means is interposed between the recording medium and the electrostatic latent image carrier, and is pressed by the pressure means. In this state, the recording medium passes through a pressing section between the recording medium and the electrostatic latent image carrier, and in the process, an image corresponding to the electrostatic latent image is formed on the recording medium.

As described above, in the wet type recording apparatus of the present invention, a toner image corresponding to the electrostatic latent image on the electrostatic latent image bearing member is directly formed on the recording medium, so that less developer is required.
High-quality toner image formation becomes possible. Furthermore, since no transfer process is required, the mechanism can be simplified.

0012

[Example] An example of the present invention will be explained.

FIG. 1 is a cross-sectional view of a printer which is a first embodiment of the wet type recording apparatus of the present invention.

A charging device 4, an exposure device 7, a coating head 12 as a wet developer supply means, a pressure roller 17 as a pressure means, and a cleaning pad 20 are arranged around the photoreceptor drum 1, which is an electrostatic latent image carrier. are arranged sequentially. Furthermore, a suction head 13 is provided to collect excess developer.

The photosensitive drum 1 includes an aluminum tube 2 and an amorphous selenium photosensitive layer 3 deposited around it. It is configured to rotate in the direction of arrow A.

A wet type developer (hereinafter also referred to as developer) is supplied to the coating head 12 in a configuration as shown in FIG. That is, the developer 9 is sent and supplied to the application head 12 from the developer container 8 by the supply pump 10 in the direction of arrow G.

As shown in FIG. 3, the coating head 12 is constructed by laminating and bonding a metal plate 101 and a piezoelectric ceramic plate 102 with a gap (developing slit 105) provided therebetween. Electrodes 104 are provided on both sides of the piezoelectric ceramic plate 102. In the developing slit 105,
The supplied wet type developer 54 is held by capillary force.

The operation of the coating head 12 will be explained. Electrode 1
When a high frequency voltage 103 is applied between 04 and 04, the piezoelectric ceramic plate 102 expands and contracts in the direction of arrow E. In this example,
The piezoelectric ceramic plate 102 is made of PZT with a plate thickness of 1 mm.
Wet developer 5 is placed in the 20 μm development slit 105 using
4 is supplied, the photosensitive drum 1 is driven at 1.8 MHz, and is vibrated in the direction of arrow E to fly the wet developer 54 as minute droplets, thereby forming a developer layer (54) on the photoreceptor drum 1.

The wet developer 54 is made by dispersing toner particles made of pigment and acrylic resin together with a charge control agent and a dispersion stabilizer in a high-resistance petroleum solvent (for example, Isopar, manufactured by Esso) as a dispersion medium. It is configured. Such a developer is shown in, for example, US Pat. No. 3,900,612. The apparatus of this embodiment uses positively charged toner particles.

The charging device 4 has a conductive elastic layer 6 made of conductive urethane rubber on a metal tube 5 kept at a high potential by a power source 23. It comes into contact with the photoreceptor drum 1 under pressure and rotates in the direction of arrow C at the same speed as the photoreceptor drum 1.

Next, the operation will be explained.

First, the image forming process will be explained using FIGS. 1 and 2. A charging device 4 charges the photosensitive drum 1 to a positive potential. In the exposure process, the photoreceptor drum 1 is selectively exposed to light by an exposure device 7 consisting of a laser beam scanner to neutralize the electric charge in the exposed portion. As a result, the photosensitive drum 1 has a positive surface potential (in this embodiment, +
500V), and after the exposure process, the exposure section 56 enters the pressing section 57 with approximately ground potential (for example, +40V).

The recording medium 14 discharged from a paper feeding device (not shown) is conveyed to the pressing section 57, comes into contact with the photosensitive drum 1, and is pressed by the pressing roller 17.

The recording medium 14 includes a base material 15 and a conductive layer 16 laminated thereon.

The developer 54 is held and accumulated on the upstream side of the pressing portion 57. The conductive layer 16 of the recording medium 14 is connected to a power source 22
Therefore, the positive potential is maintained at a value lower than the positive potential of the non-exposed area (+50 V in this embodiment). That is, the conductive roller 21 kept at a constant potential by the power source 22 contacts the conductive layer 16 and applies a predetermined potential. Since the toner particles of the wet developer 54 in the pressing section 57 have a positive charge, when they pass through the pressing section 57 with the photoreceptor drum 1, depending on the electrostatic force,
A force is applied toward the photosensitive drum 1 in the exposed portion, and a force is applied toward the recording medium 14 in the non-exposed portion. As a result,
A developer layer 52 is attached to the non-exposed area. On the other hand, the exposure section 5
In No. 1, an electrostatic force acts to cause the developer to adhere to the photoreceptor drum 1, but due to the above potential relationship, the attraction force between the photoreceptor drum 1 and the developer is not large, so the pressing part does not press. It is peeled off and removed by the squeezing effect of pressure. Further, the carrier liquid is also subjected to a throttling action, and movement of the pressing portion 57 downstream is prevented. Therefore, the developer 54 stays on the upstream side of the pressing portion 57. The amount of developer that remains (including the carrier liquid) increases with time, but when it reaches a certain amount or more, it is sucked by the suction head 13 and the developer container 8
will be collected.

FIG. 4 shows the structure of the suction head 13. It is constructed by laminating plate materials 151 and 152 with a slit 154 in between. The slit 154 communicates with the ventilation section 153. The ventilation portion 153 is sucked by the suction pump 11 and the developer in the slit 154 is collected into the developer container 8 .

As a result, a toner image is formed on the recording medium 14 in accordance with the electrostatic latent image on the photosensitive drum 1.

The recording medium 14 carries a toner image and is stored in a paper discharge tray (not shown). The surface of the photosensitive drum 1 is cleaned of contamination using a cleaning pad 20 made of felt, a release agent is applied thereto, and the drum 1 enters the charging process again.

The surface of the pressure roller 17 is cleaned by the blade 24.

In our experiments, we used a wet developer with a solid content concentration (defined below) of 10 to 30%, and
When the developer layer 54 uniformly coated to a thickness of 00 μm was passed through the pressing part 57 with the photoreceptor drum 1,
A toner image consisting of a wet developer layer 52 of about 5 μm was formed on the recording medium 14. No carrier liquid remained in the non-image area 53. Therefore, there is no need for a squeeze mechanism or the like as used in conventional wet recording apparatuses, and a toner image without background fog can be obtained.

Solid concentration = ((wet developer weight) - (carrier liquid weight)) / (carrier liquid weight) The wet developer 9 in the developer container 8 is supplied by the pump 10 and is supplied to the coating head 12 . Ru. A fixed amount of developer is continuously supplied during the printing operation.

A second embodiment is shown in FIG. This embodiment differs from the previous embodiments in that the pressure roller 17 has a conductive elastic layer 25, which is supplied with a constant potential by a power source 26. In this case, an electric field that visualizes the electrostatic latent image is generated between the pressure roller 17 and the photosensitive drum 1. Therefore, toner image formation can be performed on a recording medium that does not have a conductive layer.

As explained above, in the wet type recording apparatus shown in this embodiment, a toner image is directly formed on the recording medium. Therefore, the electrostatic transfer process required in conventional devices is no longer necessary, and a toner image is formed without containing much carrier liquid, making it possible to reduce the amount of developer. Furthermore, since there is no deterioration in image quality due to transfer, a high quality image can be obtained.

Furthermore, the toner image on the recording medium 14 does not contain much carrier liquid. Therefore, there is no need to evaporate the carrier liquid by heating. Therefore, there is no need to provide a heat fixing device or the like, and there is an effect that power consumption can be reduced.

Although the embodiment of the present invention has been described as an example of a printer equipped with an exposure device using a laser scanner, the same principle can also be applied to a copying device that performs image exposure using reflected light from a document. It is possible.

In order to prevent toner from adhering to non-exposed areas due to absorption of the developer, the recording medium may be a film recording medium or a film-like recording medium whose surface is coated with a non-absorbing layer if the material does not have developer adsorption properties. Paper-like recording media may be used, transparent recording media,
Imaging is also possible on opaque recording media.

[0037]

According to the present invention, the wet developer is supplied from the developer supply means to the pressing portion between the electrostatic latent image carrier and the recording medium. Further, at the pressing portion between the electrostatic latent image carrier and the recording medium, a large electric field acts depending on the electrostatic latent image when the electrostatic latent image carrier passes through a minute gap between the two. Therefore, development is possible even with a developer having a high solid content concentration and low mobility. Therefore, there is no need to maintain the developer at a low viscosity, as in the prior art, when charged toner particles move electrophoretically in a carrier liquid and adhere to an electrostatic latent image carrier. Further, as described above, in an apparatus that undergoes an electrostatic transfer process, the toner image is accompanied by a predetermined amount of carrier liquid on the electrostatic latent image carrier in order to retain the charged charge. In contrast, in the configuration of the present invention, the toner image on the recording medium can be attached in a drier state. Therefore, it is possible to reduce the amount of developer required for image formation and to realize a wet type recording apparatus that can perform development with a small amount of developer. Similarly, since it adheres to the recording medium in a drier state, it also has the effect of shortening the time required for drying.

Furthermore, since the carrier liquid does not adhere to non-image areas on the recording medium, there is no need for a squeeze mechanism as in conventional wet type recording apparatuses. In addition, in conventional devices, the magnitude of the developing electric field that is generated changes depending on the value of the gap between the developing electrodes provided facing the electrostatic latent image carrier, so it is necessary to control this gap dimension with precision. was there. In the apparatus of the present invention, since the electrostatic latent image carrier and the recording medium come into contact with each other under pressure, there is no need to control the size of the minute gap between them. For these reasons, there is also the effect that the device can be mechanically simplified.

Furthermore, in conventional wet-type recording apparatuses, when a toner image on a photosensitive drum is transferred to a recording medium, the image quality of the toner image deteriorates, and it is difficult to transfer the toner image to anything other than a smooth recording medium. In the wet type recording apparatus of the present invention, since a toner image is directly formed on a recording medium, it is possible to form a good image quality.

Furthermore, since the toner image is directly formed on the recording medium as described above, there is no need for an electrostatic transfer process, and the mechanism can be simplified.

Furthermore, in the conventional apparatus, the toner image on the electrostatic latent image carrier that has undergone the development process needs to maintain predetermined electrostatic characteristics in preparation for the transfer process. However, in the configuration of the present invention, since an electrostatic transfer step is not performed, the toner does not need to maintain electrostatic properties. Further, as explained above, development using a high viscosity developer is possible. For these reasons, there is a large degree of freedom in selecting the composition constituting the wet developer, and the wet developer also has the advantage of being easy to prepare.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a wet recording device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the developing operation of the wet recording apparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a coating head that constitutes a wet recording apparatus according to a first embodiment of the present invention.

FIG. 4 is a perspective view showing the configuration of a suction head used in the wet recording apparatus according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view of a wet recording device according to a second embodiment of the present invention.

[Explanation of symbols]

1 Photosensitive drum (electrostatic latent image carrier) 9, 54 Thermal fixing device 12 Application head 13 Suction head 14 Recording medium 17 Pressure roller

Claims (1)

[Claims] [Claim 1] An electrostatic latent image carrier carrying an electrostatic latent image;
It is characterized by comprising a pressure means for pressing a recording medium against the electrostatic latent image carrier, and a developer supply means for supplying a wet developer to a pressing portion between the electrostatic latent image carrier and the recording medium. Wet recording device.