JPH0422681A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To enhance the utilization effect of an ink sheet by entirely exposing powder ink to a wavelength of a photosensitive region before successively supplying the same to an ink sheet in a bias voltage applied state. CONSTITUTION:Powder ink 7 composed of the components almost same to those of a photoconductive ink layer is stored in a two-component developing device 9 and thinly bonded to a conductive sleeve 10 rotating in the direction shown by an arrow 11 by electrostatic force. The transparent conductive layer 4 on the rear of an ink sheet 1 is earthed and bias voltage is applied to the conductive sleeve 10. Photoconductive toner holds insulating properties at the time of non-irradiation but, when the toner is entirely exposed to light of a photosensitive wavelength region before supplied to the ink sheet 1, the charge of the toner is neutralized and the toner is made conductive. The powder ink 7 coming into contact with a non-transfer part 6 becomes a mere charge passing route because the non-transfer part 6 having the same composition as the ink layer 2 absorbs the exposure light to become conductive and is fed on the conductive sleeve 10 by electrostatic force and only the transfer part of the photoconductive ink layer can be replenished with the powder ink 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus used in copying machines, printers, facsimile machines, and the like. More specifically, the present invention relates to a thermal transfer type image forming apparatus having an ink sheet recycling means.

[Prior Art] As an image forming apparatus that forms images using a thermal transfer method, a compact and highly reliable image forming apparatus that is equipped with various types of recording methods such as a melt transfer recording method and a sublimation dye transfer recording method has been proposed. It has been put into practical use.

Furthermore, in order to improve economic efficiency, studies have been made on methods for improving the effectiveness of ink sheet use, methods for dealing with rough paper, and the like.

As a method for improving the effectiveness of ink sheet use, a patent application was filed in 1986.
No. 3-38114 proposes an ink sheet recycling method and apparatus. Images created using the ink sheet produced and recycled using the ink sheet recycling method and apparatus disclosed in Japanese Patent Application No. 63-36114 have a high recording temperature (hereinafter referred to as OD value) and are of high quality. In addition, the repeatability was also good.

[Problem to be solved by the invention] However, although the conventional ink sheet recycling method and device were highly effective for use as a compact, low-priced, and low-running-cost page printer, it is not possible to use a color printer based on the following rationale. It was difficult to do so, and there was a desire for a page printer that could handle only one color.

1. The conductive function of the recycled powder ink depends mainly on black carbon black, and depending on the development method, magnetic powder must be included.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus that improves the effectiveness of using an ink sheet. Another object of the present invention is to provide an image forming apparatus using a regenerative thermal transfer method that can easily support colorization. Still another object is to provide an image forming apparatus that can print clearly even when used many times.

[Means for Solving the Problems] An image forming apparatus of the present invention includes a step of forming an image using a thermal transfer method and a step of recycling an ink sheet using powder ink. A step of exposing the entire surface of the powder ink at least before optical writing during development, a step of developing the powder ink and replenishing the ink while irradiating light during development, and a step of replenishing the ink by using a photoconductive toner as a photoconductive toner. It is characterized by including a step of leveling the ink sheet into a sheet and recycling the ink sheet.

[Function] According to the above structure of the present invention, the powder ink is exposed on the entire surface with a wavelength in the photosensitivity range, and then it is sequentially supplied onto the ink sheet with a bias voltage applied, so that when supplied, the toner becomes conductive. It has become.

Therefore, (1) When the ink layer of the ink sheet is transferred and peeled off during printing, and the photoconductive toner comes into contact with the area where the underlying insulating layer is exposed, it is further irradiated with light in the photosensitivity range. The charge injected according to the product of the capacitance of the insulating layer and the developing bias is deposited onto the insulating layer by electrostatic force.

(2) The powder ink that has come into contact with the unprinted area of the photoconductive ink layer of the ink sheet is made conductive by exposing the ink layer in the unprinted area during development, so that the ink layer penetrates into the powder ink. When passing, the powder ink only serves as a path for the charges and the charges are injected into the ink layer, so the powder ink does not adhere to the surface of the ink layer.

In other words, it is possible to replenish powder ink only in areas where the photoconductive ink layer has been transferred and peeled off by printing and the insulating layer is exposed, and the amount of replenishment also depends on the bias voltage. Powder ink - less than one layer adheres.

In this way, the amount of replenishment of the powder ink can be easily controlled, so if the particle size of the powder ink is controlled, the thickness of the ink layer after fixation will be the same as the initial thickness.

[Example] The structure of the photoconductive powder ink (hereinafter referred to as photoner) used in the image forming apparatus of the present invention is shown below. Basically, a photoconductive material, a sensitizer, a binding and fixing resin, and a coloring agent are used. The toner has a microcapsule structure, with the inner core serving as a fixing/coloring layer and the outer shell serving as a photoconductive layer.

A photoconductive material refers to a material exhibiting the following properties.

A film in which a binder resin and a dye, pigment, or resin alone are mixed and dispersed and applied to form a film is irradiated with light, exhibiting xerographic characteristics, and bright decay observed. This is the case with photoreceptor materials used in copying machines.

Any dye can be selected as the sensitizer depending on the photoconductive agent and the sensitive wavelength range. For example, triphenylmethane dye, diallylmethane dye, monomethine cyanine, trimethine cyanine, pentamethine cyanine, heptamethine cyanine,
styryl dye, oxonol, merocyanine, complex cyanine, azenium dye, azo dye, anthraquinone dye,
Indigo dyes, vinylene dyes, and azomethine are used.

Examples of these types of dyes include rose bengal, acridine orange, rhodamine B, erythrosin, eosin, fluorescein, brilliant green, crystal violet, and the like.

The following can be used as the coloring agent.

Nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, pont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate,
Lamp black, oil black, azo oil black, rose bengal, crystal violet, rhodamine B.

Known insulating thermoplastic resins can be used as the binding resin, including acrylic resins such as polyacrylate and polymethacrylate and their copolymers, styrene resins such as polystyrene and poly-1-methylstyrene, and their copolymers. Copolymers, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, polyester resins and their copolymers, polycarbonate resins, cellulose resins, and polyarylate resins are used alone or in combination.

The following low melting point compounds are used as the fixing core particles.

Candelilla wax, carnauba wax, rice wax, beeswax, lanolin, montan wax, osichelite, paraffin wax, microcrystalline wax, berotratum, polyethylene wax, Fischer-Tropsch wax, montan wax derivatives, paraffin wax derivatives, hydrogenated castor oil, synthetic wax, etc. Waxes, higher fatty acids such as stearic acid and valmitic acid, polyolefins such as low molecular weight polyethylene, polyethylene oxide, and polypropylene, ethylene and
A single substance or a composite selected from olefin copolymers such as acrylic acid copolymer, ethylene/acrylic acid ester copolymer, and ethylene/vinyl acetate copolymer.

Furthermore, the following can be used as necessary.

1) Surfactants or dispersants such as metal soaps and polyethylene glycol.

2) Charge control agents such as electron-accepting organic complexes, chlorinated polyesters, nitrofnic acids, quaternary ammonium salts, and pyridinium salts.

3) Fillers such as talc.

4) Fluidity improvers such as Si02 and TiO2.

Hereinafter, the present invention will be described in detail based on the drawings, but it goes without saying that the present invention is not limited thereto.

FIG. 1 is a schematic diagram showing an image forming apparatus according to the present invention.

The ink sheet 1 is of a roll-up cartridge type, and has a photoconductive ink layer 2 on an insulating layer 3 and a transparent conductive layer 4 on the back side thereof.

After printing is completed, the ink sheet wound up into the cartridge is conveyed in the direction of arrow 8. On ink sheet 1,
The photoconductive ink layer 2 is transferred and peeled off by printing to form an exposed portion 5 of the insulating layer 3 and an untransferred portion 6 of the photoconductive ink layer 2.

Powder ink 7 consisting of almost the same components as the photoconductive ink layer
is stored in the two-component developer 9 and is deposited in a thin layer by electrostatic force onto the conductive sleeve 10 rotating in the direction of the arrow 11. Transparent conductive layer 4 on the back side of the ink sheet 1
is grounded, and a bias voltage is applied to the conductive sleeve 10. The photoconductive toner conveyed by the conductive sleeve 10 maintains its insulating properties when not irradiated, but before being supplied to the ink sheet, the entire surface is exposed to light in the photosensitive wavelength range, so that the electrical charge is neutralized. and the toner becomes conductive. As the irradiation means, a separate light source may be used as shown in FIG. 1, or an optical system combining mirrors may be formed. Of the powder ink 7 supplied onto the ink sheet 1 by the conductive sleeve 10, the powder ink 7 that has come into contact with the portion 5 where the photoconductive ink layer 2 has been transferred and peeled off and the insulating layer 3 is exposed is , and is further deposited on the surface of 5 by being injected with charge by exposing the entire surface to light from the light source 13. However, the powder ink 7 that has come into contact with the untransferred portion 6 simply becomes a path for charges because the untransferred portion 6, which has the same composition as the ink layer 2, absorbs the exposed light and becomes conductive.
It is transported over the conductive sleeve IO by electrostatic force. In this way, only the transfer portion of the photoconductive ink layer 2 can be replenished with the powder ink 7.

Next, the powder ink 7 is fixed onto the photoconductive ink sheet by means 1 such as a heat roller or a heat pressure roller.
4 (in FIG. 1, a heated roller is employed as the fixing means), the ink layer of the ink sheet is regenerated and wound onto the cartridge.

[Example 1] Since the process of the present invention does not use magnetic powder or carbon black, color printing is applicable. FIG. 2 shows a schematic diagram of a color image forming apparatus. The process of the present invention will be explained below with reference to FIG.

Color printing was performed using a cartridge type ink sheet in which color-coded portions of Y, M, and C are sequentially fed.

As the insulating layer 3 of the ink sheet 1, a polyester film with a thickness of 4 μm, as the transparent conductive layer 4, and as the photoconductive ink layer, a microcapsule type ink obtained by the following method was applied by applying heat and pressure. use.

Here, the insulating support 3 is preferably a film that is heat resistant and easy to form (for example, polyester, polysulfone, polyimide, polyaramid).
The powder ink 7 can be in the form of powder ink, paste ink, molten/dissolved ink, or semi-molten/semi-molten ink, but powder ink is preferable. (Figure 2 is depicted using powdered ink) The composition of each color photoner is as shown below.

Basic composition Core resin: Carnauba wax sphere Colorant Photoconductive agent: Zinc oxide sensitizing dye Outer shell binder resin: Butyral resin The colorant and sensitizer in each color toner are as follows.

Cyan toner colorant: copper phthalocyanine sensitizer: NK1870, phthalic anhydride magenta toner colorant: quinacridone sensitizer: tetrabromophenol blue phthalic anhydride yellow toner colorant: disazo Sensitizer system: rose bengal, phthalic anhydride First, carnauba wax and each coloring agent are mixed and crushed to form particles for the inner core.

Next, prepare the following solution.

Zinc oxide: 75 parts by weight Sensitizing dye: 0.075 parts by weight Ethyl alcohol: 100 parts by weight Butyral resin: 75 parts by weight First, the above materials are mixed except for the resin, and homogenized using ultrasonic waves. was dispersed and adsorbed.

Next, a resin is added to this dispersion liquid and subjected to ultrasonic dispersion in the same manner to prepare a zinc oxide dispersed resin solution. Furthermore, inner core particles are added to this resin solution and subsequently uniformly dispersed using ultrasonic waves. In this way, the raw material solution was prepared to have a solid content of 20%, and a spherical color toner with a particle size of 10 μm was prepared by spray drying. Observation with an electron microscope confirmed that the film was coated with a zinc oxide dispersed film with a thickness of about 1 μm.

Ink regeneration means 15 for each color of the three color toners.
Prepared on 16.17, developed and reproduced using the method shown below. First, in the secondary developer 9, the ink sheet is triboelectrically charged while being mixed, and the zero-order ink sheet divided into thin layers for each color is placed on the conductive sleeve 10 on the developer corresponding to that color.
Photoner is replenished to the area where the ink layer has been transferred by printing, and the ink sheet is regenerated. When replenishing the photo toner and regenerating the cyan ink layer, the entire surface is exposed to blue light to further develop the cyan toner. After that, the ink sheet is leveled by heat and pressure. Thereafter, ink sheets for three colors are recycled in the same manner.

The ink sheet 1 that has been subjected to image formation and ink sheet regeneration in this manner can be used to form images again.

When an image was actually formed through this process, the O
, D value of 1.2 to 1.5 was ensured, and good images were obtained with good reproducibility in 10,000 printing tests. The light amount of the exposure system at this time is 1O~20erg/Cm.
I wrote it in 2. This is because the photo toner is made conductive by the pre-exposure, so that background fog does not occur in the ink layer in the untransferred area.

[Comparative Example] In the process of Example 1, the photo toner was conveyed to the ink sheet without performing the pre-exposure step. At this time, the charge on the phototoner remains retained.

Of the powder ink 7 supplied onto the ink sheet 1 by the conductive sleeve 10, the photoconductive ink layer 2 is transferred and
The powder ink 7 that has come into contact with the peeled off portion 5 of the insulating layer 3 is exposed to light from the light source 13 over the entire surface, making it conductive, and adheres to the surface of the ink 5 by being injected with charge from the sleeve.

On the other hand, the powder ink 7 that has come into contact with the untransferred area 6 has the same composition as the ink layer 2 and absorbs the exposed light and becomes conductive. The potentials may be the same, and in this case, there is a possibility that the photoner, which is a charged particle, will be attracted to both the sleeve and the ink sheet, causing some background fog.When the photoner charge is lOμC/g and the developing bias is 500V, The area ratio of background fog to the developed surface was about 5 to 7%.

[Example 2] The process of the present invention can also be applied to ordinary black and white printing. The composition of the phototoner is shown below.

First, carnauba wax particles having a particle size of about 8 μm are directly dyed in an alcoholic solution of black dye-1 to form particles for the inner core.

Next, prepare the following solution.

Zinc oxide...75 parts by weight Cyanine dye...0.075 parts by weight Ethyl alcohol...100 parts by weight Butyral resin...75 parts by weight The cyanine dye for sensitization had the following structure.

First, the above materials were mixed except for the resin, and uniformly dispersed and adsorbed using ultrasonic waves.

Next, a resin is added to this dispersion liquid and subjected to ultrasonic dispersion in the same manner to prepare a zinc oxide dispersed resin solution. Furthermore, inner core particles are added to this resin solution and subsequently uniformly dispersed using ultrasonic waves. In this manner, the raw material solution was prepared to have a solid content of 20%, and a phototoner whose surface was coated by a spray drying method was prepared. Approximately 1 μm according to electron microscope observation
It was confirmed that the zinc oxide dispersed film was coated with a thickness of .

A printing test was conducted using the above-mentioned phototoner using the process of Example 1. Since a cyanine dye having sensitivity in the near-infrared region was used as a sensitizing dye, an exposure device that transmits light in the near-infrared region was used as a light source.

When an image was actually formed through this process, the O
, D value of 1.2 to 1.5 was ensured, and good images were obtained with good reproducibility in 10,000 printing tests. At this time, the amount of light on the developing surface of the exposure system was approximately 10 erg/cm 2 for writing.

[Example 3] Using the black photoner of Example 2, four-color printing was performed. The apparatus was almost the same as in Example 1, but when a black developing device was newly added, an image was actually formed through a single process, and natural color reproduction became possible.

[Effects of the Invention] As described above, the image forming apparatus according to the present invention has a step of forming an image using a thermal transfer method and a step of recycling an ink sheet using powder ink. Using a photoconductive toner as the ink, a step of exposing the entire surface of the powder ink at least before optical writing during development, a step of developing the powder ink and replenishing the ink while irradiating light during development, and replenishing the ink with the refilled toner. By leveling the ink sheet into a sheet and regenerating the ink sheet, it is possible to use toner that does not use magnetic powder or carbon black, and it is possible to use a regenerated thermal transfer method that eliminates background fog on the ink layer in untransferred areas. A forming device is now available.

If the image forming apparatus according to the present invention is used, an image forming apparatus that can easily support color printing, improve the effectiveness of ink sheet usage, reduce running costs, and be able to print clearly even after repeated use. This has the effect of making it possible to provide

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an image forming apparatus showing another embodiment of the present invention. FIG. 3 is a diagram showing an example of the cross-sectional structure of the photoconductive toner used in the present invention. FIG. 4 is a diagram showing the structure of the black dye used in the photoconductive toner of the present invention. 1...Ink sheet 7...Photoner 9...Two-component developer 10...Conductive sleeve 13...Exposure system 18...Thermal head 19...Backup roller 20...Recording paper 23...Beyond the pre-exposure device Applicant: Seiko Epson Corporation Figure 3 x 3

Claims (1)

[Claims] In a surface image forming apparatus having a step of forming an image by a thermal transfer method and a step of recycling an ink sheet using powder ink, a photoconductive toner is used as the powder ink, and at least before optical writing during development. The method includes a step of exposing the entire surface of the powder ink, a step of developing the powder ink while irradiating light during development and replenishing the ink, and a step of leveling the refilled toner into a sheet and recycling the ink sheet. Features of the image forming device.