JPH054452A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the surface of a photosensitive layer containing a photoreversible substance on an image forming drum, and to take measures against deterioration by repeated writing to obtain a clear image. [Structure] The photosensitive layer 2 containing the photoreversible substance of the image forming drum 1 has a plurality of layered structures 2a and 2c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image using a photoreversible reaction substance, and then transferring and fixing the image on a recording medium.

[0002]

2. Description of the Related Art As an apparatus for forming an image, it is exposed to light,
There is an optical printer method for writing. This method
A chemical latent image that selectively exposes an image carrier having a photosensitive layer formed by thinly coating a photoreversible reaction substance, for example, a photoisomerization substance, causes a photoisomerization reaction, and changes the wettability. To form. Development is then carried out by attaching a developer to the chemical latent image, ending the image forming process. After that, transfer and fixing are performed on the recording medium, the developer is cleaned, and the chemical latent image is erased.

[0003]

However, in the above-mentioned prior art, the probability that the photoisomerizable substance is exposed on the surface during the formation of the photosensitive layer is low, and the distribution of the exposed photoisomerizable substance is not uniform. Therefore, there is a technical problem that a high quality image with high resolution cannot be obtained.

Further, when only one thin photosensitive layer is applied, if the image formation is continuously repeated at a high speed in the image forming process, the sensitivity of the photoreceptor is significantly deteriorated and the abrasion resistance of the photoreceptor is also increased. Is small, it becomes difficult to form a clear image when the formed image is transferred and fixed by contact with the recording medium.

Further, if paper dust or dust remains on the surface of the photosensitive layer on the image holding means, light scattering occurs during the exposure process,
A good quality latent image cannot be formed.

Therefore, the present invention is intended to solve the above problems, and an object thereof is to provide an image forming apparatus capable of stably obtaining a high resolution and high quality image for a long period of time.

[0007]

An image forming apparatus of the present invention comprises an image holding means having a photosensitive layer, an exposing means for selectively exposing the image holding means, and a developer on the image holding means. An image forming apparatus comprising: an application unit for applying, a transfer fixing device for transferring and fixing the developer onto a recording medium, and a cleaning unit for cleaning the developer remaining on the image holding unit. The photosensitive layer has a layered structure composed of a plurality of films.

[0008]

According to the above-mentioned constitution of the present invention, a substance which reversibly photoisomerizes, or a plurality of laminated films containing the photoisomerizable substance and an additive, for example, LB, on the image holding means.
(Langmuir-Blodgett) film is formed. Due to the LB film structure, the photoisomerization substance is uniformly exposed on the surface of the photosensitive layer, and the light is selectively irradiated by the exposure means to efficiently cause the photoisomerization reaction. Using the changes in wettability and adsorption that occur at that time, a developer is attached, and then transferred and fixed on a recording medium or the like.

At a time other than the printing process, the photosensitive layer on the surface of which the sensitivity is deteriorated and the smoothness of the surface is lost is periodically
Alternatively, it is removed if necessary. By doing so,
A new photosensitive layer surface is always exposed so that a good image can be obtained.

[0010]

【Example】

(Embodiment 1) FIG. 1 is a cross-sectional view showing the overall structure when the present invention is applied to a printer. In the figure, reference numeral 1 denotes an image forming drum which constitutes an image holding means, and is composed of a hollow drum 1a, a photosensitive layer 2a, 2c and a peeling layer 3b
B layer 15 (see FIG. 2). The photosensitive layers 2a and 2c constituting the LB layer 15 are polymers of polymethacrylate and its derivatives, which are robust and have excellent abrasion resistance, containing a substance partially containing azobenzene which causes a stable isomerization reaction by light. It was formed on the outer periphery of the drum 1a by being chemically bonded to the main chain or side chain of the support. The LB layer 15 is the photosensitive layer 2
a and 2c and a thin release layer 3b made of a polymer having a not so high adhesive force, for example, polyethylene, and several layers in layers, and the total thickness of 50 to 1 on the image forming drum 1a.
It was formed by coating at 000 μm. In FIG. 1, the photosensitive layers 2a and 2c and the release layer 3b are shown as a single layer. When laminating, the photosensitive layer first layer 2a and the release layer 3
The adhesive force between the second layer b and the second layer 2c of the photosensitive layer is different from that of the release layer 3b.
The surface treatment of the photosensitive layers 2a, 2c and the peeling layer 3b is performed so as to be larger than the adhesive force between them, and when the photosensitive layer first layer 2a and the peeling layer 3b are peeled off in the removal process described later, The layer 2c is laminated so that the layer 2c is always exposed. The thickness of one photosensitive layer is several hundred nm to several hundred μ
In m, the thickness of one release layer may be about the same.

In this embodiment, two photosensitive layers are used.
Although the layer and the peeling layer are one layer, the photosensitive layer may have three or more layers and the peeling layer may have two or more layers. Although the photoisomerizable substance is azobenzene, spiropyran, fulgide or the like may be used instead. Further, as the polymer support, polymethacrylate, polycellulose, polystyrene, polyester, polyurethane or the like may be used. The ink 5 is composed of a solvent having polarity, in which a dye or a pigment and an additive (surfactant or the like) are mixed and dispersed, and the image forming drum 1 is formed by the ink applying unit 4 serving as an applying unit. Applied on top. The ink thickness depends on the number of rollers 4a and the rollers 4a.
And is supplied to the surface of the image forming drum 1. In the figure, 6 is an optical writing system, and as a light source,
A laser (including a semiconductor laser) 6a was used. In order for the photoisomerizable substance contained in the photosensitive layer 2 to efficiently photoisomerize, the optimum wavelength absorbed by the photoisomerizable substance and the wavelength of the optical writing system 6 must be matched. When azobenzene is used as the photoisomerizable substance, it is necessary to irradiate light having a wavelength near 440 nm. For that purpose, a spectral sensitizer (for example, phthalocyanine, rose bengal, etc.) may be contained in the photosensitive layer 2, or a nonlinear optical material 6c for converting a wavelength into light may be used in the optical writing system 6. .. As a non-linear optical material, MNA (2-Methyl-4-Ni)
An organic nonlinear optical material such as troaniline) or an inorganic nonlinear optical material such as KDP (KD ₂ PO ₄ ) is used.

Then, according to the recording information, beam scanning and writing are performed on the surface of the photosensitive layer 2 by the polygon mirror 6b or the like.
In the figure, 9 is a cleaning means, which is composed of a puff-shaped cleaning unit. The cleaning unit 9 is provided on the image forming drum 1 so as to be opposed to and in contact therewith, and cleans the surface of the photosensitive layer 2 by removing ink not transferred onto the recording medium 8 and dust from the transfer portion. At the same time, both the first layer 2a of the photosensitive layer and the release layer 3b are removed and removed. Here, the puff shape is used, but a blade shape may be used. 10 in the figure
Is an extinction system for erasing the chemical latent image of the photosensitive layer 2 formed by the optical writing system 6. The extinction system 10 uses a halogen lamp that faces the photosensitive layer 2a (2c) and is arranged on a line in the axial direction of the image forming drum 1.

Next, the operation of such a printer will be described. When the image forming drum 1 is rotationally driven in the direction of arrow A, the photo-isomerization substance contained in the photosensitive layer 2a is isomerized by the light selectively irradiated to the photosensitive layer 2a by the optical writing system 6 according to the printing information. And a chemical latent image is formed by changing the wettability of the surface of the photosensitive layer 2a.
Writing is complete. Specifically, the photoisomerized substance is photoisomerized in the light-exposed portion, and a reaction from the trans form to the cis form occurs, resulting in an increase in the wettability with a polar substance to obtain a chemical latent image. .. The resolution of the chemical latent image is
Since photoisomerization occurs at the molecular level, high resolution, 20
With a capacity of 00 Line / mm or more. After that, the ink 5 is brought into contact with and attached to visualize the image. After that, in the transfer section, the ink image formed on the image forming drum 1 comes into contact with the recording medium 8 and is transferred and fixed by being applied with pressure and heat by the transfer / fixing roller 7. After that, the recording medium 8 is discharged to a discharge tray (not shown). The cleaning unit 9 cleans the untransferred ink, paper dust, and the like on the image forming drum 1. After that, the extinction optical system 1
The chemical latent image of the photosensitive layer 2a isomerized at 0 is erased. Quenching is restored by applying light with a wavelength longer than 500 nm.

The cleaning unit 9 has the above-mentioned L level at a constant time interval or when necessary when not printing.
The photosensitive layer 2a having the B film structure and the lower peeling layer 3b adjacent to the photosensitive layer 2a
Remove layer by layer. As a result, a new photosensitive layer 2c is exposed. In addition, paper dust, dust, and the like that cannot be removed only by the cleaning process and are mixed in at the time of transfer fixing are also removed by the photosensitive layer 2a during the removal process, so that an image with good print quality can always be obtained. It was

Then, the next printing process is prepared.

In the present invention, it is possible to print a plurality of sheets of the same original. After the cleaning process of the operation, the quenching optical system 10 is not operated, and the developer coating unit 4 is held while holding the chemical latent image formed on the surface of the photosensitive layer 2.
Then, the image can be visualized again and the transfer and fixing can be performed.

(Embodiment 2) In this embodiment, as shown in FIG. 3, the photosensitive layer 2 itself formed on the drum 1a is provided with a plurality of LB films 2 without providing the release layer 3b.
The layered structure is composed of a, 2b and 2c and has a total thickness of 0.5 to 10 mm. The LB film was formed by photopolymerization. A photo-radical reaction that is generated by using a long-chain methacrylic acid alkyl ester as the polymer support of the photosensitive layer 2 and chemically bonding a photoisomerizable substance containing a simple substance of azobenzene to its side chain and exposing it to ultraviolet light. Was used for chain polymerization. Even when a long-chain carboxylic acid vinyl ester, an acrylic acid derivative, or a diene compound was used as the photosensitive layer support, photopolymerization was easily performed. Alternatively, the LB film may be formed by using a spin coating method. Example 1 with the above LB film configuration
As described above, in the removal process, the cleaning unit 9 was brought into contact with and brought into close contact with the photosensitive layer 2 to uniformly peel off the film. Then, in the development, transfer / fixing process, the LB film was peeled and removed evenly after a certain period of time, or when necessary, the surface of the photosensitive layer 2 was uniformly removed. With the above structure, it is not necessary to provide the peeling layer 3, and the LB film structure can avoid nonuniformity of peeling and wear.

(Embodiment 3) In this embodiment, a three-layer film structure is formed on the surface of the image forming drum 1a of Embodiment 1 for each function (see FIG. 4). In the figure, 2 is a photosensitive layer containing a photoisomerizable substance. The photosensitive layer 2 is obtained by chemically bonding a spiropyran simple substance which causes an isomerization reaction upon irradiation with light and a substance partially containing spiropyran to the polymer support main chain or side chain of polyacrylic acid and its derivative. Configured. Further, spiropyran may be dispersed and mixed in the polymer support. In the figure, reference numeral 16 denotes a charge generation layer, which is composed of a layer containing a photochargeable substance that generates a charge when exposed to light of 440 nm. As a substance, for example, a layer in which 1% of picric acid was mixed and dispersed in polyvinylcarbazole was used.
The charge generation layer 16 is made of polyvinylcarbazole in addition to 2
A mixture of 10% methylanthraquinone or 0.05% crystal violet may be used. In the figure, reference numeral 17 denotes a charge transport layer, which is composed of a charge transport material that transports charges generated in the charge generation layer 16 toward the photosensitive layer 2. As the substance, for example, a substance obtained by mixing and dispersing a pyrazoline derivative in polycarbonate was used.
Alternatively, a mixture of polyester and oxadiazole may be used. When optical writing is performed on the image forming drum 1 by the optical writing system 6 with the three-layer film structure as described above, the photoisomerizable substance contained in the photosensitive layer 2 causes an isomerization reaction, and the surface of the photosensitive layer 2 is exposed. As the wettability changes,
The writing light passes through the photosensitive layer 2 and the charge transport layer 17 and is applied to the charge generation layer 16 to generate charges. After that, the charges move in the charge transport layer 17 and reach the photosensitive layer 2. As a result, charges are injected into the spiropyran contained in the photosensitive layer 2, and the isomerization reaction is more likely to occur. Furthermore, when an insulating powder toner is used as the ink 5, an electric charge is induced on the surface of the photosensitive layer 2 and the ink 5 easily adheres to the image forming drum 1 by electrostatic force during development. Furthermore, during transfer,
It is possible to efficiently perform electrostatic transfer.

With the above-mentioned structure, even the optical writing system 6 with a small output can efficiently perform optical writing. In addition, development and transfer can be efficiently performed.

[0020]

In the image forming apparatus according to the present invention, the surface of the photosensitive film having deteriorated sensitivity and abrasion resistance due to high speed and high reproducibility is periodically (after a lapse of a certain time), and if necessary. By removing it regularly, a new photosensitive film surface can always be used, so that the sensitivity of the photosensitive layer is constant, a resolution of 2000 Line / mm or more can be obtained in the developing process, and a clear and good image with less density unevenness can be obtained. I was able to get

Further, it is possible to remove paper dust, dust, and the like that are scattered during transfer and fixing, which cannot be removed only by the cleaning unit, and it is possible to always obtain an image with good print quality.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a printer which is an embodiment to which an image forming apparatus of the present invention is applied.

FIG. 2 is a partially enlarged cross-sectional view showing the structure of a photosensitive layer in the same example.

FIG. 3 is a partially enlarged sectional view showing a layer structure of a second embodiment.

FIG. 4 is a partially enlarged sectional view showing a layer structure of a third embodiment.

[Explanation of symbols]

 1 ... Image forming drum 2 ... Photosensitive layer 3 ... Release layer 4 ... Ink application unit 5 ... Ink 6 ... Optical writing system 7 ... Transfer / fixing roller 8 ... Recording medium 9 ... Cleaning unit 10 ... Extinction optical system

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Kitamura 3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation (72) Inventor Isao Mizuma 3-5 Yamato, Suwa City, Nagano Prefecture Seiko -In Epson Corporation

Claims (1)

Claim: What is claimed is: 1. An image holding means having a photosensitive layer, an exposing means for selectively exposing the image holding means, and a coating means for applying a developer onto the image holding means. In an image forming apparatus having a transfer fixing unit that transfers and fixes the developer onto a recording medium and a cleaning unit that cleans the developer remaining on the image holding unit, a plurality of photosensitive layers of the image holding unit are provided. An image forming apparatus having a layered structure made of the film.