JP2006289691A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can do multicolor recording with low energy by using a simple apparatus constitution. <P>SOLUTION: This image forming apparatus comprises an image carrier 1, and a plurality of monochromatic image forming means 5 and 13 which are arranged along a moving surface of the image carrier 1. The image forming apparatus forms a multicolor image by superposing an image developing agent image 25, transferred from each of the means 5 and 13, on the image carrier 11. The means 5 and 13 comprise: an image developing agent supply means 5 with an image developing agent carrier 7 wherein an image developing agent 4 containing at least a thermosensitive adhesive and a coloring agent is stored, and which supplies the image developing agent 4 to the image carrier 1 by carrying the image developing agent 4; and a viscosity imparting means 13 for selectively imparting viscosity to the image developing agent on the carrier 1, depending on image information. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer provided with a developer supply device (developing device) using a developer containing a heat-sensitive adhesive.

  In general, an electrophotographic copying machine or printer image forming apparatus that is widely known uses a photoconductor, charges the photoconductor, exposes and develops by optical writing, and transfers and fixes the developed image onto a recording paper. Then, an image is formed. Further, as an image forming apparatus that does not use a photoreceptor, an ink jet printer and a stencil printing apparatus are known.

  As another image forming apparatus, for example, in Patent Document 1, a recording paper is stacked on a heat-resistant light-transmitting sheet, and a light beam corresponding to an original image is irradiated from the other surface of the heat-resistant light-transmitting sheet to raise toner. There has been proposed a thermal transfer image forming apparatus that is thermally melted and thermally transferred onto a recording sheet.

  Further, for example, in Patent Document 2, a recording paper is brought into contact with a roller having a toner layer formed on a peripheral surface, and a thermal image corresponding to an original image is given from the back surface of the recording paper by a thermal head, whereby a toner image is applied to the recording paper. There has been proposed a thermal transfer image forming apparatus for thermally transferring the image.

Further, for example, Patent Document 3 discloses a thermal transfer image forming apparatus that gives a thermal image corresponding to an image signal from the back side of an image carrier, temporarily fixes a developer image on the image carrier, and thermally transfers it to a recording sheet. Proposed.
JP-A 64-69357 Japanese Patent Laid-Open No. 7-314746 JP 11-91147 A

  Electrophotographic copying machines and laser printers that use a photoconductor to form an electrostatic latent image have a large number of processes for creating an image, and therefore a recording device (electrophotographic process around the photoconductor and its surroundings). There is a problem that the means) is large and complicated.

  In addition, there are problems that the photosensitive characteristics of the photoreceptor deteriorate or change with time, and ozone generation by a high voltage generator that generates corona discharge used in charging, transferring, and discharging processes.

  Ink jet printers have the problem that the recording speed of image formation is slow, and the stencil printing apparatus has problems in the complexity and resolution required to make the master plate.

  The above-described thermal transfer image forming apparatus that thermally transfers a toner image onto a recording paper has a problem that it requires a light beam or a thermal head having a sufficiently high thermal energy to melt and transfer the toner onto the recording paper.

  On the other hand, as shown in Patent Document 3, a thermal transfer image in which a thermal image corresponding to an image signal is given from the back side of the image carrier and the developer image is temporarily fixed to the image carrier and thermally transferred to a recording sheet. Since the forming apparatus does not have a photoconductor, the problem of deterioration with time associated with the photoconductor does not occur, and the size can be reduced and a recording speed equivalent to that of electrophotography can be achieved.

  On the other hand, however, the image recording method disclosed in Patent Document 3 has a big problem that it is difficult to form a color image by arranging a plurality of developer supplying means in the moving direction of the developer carrying member. is there. The reason is as follows.

(1) Since this is a method of giving a thermal image according to image information from the back side of the developer receiving unit, when the first color developer is present on the film, a thermal image is applied to the second color developer. If it is to be applied, heat must be applied through the first color developer. As a result, at the position where the first color developer and the second color developer are formed, a sufficient amount of heat cannot be applied to the second color developer, and the second color image is uneven. Alternatively, if a sufficient amount of heat is applied to the second color developer, a large amount of energy is required.

(2) When heat is applied through the first color developer, the first color developer temporarily fixed on the film may be dissolved and mixed into the second color developer supply means. As a result, the first color image is lost and color mixing problems occur in the developer supply means for the second and subsequent colors. When applying heat with laser light, this problem can be avoided theoretically by selecting a wavelength that transmits the first color developer and heats the second color developer. It is difficult to select such a material.

  In addition, in the method shown in Patent Document 3, it is necessary to keep the image carrier light transmissive over time and to impart heat resistance, but a developer is also formed on the background. This is difficult in the case of a color image having a large amount of color.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having a simple apparatus configuration and capable of multicolor recording with low energy.

  In order to achieve the above object, the invention described in claim 1 includes an image carrier and a plurality of single-color image forming units arranged along a moving surface of the image carrier. An image forming apparatus for forming a multicolor image by superimposing a transferred developer image on the image carrier, wherein the monochromatic image forming means includes at least a heat-sensitive adhesive and a colorant. A developer storage means for storing the developer, a developer supply means having a developer carrier for supporting the developer and supplying the developer to the image carrier, and the developer carrier on the developer carrier An image forming apparatus having a viscosity imparting unit that selectively imparts a viscosity to a developer according to image information is the main feature.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the viscosity imparting unit is configured to irradiate the developer carried on the developer carrying body with a laser beam so that the viscosity is increased. The irradiation position of the laser beam is upstream of the contact portion between the image carrier and the developer carrier in the moving direction of the developer carrier, The main feature of the image forming apparatus is a downstream side of a position where the developer stored in the developer storage means is supplied to the developer carrier.

  According to a third aspect of the present invention, there is provided an image forming apparatus according to the second aspect, wherein the surface layer of the developer carrying member is configured so as not to substantially absorb the laser beam. Features.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, a visible image supplied from the monochromatic image forming means located upstream in the moving direction of the image carrier. The main feature is an image forming apparatus having a higher adhesive strength as an agent.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the developer supplied from the single-color image forming means located upstream in the moving direction of the image carrier is more concentrated in the developer. An image forming apparatus having a large content of the heat-sensitive adhesive is a main feature.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the developer supplied from the monochromatic image forming means located upstream in the moving direction of the image carrier is more concentrated in the developer. The main feature is an image forming apparatus having a high content of the tackifier.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the fourth aspect, the developer supplied from the monochromatic image forming means located upstream in the moving direction of the image carrier is more concentrated in the developer. The main feature is an image forming apparatus having a low content of the heat-fusible substance.

  The invention according to claim 8 is the image forming apparatus according to claim 4, wherein the surface of the solid plasticizer contained in the developer is protected with an inorganic compound or colloidal particles, and the content of the inorganic compound or colloidal particles is The main feature is an image forming apparatus having less developer as the developer supplied by the monochromatic image forming means on the upstream side with respect to the image carrier.

  A ninth aspect of the present invention is the image forming apparatus according to the fourth aspect, wherein the developer contains a photothermal conversion material, and the content of the photothermal conversion material is upstream of the image carrier. The main feature is an image forming apparatus having as many developers as the monochromatic image forming means.

  A tenth aspect of the present invention is the image forming apparatus according to the fourth aspect, wherein the developer contains a photothermal conversion material, and the wavelength of the laser beam scanning device that scans the developer carrier is The laser beam scanning device of the monochromatic image forming means on the upstream side with respect to the image carrier is characterized mainly by the image forming device having a wavelength with high photothermal conversion efficiency of the photothermal conversion material.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the fourth aspect, the amount of light of the laser beam scanning device that scans the developer carrier is such that the monochromatic image upstream of the image carrier. An image forming apparatus that is larger as the laser beam scanning device of the forming unit is the main feature.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the light irradiation time of the laser beam scanning device that scans the developer carrier is upstream of the image carrier. The main feature of the image forming apparatus is that the laser beam scanning apparatus of the monochromatic image forming means is longer.

  According to the first aspect of the present invention, an image forming apparatus capable of multicolor recording can be realized with a simple apparatus configuration and low energy.

  According to the second aspect of the present invention, the transmission of the laser beam is hindered by the already formed developer image, and the loss of thermal efficiency due to the image carrier causes the color balance to be lost and the high-quality that suppresses the decrease in density. An image can be formed.

  According to the third aspect of the present invention, a high-quality image can be formed in which scumming is prevented.

  The invention according to claim 4 can form a high-quality image in which reverse transfer of the developer image already formed on the image carrier is suppressed in multicolor recording.

  In the inventions according to claims 5 to 12, it is possible to realize the developing agents having different adhesive forces with a simple technique.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of a recording apparatus (an image carrier and its surrounding units) in the image forming apparatus according to the first embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a film-like endless image carrier. The image carrier 1 is stretched between rollers 2 and 3, and the roller 2 is driven to rotate in the direction of the arrow (counterclockwise) by a driving means such as a motor, whereby the direction of the arrow a. Move to. In the present embodiment, a polycarbonate having a thickness of 0.02 to 0.2 mm is employed as the image carrier 1.

  On the lower surface of the image carrier 1, developer supply devices 5C, 5M, 5Y, and 5K storing cyan, magenta, yellow, and black developer 4C, 4M, 4Y, and 4K, respectively, are disposed. Each developer supply apparatus has the same structure, and this structure will be described in detail with reference to FIG.

  In the following description, unless the color is limited to a specific color, the developer will be denoted by reference numeral 4 when general developer is described. Similarly, when a general developer supply device that is not limited to a specific color is described, this is denoted by reference numeral 5.

  In FIG. 2, the developer supply device 5 includes a case 6 that houses the developer 4, and a developer as a developer carrier that carries the developer 4 and conveys it to a portion facing the image carrier 1. Mainly from the agent carrying roller 7, the supply roller 8 for supplying the developer 4 in the case 6 to the developer carrying roller 7, and the blade 9 for uniformizing the layer thickness of the developer 4 on the developer carrying roller 7. Configured. Each of the rollers 7 and 8 is driven to rotate in the direction of the arrow (clockwise direction). In the developer supply device 5, a developer removing roller 12 is disposed as a developer removing means in which the tip edge of the cleaning blade 11 is brought into contact with the peripheral surface.

  The developer 4 is pumped onto the developer carrying roller 7 and is regulated by the blade 9, whereby an appropriate amount is guided to the facing portion between the image carrier 1 and the developer carrying roller 7. In this embodiment, electrostatic adhesion is used as a method of pumping the developer 4 onto the developer carrying roller 7.

  That is, the developer carrying roller 7 and the replenishing roller 8 are brought into contact with each other while having a speed difference at the opposite portion, whereby the developer 4 is frictionally charged (negatively charged in this embodiment), and the developer is visualized. The developer 4 is pumped up by applying a voltage having a positive potential to the replenishing roller 8 to the agent carrying roller 7. Note that the method of pumping the developer 4 onto the developer carrying roller 7 is not limited to the method of the present embodiment, and pumping may be performed using non-electrostatic adhesion such as magnetic force.

  As a viscosity imparting means for imparting viscosity to the developer 4 carried on the developer carrying rollers 7 of the developer supply devices 5C, 5M, 5Y, and 5K, a laser beam scanning device 13C shown in FIG. There are 13M, 13Y, and 13K. Since each laser beam scanning device has the same structure, the structure of one laser beam scanning device will be described. In the following, when a general laser beam scanning device that is not limited to a specific color is described, it is denoted by reference numeral 13.

  The laser beam scanning device 13 is mainly composed of a laser light source, a collimator lens (both not shown), a polygon mirror 14, an fθ lens 15, and a strip-shaped reflecting mirror 16 having substantially the same length as the width of the image carrier 1. Then, a thermal image corresponding to the image signal is given to the developer 4 on the developer carrying roller 7 by the laser light L.

  That is, in the present embodiment, the viscosity is selectively imparted to the developer 4 present at the position corresponding to the image portion of the developer 4 carried on the developer carrying roller 7 by the heat of the laser beam. To do. The term “giving viscosity” here refers not only to the case where a material that was originally not viscous is made viscous, but also to the case where the viscosity of a material that was originally viscous is increased to the extent that it adheres to and transfers to the image carrier 1. including.

  In the present embodiment, the developer supply devices 5C, 5M, 5Y, and 5K and the laser beam scanning devices 13C, 13M, 13Y, and 13K constitute a monochromatic image forming unit. That is, four monochromatic image forming units C, M, Y, and K are arranged in parallel.

  A heat roller 17 serving as a heat welding transfer means is disposed on the roller 2 so as to be in contact with and separated from the image carrier 1, and the heat roller 17 is disposed between the roller 2 and the recording material. When 18 is fed by the registration roller pair 19, it comes into pressure contact with the roller 2 through the image carrier 1.

  In the vicinity of the roller 3, a cleaning device 22 in which the cleaning roller 21 is brought into contact with the roller 3 through the image carrier 1 is disposed. A blade 23 is in contact with the cleaning roller 21.

  Next, the developer 4 will be described in detail. The developer 4 includes at least a colorant and a heat-sensitive adhesive. In order to cause heat absorption by laser scanning, the developer 4 contains a photothermal conversion material, or a photothermal conversion layer is provided on the surface layer. As the colorant, carbon black, dyes, and pigments used in general toners can be used.

  The heat-sensitive adhesive has a solid plasticizer or a liquid plasticizer and a thermoplastic resin as essential components, and a tackifier is mixed with these components as necessary. The surface of the adhesive layer of the heat-sensitive adhesive material does not show any adhesiveness at room temperature, but develops adhesiveness due to heating and external load, and maintains the adhesiveness for a while after removing the heat source, First, the solid plasticizer is melted by heating, and the tackiness is developed by melting the thermoplastic resin and the tackifier.

  That is, the expression of adhesiveness is a mechanism that generates an adhesive force by solid-melting a plasticizer so that it is compatible with the thermoplastic resin and plasticizing the thermoplastic resin. The liquid plasticizer is generally encapsulated in microcapsules, and the shell of the microcapsules is broken by heating, and the adhesiveness is developed by melting the thermoplastic resin and the tackifier as described above.

  Hereinafter, although each element of the developer 4 will be described in more detail, the pressure-sensitive adhesive used in the developer 4 of the present invention is not particularly limited to this configuration as long as it is a material configuration that develops viscosity. .

  Various conventionally known resins can be used as the thermoplastic resin used in the heat-sensitive adhesive material of the present invention. Specific examples thereof include, for example, (meth) acrylic acid ester copolymer, styrene-isoprene copolymer, styrene-acrylic acid ester copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene- Resins such as vinyl acetate copolymer, vinyl acetate-acrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-acrylic acid ester copolymer, vinyl acetate-ethylene-styrene copolymer, polybutadiene, polyurethane, etc. Can be mentioned. These copolymers are well known in the art.

  Various conventionally known solid plasticizers can be used as the solid plasticizer used in the heat-sensitive adhesive material of the present invention. Specific examples thereof include hindered phenol compounds, benzotriazole compounds, aromatic sulfonamide compounds, and phthalic acid compounds.

  In the heat-sensitive adhesive material of the present invention, a tackifier can be contained as necessary in order to improve the adhesive force. Specific examples of the tackifier include terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone indene resins, styrene resins, phenol resins, terpene phenol resins, rosin derivative resins, xylene resins, etc. Is mentioned.

  In the heat-sensitive adhesive material of the present invention, a heat-fusible substance can be contained as necessary in order to adjust the adhesive force. Specific examples of the heat-fusible substance include waxes such as animal and plant waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, and acetylated aromatic amines.

  Specific examples include waxes such as paraffin wax, wood wax, carnauba wax, shellac, montan wax, oxidized paraffin, polyethylene wax, oxidized polyethylene, etc., and higher fatty acids such as stearic acid, behenic acid, etc. Examples of aliphatic amides include stearic acid amide, oleic acid amide, N-methyl stearic acid amide, erucic acid amide, methylol behenic acid amide, methylol stearic acid amide, methylene bis stearic acid amide, and ethylene stearic acid amide. Examples of the group anilide include stearic acid anilide and linoleic acid anilide, and examples of the aromatic amine acetylated product include acetoluizide.

  In the heat-sensitive adhesive material of the present invention, an inorganic compound can be contained as necessary in order to adjust the adhesive force. Specific examples thereof include aluminum oxide, magnesium oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, barium hydroxide, calcium carbonate and the like.

  In laser writing, a photothermal conversion material is included to cause the developer 4 to absorb heat at the wavelength of the laser beam and develop adhesiveness. As a material that can provide a photothermal conversion function, generally, as a dye, it has a maximum absorption at 500 to 550 nm, and at 360 to 420 nm, provides a photothermal conversion function with a light transmittance of 10% or more. In general, direct dyes (azo dyes) that exist as dyes, acid dyes (azo dyes, anthraquinone dyes, metal complex azo dyes), basic dyes (azo dyes, triphenylmethane dyes, azine dyes, oxazine dyes, Examples include thiazine dyes, xanthene dyes), vat dyes (anthraquinone dyes), oil-soluble dyes (anthraquinone dyes, azo dyes, metal complex dyes), and disperse dyes (azo dyes, anthraquinone dyes).

  As a material having a maximum absorption at 780 to 850 nm and a light-to-heat conversion function having a light transmittance of 10% or more at 360 to 420 nm, a cyanine compound (polymethine) generally present as a dye can be used. Compounds), phthalocyanine compounds, dithiol metal complex compounds, metal complex compounds, diimmonium compounds, aluminum salt compounds, and the like.

  As the developer 4 using the heat-sensitive adhesive material that can be applied to the image forming apparatus of the present invention, a developer having a heat-sensitive adhesive layer on the surface of the colorant, a thermoplastic resin, a tackifier, and a colorant. It is possible to use particles in which a solid plasticizer is adhered to the surface of the particles mixed with, or particles in which a thermoplastic resin, a tackifier, a solid plasticizer, and a colorant are mixed.

  Next, the operation of the image forming apparatus will be described. First, laser beams corresponding to the image signals of cyan, magenta, yellow, and black are respectively carried by the developer supply devices 5C, 5M, 5Y, and 5K from the laser beam scanning devices 13C, 13M, 13Y, and 13K. The developer 4 on the roller 7 is irradiated. The developer 4 on the developer carrying roller 7 is carried on the developer carrying roller 7 in a state of being regulated to a predetermined layer thickness by the blade 9.

  The thermal energy of the laser beam applied to the developer 4 on the developer carrying roller 7 is such that the laser beam is applied to the extent that the developer 4 adheres to the surface of the image carrier 1 from the developer carrying roller 7. The energy is sufficient to increase the viscosity of the irradiated developer. The developer 4 irradiated with the laser light is heated to become viscous, and is temporarily fixed to the image carrier 1 as a developer image 25 (see FIG. 2).

  Here, the surface layer of the developer carrying roller 7 is made of a material or layer that does not substantially absorb laser light. The reason for this configuration is as follows. Ideally, the developer 4 uniformly exists on the developer carrier roller 7, and as a result, all the laser light is absorbed by the developer 4.

  However, when a region where the developer 4 is not carried on the developer carrier roller 7 is generated due to instantaneous fluctuations, when the region is irradiated with laser light and an exothermic reaction occurs due to photothermal conversion, the image bearing is performed. The developer 4 temporarily fixed on the body 1 is melted by receiving heat from the region, and as a result, the developer 4 temporarily fixed adheres to the developer carrier roller 7 and becomes soiled. Reverse transition may occur. In order to suppress such a phenomenon, it is desirable that the surface layer of the developer carrier roller 7 is configured so as not to substantially absorb laser light.

  Here, “the developer carrier roller 7 does not substantially absorb the laser beam” means that even when the developer carrier roller 7 is directly irradiated with the laser beam, the image carrier 1 has already been temporarily mounted on the image carrier 1. This means that the temperature rise can be suppressed to the extent that the fixed developer 4 does not adhere to the developer carrier roller 7. Therefore, depending on the situation, whether or not it is “substantially absorbed” varies, so it is difficult to clarify this numerically. However, in general, if the light absorption rate is 10% or less relative to the wavelength of the laser beam Thus, the above problems can be suppressed.

  The developer 4 in the non-image area of the image carrier 1 after the temporary fixing step is removed by the electrostatic attraction force of the developer removing roller 12 to which a positive voltage is applied. The developer removing roller 12 is provided to remove the developer 4 other than the developer 4 to be temporarily fixed when it adheres to the non-image portion (so-called “soil stain”). In addition, the suction force of the developer removing roller 12 is determined to be weaker than the temporary fixing force of the developer 4 to the image carrier 1. If the amount of the developer 4 adhering to the non-image portion is sufficiently small, the developer removing roller 12 may not be provided.

  The laser beams from the laser beam scanning devices 13C, 13M, 13Y, and 13K are irradiated on the image carrier 1 at a timing such that cyan, magenta, yellow, and black images reproduce the original color image. On the carrier 1, first, the cyan developer 4C is temporarily fixed from the developer supply apparatus 5C, and then the magenta developer 4M is temporarily fixed from the developer supply apparatus 5M, and then the developer. The yellow developer 4Y is temporarily fixed from the supply device 5Y, and finally the black developer 4K is temporarily fixed from the developer supply device 5K. These layers overlap to form a full-color developer image 25. To do.

  The developer image 25 is transferred and fixed to the recording material 18 by the heat roller 17 at the portion where the image carrier 1 and the heat roller 17 face each other. The recording material 18 is fed from a paper feeding device (not shown), sent to the heat roller 17 in synchronism with the image portion of the image carrier 1 by a pair of registration rollers 19, and is visualized by being heated from the back side. The agent image 25 is transferred and fixed.

  The image carrier 1 after the heat welding transfer process, to which the developer image 25 is transferred and fixed, is cleaned by the cleaning roller 21 to finish a series of recording processes and prepare for the next recording process starting from the developer image temporary fixing process. . Dust containing the developer 4 on the cleaning roller 21 is scraped off by the blade 23.

  In the present embodiment, the developer carrying roller 7 is irradiated with laser light without passing through the image carrier 1. When a color image is formed, the developer temporarily fixed on the image carrier 1 by the upstream developer supply device 5 when the downstream developer supply device 5 irradiates the laser beam. There is a possibility that the image 25 may not be able to perform sufficient heating by blocking the passage of the laser beam.

  If the heating is not performed sufficiently, the density of the color arranged on the downstream side will become unstable or fall, and the color balance will be lost. Therefore, when forming a color image, the laser light is not transmitted through the image carrier 1 in the developer supply devices 5 other than the developer supply device 5C that temporarily fixes the image carrier 1 first. It is preferable to irradiate the paint carrying roller 7.

  In the embodiment, the developer supply device 5C that first temporarily fixes the image carrier 1 is also irradiated with the laser beam on the developer carrier roller 7 without the image carrier 1. However, the developer supply device 5 </ b> C may be configured to be irradiated with laser light through the image carrier 1, that is, from the back side of the image carrier 1.

  In the image forming apparatus of this embodiment, the adhesive force at the time of temporary fixing of the developer 4 supplied to the surface of the image carrier 1 from the developer supply devices 5C, 5M, 5Y, and 5K is applied to the image carrier 1. It is set so that the adhesive force of the developer 4 temporarily fixed first is the strongest and the adhesive force becomes weaker as it goes downstream.

  In other words, the cyan developer 4C has the strongest adhesive strength when temporarily fixed, the magenta developer 4M has the second highest adhesive strength when temporarily fixed, and the yellow developer 4Y has temporarily fixed. Is the third strongest, and the black developer 4K has the weakest adhesive strength when temporarily fixed.

  The reason for this is to suppress the reverse transfer of the developer 4 that has already been temporarily fixed to the image carrier 1 to the developer supply device 5 when the second and subsequent colors are temporarily fixed. For example, when the second color developer 4M to which the adhesive force is applied contacts the image carrier 1, the image carrier 1 or the first color developer 4C temporarily fixed on the image carrier 1 and Simultaneously with the contact, the developer carrying roller 7 or another developer 4M of the second color carried on the developer carrying roller 7 is also brought into contact.

  Hereinafter, the adhesion force between the first color developer 4C temporarily fixed on the image carrier 1 and the second color developer 4M on the developer carrier roller 7 is expressed as F1 (magnitude of force). (Hereinafter, F2, F3, etc. are also the same). The adhesion force between the image carrier 1 and the first color developer 4C temporarily fixed on the image carrier 1 is denoted as F2. Further, the second color developer 4M acting on the second color developer 4M in contact with the first color developer 4C temporarily fixed on the image carrier 1 is drawn toward the image carrier 1 side. The force (the total of other forces such as adhesive force acting between the other second color developer 4M and electrostatic attraction force) is denoted as F3.

  At this time, if F1 is larger than F2 and F3 is larger than F2, the first color developer 4C temporarily fixed on the image carrier 1 is transferred to the developer carrier roller 7 side, and the image is lost. In addition, there is a high possibility of color mixing in the developer supply device 5M for the second color. The second color developer 4M is superimposed on the first color developer 4C without transferring the first color developer 4C temporarily fixed on the image carrier 1 to the developer carrier roller 7 side. In order to transfer to the body 1 side, it is necessary to make F1 and F2 larger than F3.

  On the other hand, when the first color developer 4C is not temporarily fixed on the image carrier 1 and the second color developer 4M is in direct contact with the image carrier 1, the image carrier 1 and the image carrier If the adhesion force between the second color developer 4M contacting the body 1 is denoted as F4, the second color developer 4M cannot be temporarily fixed to the image carrier 1 if F3 is larger than F4. . For stable image formation, F4 needs to be larger than F3.

  Similarly, in the case of the third and subsequent colors, the developer 4Y for the third color to be transferred to the image carrier 1 side is properly transferred, and the developer 4 that has already been temporarily fixed on the image carrier 1 side is revealed. It is necessary to set the relationship of the force that does not transfer to the paint carrying roller 7 side.

  As a result of repeated studies on this point, the present inventor has reached the following conclusion. That is, (1) the adhesive force of the developer 4 to be transferred needs to have a larger adhesive force on the surface on the image carrier 1 side than on the surface on the developer carrier roller 7 side. In the developer 4 to be transferred, by making the adhesive force on the surface on the image carrier 1 side larger than the adhesive force on the surface on the developer carrier roller 7 side, the developer 4 becomes the image carrier. The probability of transferring to the 1 side is improved.

(2) Further, it is desirable that the adhesive force of the developer 4 that adheres first to the image carrier 1 is larger than the adhesive force of the developer 4 that adheres later. Here, “attaching first” and “attaching later” mean the order of attachment to the image carrier 1 when forming the same single multicolor image. In the case of this embodiment, by setting the adhesive strength of the developer 4 in order of increasing cyan, magenta, yellow, and black, the developer 4 that has already been temporarily fixed on the image carrier 1 is located on the downstream side. Reverse transfer to the developer carrying roller 7 can be effectively suppressed.

  Actually, the area where each developer 4 comes into contact with the object varies depending on the distribution state of the developer 4 existing on the image carrier 1 or the developer carrier roller 7. It is difficult to set the working force so as to satisfy the above conditions such as F1, and 100% reverse transition cannot be prevented. However, by paying attention to the above conditions (1) and (2), the stability of image formation can be greatly increased. Specific means satisfying the conditions (1) and (2) will be described later as examples.

  By the way, if the adhesive force of the developer 4 temporarily fixed to the image carrier 1 is set to be the strongest and the adhesive force becomes weaker as going downstream, the developer image 25 on the image carrier 1 is set. It becomes difficult to transfer to the recording material 18. Therefore, in the present embodiment, the heat roller 17 is opposed to the image carrier 1 through the recording material 18, and the adhesive force of the developer 4 that contacts the recording material 18 is increased by heating from the heat roller 17. In this way, by heating the side of the developer 4 on the image carrier 1 in contact with the recording material 18, an image generated when a part of the developer 4 does not transfer to the recording material 18. Omission can be suppressed.

Further, by increasing the pressure applied to the image carrier 1 by the heat roller 17, the interval between the developer 4 is compressed to increase the heat transfer efficiency between the developers 4, and the image omission is effectively suppressed. be able to. In the case of the image forming apparatus of the present embodiment, image omission can be suppressed to a practical level by setting the surface pressure to 1 kg weight / cm ² or more.

  In the present embodiment, a heater is provided in the heat roller 17. However, instead of having a heater in the heat roller 17 or in combination with the heater in the heat roller 17, a developer supply apparatus that performs temporary fixing at the end. A heater may be installed on the downstream side of 5K and upstream of the contact portion between the image carrier 1 and the recording material 18. Even with such a configuration, the adhesive force between the recording material 18 and the developer 4 can be increased, so that image omission can be suppressed.

  FIG. 3 is a configuration diagram of an image forming apparatus according to the second embodiment of the present invention. The same reference numerals are assigned to the same portions as those in the first embodiment.

  In FIG. 3, reference numeral 31 denotes a film-like endless recording material conveying belt. The recording material conveyance belt 31 is driven to rotate by a driving means (not shown) and moves in the direction of arrow a. The recording material conveyance belt 31 of the present embodiment conveys the recording material 18 by electrostatically adhering to the surface thereof. That is, the recording material 18 such as recording paper supplied from the paper feeding device 32 is attracted to the recording material conveyance belt 31 by applying a voltage to the adsorption roller 31a, and moves on the recording material conveyance belt 31, and moves. The developer is supplied from the developer supply devices 5K, 5M, 5C, and 5Y.

  The material of the recording material conveyance belt 31 is the same as that of the image carrier of the first embodiment. Further, since the recording material conveying belt 31 conveys the recording material 18 carrying an image electrostatically attached to the surface thereof, it functions indirectly as an image bearing member.

  The fixing device 33 corresponding to the heat roller 17 in the first embodiment has a heating roller 33a and a pressure roller 33b, and the developer material 25 on the recording material 18 and the recording material 18 (FIG. 1) by these two rollers. 2), the developer image 25 is fixed on the recording material 18 by heating.

  On the side surface of the recording material conveyance belt 31, developer supply devices 5C, 5M, 5Y, and 5K that store cyan, magenta, yellow, and black developer 4, respectively, are disposed. Each developer supply device 5 has the same structure, and this structure will be described in detail with reference to FIG.

  In FIG. 4, the developer supply device 5 includes a case 6 that stores the developer 4, and a developer as a developer carrier that carries the developer 4 to a portion facing the recording material conveyance belt 31. From the developer carrying roller 7, the replenishing roller 8 for supplying the developer 4 in the case 6 to the developer carrying roller 7, and the blade 9 for making the layer thickness of the developer 4 on the developer carrying roller 7 uniform. Mainly composed. Each of the rollers 7 and 8 is driven to rotate in the direction of the arrow (counterclockwise direction).

  The developer 4 is pumped onto the developer carrying roller 7 and is regulated by the blade 9, whereby an appropriate amount is guided to the facing portion between the recording material conveyance belt 31 and the developer carrying roller 7. In this embodiment, electrostatic adhesion is used as a method of pumping the developer 4 onto the developer carrying roller 7.

  That is, the developer carrying roller 7 and the replenishing roller 8 are brought into contact with each other while having a speed difference at the opposite portion, whereby the developer 4 is frictionally charged (negatively charged in this embodiment), and the developer is visualized. The developer 4 is pumped up by applying a positive voltage to the agent carrying roller 7 with respect to the replenishing roller 8. The method of pumping the developer 4 onto the developer carrying roller 7 is not limited to the method of this embodiment, and the pump may be pumped using non-electrostatic adhesion such as magnetic force.

  Laser beam scanning similar to that of the first embodiment is used as a viscosity imparting means for imparting viscosity to the developer 4 carried on the developer carrying rollers 7 of the developer supply devices 5C, 5M, 5Y, and 5K. There are devices 13C, 13M, 13Y, 13K. That is, in the present embodiment, the viscosity is selectively imparted to the developer 4 present at the position corresponding to the image portion of the developer 4 carried on the developer carrying roller 7 by the heat of the laser beam. To do. The term “giving viscosity” as used herein includes not only the case where the originally non-viscous substance is made viscous, but also the case where the viscosity of the originally viscous substance is increased to the extent that it adheres to the recording material. .

  A cleaning device 22 is disposed in the vicinity of the recording material conveyance belt 31. In the cleaning device 22, a blade 23 is in contact with the cleaning roller 21.

  Next, the operation of the image forming apparatus will be described. The recording material 18 such as recording paper supplied from the paper feeding device 30 is attracted to the recording paper transport belt 31 by applying a voltage to the suction roller 31 a and moves on the recording paper transport belt 31, and the developer. It is sent to the facing portion of the supply devices 5C, 5M, 5Y, and 5K.

  The recording material 18 is synchronized with the developer supply devices 5C, 5M, 5Y, and 5K, and the laser beam scanning devices 13C, 13M, 13Y, and 13K are used for cyan, magenta, yellow, and black, respectively. Laser light corresponding to the image signal is irradiated to the developer 4 on the developer carrying roller 7 of each of the developer supply devices 5C, 5M, 5Y, and 5K.

  The developer 4 on the developer carrying roller 7 is carried on the developer carrying roller 7 while being regulated to a predetermined layer thickness by the blade 9. The thermal energy of the laser beam applied to the developer 4 on the developer carrying roller 7 is the surface of the recording material 18 on which the developer 4 is carried from the developer carrying roller 7 onto the recording material conveying belt 31. This energy is sufficient to increase the viscosity of the developer 4 irradiated with the laser beam to such an extent that it adheres to and transfers. The developer 4 irradiated with the laser light is heated to become viscous, and is temporarily fixed as a developer image 25 on the recording material 18.

  The laser beams from the laser beam scanning devices 13C, 13M, 13Y, and 13K are emitted at a timing at which the four color images of cyan, magenta, yellow, and black are superimposed on the recording material 18 so as to reproduce the original color image. The On the recording material 18 carried on the recording paper transport belt 31, the cyan developer 4C is first temporarily fixed from the developer supply device 5C, and then the magenta developer from the developer supply device 5M. 4M is temporarily fixed, then yellow developer 4Y is temporarily fixed from developer supply device 5Y, and finally black developer 4K is temporarily fixed from developer supply device 5K. A full color developer image 25 is formed.

  The developer image 25 formed on the recording material 18 is fixed to the recording material 18 by the fixing device 33 using heat and pressure. The recording material conveyance belt 31 that has finished carrying the recording material 18 is cleaned by the cleaning roller 21 to finish a series of recording processes, and prepares for the next recording process starting from the developer image temporary fixing process. Dust containing the developer 4 on the cleaning roller 21 is scraped off by the blade 23.

Although the developer 4 is not directly adhered to the recording material conveyance belt 31 in the image forming operation, the developer 4 may actually adhere to the recording material conveyance belt 31 during non-image formation. Further, for the purpose of process control, a developer image 25 may be formed on the recording material conveying belt 31 without carrying the recording material 18 to measure the image density. The cleaning device 22 is for removing the developer 4 adhering to the recording material conveyance belt 31 due to such a cause.
Also in the present embodiment, since the developer carrying roller 7 is irradiated with laser light without passing through the recording material conveyance belt 31 as in the first embodiment, it is possible to suppress the color balance from being lost.

  In the image forming apparatus according to the present embodiment, the adhesive force at the time of temporarily fixing the developer 4 supplied to the recording material 18 from the developer supply devices 5C, 5M, 5Y, and 5K is first applied to the recording material 18. The sticking force of the developer 4 temporarily fixed is the strongest, and is set so that the sticking force decreases as going downstream. In other words, the cyan developer 4C has the strongest adhesive strength when temporarily fixed, the magenta developer 4M has the second highest adhesive strength when temporarily fixed, and the yellow developer 4Y has temporarily fixed. Is the third strongest, and the black developer 4K has the weakest adhesive strength when temporarily fixed.

  This is because, as in the first embodiment, the developer 4 that has already been temporarily fixed to the recording material conveyance belt 31 at the time of temporary fixing for the second and subsequent colors is prevented from reversely transferring to the developer supply device 5 side. It is to do. By providing a difference in the adhesive strength at the time of temporary fixing, image omission and color mixing can be effectively suppressed.

  Unlike the first embodiment, in this embodiment, the developer image 25 on the developer carrying roller 7 is directly supplied to the recording material 18. Therefore, unlike the first embodiment, it is not necessary to transfer the developer 4 supplied from the developer carrying roller 7 to another medium again, and therefore the developer 4 temporarily fixed to the recording material 18 first. It is possible to easily set the adhesive strength to be strongest and to become weaker as going downstream.

  The configuration of the developer 4 used in the present embodiment is the same as that of the first embodiment. Further, the same means as in the first embodiment is used as a means for setting the adhesive strength of the developer 4 temporarily fixed to the recording material 18 to be the strongest and to weaken the adhesive strength as going downstream. Can do. In each embodiment, heating with laser light is performed. However, a thermal image may be formed by heating the developer 4 using a thermal head.

  Hereinafter, specific examples of the method for controlling the adhesive strength of the developer 4 will be described. The adhesive force of the developer 4 to be transferred is visualized by the adhesive force on the surface on the image carrier 1 (in the case of the second embodiment, the recording material conveyance belt 31, hereinafter referred to as the image carrier 1). Regarding the method of controlling the adhesive force to be greater than the adhesive force on the surface of the developer carrying roller 7, the distribution of the heat of the developer 4 existing on the developer carrying roller 7 is set so as to become higher toward the outside. That's fine. Specifically, in each embodiment, this is achieved by irradiating a laser beam from the outside of the developer carrying roller 7, but other heating means may be used.

  The following methods are conceivable as a method for controlling the adhesive force of the developer 4 that adheres first to the image carrier 1 to be greater than the adhesive force of the developer 4 that adheres later.

  Example 1 relates to a method of adjusting the adhesion amount or film thickness of a heat-sensitive adhesive material. Specifically, the adhesion amount of the heat-sensitive adhesive material is increased as the developer 4 temporarily fixed first, or the film thickness of the heat-sensitive adhesive material is increased as the developer 4 temporarily fixed first.

  All parts and percentages shown below are on a weight basis. Further, the value indicating the coating amount is the coating amount after drying unless otherwise specified.

  100 parts of a benzotriazole compound as a solid plasticizer, 100 parts by weight of a 10% aqueous solution of polyvinyl alcohol and 200 parts of water as a dispersant are uniformly mixed and pulverized to a mean particle size of 1.0 μm using a ball mill. A plasticizer dispersion [liquid A] was prepared.

  400 parts of the solid plasticizer dispersion [liquid A], 50% solid acrylate emulsion as thermoplastic resin (average particle size 1.1 μm / 90% particle size 1.25 μm, glass transition point 10 ° C., average 100 parts of a molecular weight of 500,000) and 50 parts of a terpenephenol 50% dispersion as a tackifier were mixed to prepare a heat-sensitive adhesive coating liquid [Liquid B].

  Solutions prepared by diluting the thermosensitive adhesive coating solution [B solution] to 90%, 80% and 70%, respectively, BM3 solution, BY3 solution and BK3 solution were prepared. Cyan toner particles were obtained by agglomerating fine particles formed by suspension granulation from a mixed solution of 90 parts of a polyester resin as a binder resin and 10 parts of a cyan organic pigment as a colorant.

  Similarly, a magenta color obtained by agglomerating fine particles formed by suspension granulation from a mixed solution of 90 parts of a polyester resin as a binder resin and 10 parts of a magenta organic pigment / yellow organic pigment / carbon black as a colorant. Toner particles / yellow toner particles / black toner particles were obtained. The heat-sensitive adhesive coating solution [Liquid B] was spray-coated on cyan toner particles and dried to obtain a developer 4C.

  Similarly, heat-sensitive adhesive coating liquid [BM3 liquid] is applied to magenta toner particles, heat-sensitive adhesive coating liquid [BY3 liquid] is applied to yellow toner particles, and heat-sensitive adhesive coating liquid [BK3 liquid] is black. The color toner particles were spray-coated and dried to obtain developer 4M, developer 4Y, and developer 4K.

  By the above method, cyan, magenta, yellow, and black color developers 4C, 4M, 4Y, and 4K having different contents of the heat-sensitive adhesive were obtained.

  Example 2 relates to a method for adjusting the amount of tackifier added. Specifically, the addition amount of the tackifier is increased as the developer 4 temporarily fixed first.

  The heat-sensitive adhesive coating liquid [B] used in Example 1 was mixed with 45%, 40 parts and 35 parts of terpenephenol 50% mixed as a tackifier. An adhesive coating solution [BM4 solution], a heat-sensitive adhesive coating solution [BY4 solution], and a heat-sensitive adhesive coating solution [BK4 solution] were prepared.

  The heat-sensitive adhesive coating solution [Liquid B] was spray-coated on the cyan toner particles used in Example 1 and dried to obtain a developer 4C.

  Similarly, heat-sensitive adhesive coating solution [BM4 solution] is applied to the magenta toner particles used in Example 1, heat-sensitive adhesive coating solution [BY4 solution] is applied to yellow toner particles, and heat-sensitive adhesive is applied. The liquid [BK4 liquid] was spray coated on black toner particles and dried to obtain developer 4M, developer 4Y, and developer 4K.

  By the above method, cyan, magenta, yellow, and black color developers 4C, 4M, 4Y, and 4K having different tackifier contents were obtained.

  Example 3 relates to a method of adding a heat-fusible substance to a heat-sensitive adhesive and adjusting the addition amount. Specifically, the addition amount of the thermoplastic material is reduced as the developer 4 temporarily fixed first.

  400 parts of the solid plasticizer dispersion [Liquid A] used in Example 1 is an acrylic acid ester emulsion having a solid content of 50% as a thermoplastic resin (average particle size 1.1 μm / 90% particle size 1.25 μm, 100 parts of glass transition point 10 ° C., average molecular weight 500,000), 50 parts of 50% terpenephenol dispersion as a tackifier, and 50 parts dispersion of 40% stearamide emulsion, and coated with heat-sensitive adhesive Liquid [C liquid] was prepared.

  Heat sensitive adhesive coating liquid [CM5 liquid], in which the mixing amount of the 40% dispersion of stearamide emulsion mixed in the heat sensitive adhesive coating liquid [C liquid] was changed to 60 parts, 70 parts, and 80 parts, respectively. A heat-sensitive adhesive coating solution [CY5 solution] and a heat-sensitive adhesive coating solution [CK5 solution] were prepared. The heat-sensitive adhesive coating solution [solution C] was spray coated on the cyan toner particles used in Example 1 and dried to obtain a developer 4C.

  Similarly, the heat-sensitive adhesive coating solution [CM5 solution] was applied to the magenta toner particles used in Example 1, the heat-sensitive adhesive coating solution [CY5 solution] was applied to the yellow toner particles, and the heat-sensitive adhesive was applied. The liquid [CK5 liquid] was spray-coated on black toner particles and dried to obtain developer 4M, developer 4Y, and developer 4K, respectively.

  By the above-described method, cyan, magenta, yellow, and black color developers 4C, 4M, 4Y, and 4K having different contents of heat fusible substances were obtained.

  Example 4 relates to a method of adding an inorganic compound to a heat-sensitive adhesive and adjusting the amount of addition. Alternatively, the present invention relates to a method for adjusting the suppression of softening of the solid plasticizer by protecting the surface of the solid plasticizer with an inorganic compound or colloidal particles and adjusting the ratio of the protection. Specifically, the addition amount and the protection ratio are reduced as the developer 4 temporarily fixed first.

  As a solid plasticizer, 100 parts of a benzotriazole compound was heated to melt the surface, and 30 parts of magnesium oxide was applied to the surface. To this compound, 100 parts by weight of a 10% aqueous solution of polyvinyl alcohol as a dispersant and 200 parts of water were uniformly mixed and pulverized to a mean particle size of 1.0 μm using a ball mill to obtain a solid plasticizer dispersion [D liquid]. Was prepared.

  Further, the solid plasticizer dispersion [DM6], the solid plasticizer dispersion [DY6], and the solid plasticizer dispersion [DK6], in which the coating amounts of the above magnesium oxide were changed to 40 parts, 50 parts, and 60 parts, respectively. Made.

  400 parts of the solid plasticizer dispersion [liquid D], acrylic ester emulsion having a solid content of 50% as a thermoplastic resin (average particle size 1.1 μm / 90% particle size 1.25 μm, glass transition point 10 ° C., average 100 parts of a molecular weight of 500,000) and 50 parts of a terpenephenol 50% dispersion as a tackifier were mixed to prepare a heat-sensitive adhesive coating liquid [E liquid].

  Also, the above-mentioned solid plasticizer dispersion liquid [D liquid] was changed to solid plasticizer dispersion liquid [DM6], solid plasticizer dispersion liquid [DY6], and solid plasticizer dispersion liquid [DK6], respectively. Liquid [EM6 liquid], heat-sensitive adhesive coating liquid [EY6 liquid], and heat-sensitive adhesive coating liquid [EK6 liquid] were prepared. A heat-sensitive adhesive coating solution [E solution] was spray-coated on the cyan toner particles used in Example 1 and dried to obtain a developer 4C.

  Similarly, heat-sensitive adhesive coating liquid [EM6 liquid] was applied to the magenta toner particles used in Example 1, heat-sensitive adhesive coating liquid [EY6 liquid] was applied to yellow toner particles, and heat-sensitive adhesive was applied. Liquid [EK6 liquid] was spray-coated on black toner particles and dried to obtain developer 4M, developer 4Y, and developer 4K, respectively.

  By the above method, cyan, magenta, yellow, and black color developers 4C, 4M, 4Y, and 4K having different inorganic compound contents were obtained.

  Example 5 relates to a method for adjusting the addition amount of the photothermal conversion material contained in the heat-sensitive adhesive material. Specifically, the addition amount of the light conversion material is increased as the developer 4 temporarily fixed first.

  0.5% of IR-820B (cyanine compound: manufactured by Nippon Kayaku Co., Ltd.) as a photothermal conversion material is mixed with the heat-sensitive adhesive coating solution [B solution] used in Example 1 with respect to the solid content of B solution. A heat-sensitive adhesive coating solution [F solution] was prepared.

  A heat-sensitive adhesive coating solution in which the amount of IR-820B mixed as a photothermal conversion material in the heat-sensitive adhesive coating solution [F solution] was changed to 0.4%, 0.3%, and 0.2%, respectively. [FM7 solution], heat-sensitive adhesive coating solution [FY7 solution], and heat-sensitive adhesive coating solution [FK7 solution] were prepared. A heat-sensitive adhesive coating solution [F solution] was spray-coated on the cyan toner particles used in Example 1 and dried to obtain a developer 4C.

  Similarly, heat-sensitive adhesive coating liquid [FM7 liquid] is applied to the magenta toner particles used in Example 1, heat-sensitive adhesive coating liquid [FY7 liquid] is applied to yellow toner particles, and heat-sensitive adhesive is applied. The liquid [FK7 liquid] was spray-coated on black toner particles and dried to obtain developer 4M, developer 4Y, and developer 4K, respectively.

  By the above method, cyan, magenta, yellow, and black color developers 4C, 4M, 4Y, and 4K having different tackifier contents were obtained.

  Example 6 relates to a method of adjusting the wavelength of light for laser writing. Specifically, laser writing is performed at a wavelength with higher photothermal conversion efficiency of the photothermal conversion material contained in the developer 4 that is temporarily fixed first.

  The heat-sensitive adhesive coating solution [E liquid] prepared in Example 5 was spray-coated on the cyan toner particles, magenta toner particles, yellow toner particles, and black toner particles used in Example 1 and dried. Thus, cyan, magenta, yellow, and black color developer 4C, 4M, 4Y, and 4K were obtained. The maximum absorption wavelength of the photothermal conversion material contained in the developer 4 is 820 nm.

  The obtained toner of each color was stored in the developer supply devices 5C, 5M, 5Y, and 5K of the image forming apparatus shown in FIG.

  For the laser beam scanning device 13 as an adhesive application means, laser light having an output of 50 mW using an LD light emitting element was used, and writing was performed at a speed of 1000 mm / s. The laser beams of the cyan, magenta, yellow, and black writing devices were selected with wavelengths of 821 nm, 812 nm, 806 nm, and 802 nm, respectively, and writing was performed by attaching them.

  Example 7 relates to a method of adjusting the light quantity for laser writing. Specifically, the light amount of the irradiated laser light is increased as the developer is temporarily fixed first.

  The toner of each color obtained in Example 5 was stored in the developer supply devices 5C, 5M, 5Y, and 5K of the image forming apparatus shown in FIG.

The laser beam scanning device 13 for each color as the tackiness imparting means used laser light having a wavelength of 830 nm using an LD light emitting element, and writing was performed at a speed of 1000 mm / s. Writing was performed by setting laser beam outputs of cyan, magenta, yellow, and black writing devices to 50 mW, 47 mW, 45 mW, and 43 mW, respectively.

  Example 8 relates to a method for adjusting the irradiation time of laser writing light. Specifically, the time for which the laser beam is irradiated is increased for the developer 4 that is temporarily fixed first.

  The toner of each color obtained in Example 5 was stored in the developer supply devices 5C, 5M, 5Y, and 5K of the image forming apparatus shown in FIG.

  For the laser beam scanning device 13 as an adhesion providing means, laser light having a wavelength of 830 nm and an output of 50 mW using an LD light emitting element was used, and writing was performed at a speed of 1000 mm / s. Writing was performed by setting the laser light duty of the cyan, magenta, yellow, and black writing devices to 60%, 57%, 55%, and 53%, respectively.

In addition, the following measures can be taken.
(1) A method of changing the shape of the developer 4 so that the contact area with the image carrier 1 per developer is different. Specifically, the area of contact with the image carrier is increased for the developer 4 that is temporarily fixed first. As this means, it is conceivable that the diameter of the developer 4 temporarily fixed first is increased or flattened.

(2) A method in which a heat-sensitive adhesive material contains a photothermal conversion material having a different absorbance is mentioned. Specifically, the absorbance at the wavelength of the laser beam to be written is increased for the developer 4 that is temporarily fixed first.

1 is a configuration diagram of a recording device (an image carrier and its surrounding units) in an image forming apparatus according to a first embodiment of the present invention. It is a detailed block diagram of the image supply apparatus shown in FIG. It is a block diagram of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a detailed block diagram of the image supply apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 4 Developer 5 Developer supply apparatus (Developer supply means, monochromatic image formation means component)
7 Developer carrying roller (Developing agent carrier)
12 developer removal roller (developer removal means)
13 Laser beam scanning device (viscosity imparting means, monochromatic image forming means constituent elements)
17 Heat roller (thermal welding transfer means)
18 Recording material 25 Developer image 33 Fixing device (thermal welding transfer means)

Claims (12)

An image carrier and a plurality of monochromatic image forming units arranged along a moving surface of the image carrier, and the developer images transferred from the monochromatic image forming units are superimposed on the image carrier. An image forming apparatus that forms a multicolor image by combining them,
The monochromatic image forming means includes:
Developer storage means for storing a developer containing at least a heat-sensitive adhesive and a colorant;
A developer supply means having a developer carrier that carries the developer and supplies the developer to the image carrier;
An image forming apparatus comprising: a viscosity imparting unit that selectively imparts viscosity to the developer on the developer carrying member according to image information. The image forming apparatus according to claim 1.
The viscosity applying means is a laser beam scanning device that applies viscosity to the developer carried on the developer carrying member by irradiating the developer with laser light, and the irradiation position of the laser beam is determined by the laser beam irradiation position. In the moving direction of the image carrier, the developer that is upstream of the contact portion between the image carrier and the developer carrier and stored in the developer storage means is the developer. An image forming apparatus, wherein the image forming apparatus is downstream of a position to be supplied to a carrier. The image forming apparatus according to claim 2.
An image forming apparatus, wherein a surface layer of the developer carrying member is configured not to substantially absorb the laser beam. The image forming apparatus according to any one of claims 1 to 3,
2. An image forming apparatus according to claim 1, wherein the developer supplied from the monochrome image forming means located upstream in the moving direction of the image carrier has a stronger adhesive force. The image forming apparatus according to claim 4.
The image forming apparatus, wherein the developer supplied from the monochromatic image forming unit located upstream in the moving direction of the image carrier has a higher content of the heat-sensitive adhesive in the developer. The image forming apparatus according to claim 4.
The image forming apparatus characterized in that the developer supplied from the monochromatic image forming means located upstream in the moving direction of the image carrier has a higher content of the tackifier in the developer. . The image forming apparatus according to claim 4.
An image characterized in that the developer supplied from the monochromatic image forming means positioned upstream in the moving direction of the image carrier has a lower content of the heat-fusible substance present in the developer. Forming equipment. The image forming apparatus according to claim 4.
The surface of the solid plasticizer contained in the developer is protected with an inorganic compound or colloidal particles, and the content of the inorganic compound or colloidal particles is supplied by the monochromatic image forming means upstream of the image carrier. An image forming apparatus characterized in that the number of developer is less. The image forming apparatus according to claim 4.
A light-to-heat conversion material is contained in the developer, and the amount of the light-to-heat conversion material is larger as the developer supplied by the monochromatic image forming unit on the upstream side with respect to the image carrier. Image forming apparatus.   5. The image forming apparatus according to claim 4, wherein a light-to-heat conversion material is contained in the developer, and the wavelength of the laser beam scanning device that scans the developer carrier is upstream of the image carrier. An image forming apparatus characterized in that the laser beam scanning device of the monochromatic image forming means has a wavelength with high photothermal conversion efficiency of the photothermal conversion material. The image forming apparatus according to claim 4.
2. An image forming apparatus according to claim 1, wherein the amount of light of the laser beam scanning device that scans the developer carrying member is larger as the laser beam scanning device of the monochromatic image forming means upstream of the image bearing member. The image forming apparatus according to claim 4.
The light irradiation time of the laser beam scanning device that scans the developer carrier is longer as the laser beam scanning device of the monochromatic image forming means upstream of the image carrier is longer. apparatus.

Images