JP4356714B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer or a copying machine to which an electrophotographic system or an electrostatic recording system is applied, and more particularly to an image forming apparatus capable of forming a three-dimensional image using a foaming toner.

JP 2000-131875 A

  2. Description of the Related Art Conventionally, image forming apparatuses such as printers and copiers to which the above-described electrophotographic method and electrostatic recording method are applied are designed to planarly print images such as black and white or full-color characters and figures, or photographs on a recording medium such as recording paper. It is generally used for visually recognizing an image formed on the recording medium and transmitting desired information. An image formed on a recording medium such as recording paper is prepared by melting and fixing toner, which is a fine powder made of a synthetic resin containing a color material of a predetermined color, on a recording medium according to image information. In other words, it is formed flat on the recording medium.

  In contrast, a three-dimensional image can convey three-dimensional information to a third party not only from two-dimensional visual information but also from shadows due to height differences and finger tactile sensation. The information that can be transmitted compared to is diversified accordingly, which is very useful. In particular, effective use of a stereoscopic image includes Braille characters, Braille images, and the like. The three-dimensional image is used not only for language information but also for image information such as a map representing terrain, and is indispensable for a visually impaired person.

  In recent years, “barrier-free” has been avoided, and opportunities for visually impaired people to play an active role in society are increasing. By utilizing three-dimensional images in addition to braille characters, visually impaired people can be more active. The place is expected to expand dramatically.

  By the way, as a method of forming this stereoscopic image, the following methods are known. For example, for the production of Braille characters and the like, a method in which protrusions are embossed on a paper surface with a Braille typewriter is widely used. In addition, as a method of duplicating a three-dimensional image and producing a braille book, etc., using a braille image formed on a zinc plate as an original plate according to the same principle as a braille typewriter, There is a method of copying using a Braille printer. In addition, as a method for producing a three-dimensional image pamphlet, etc., ultraviolet curable high-viscosity polymer ink is printed in a mountain shape by using a printing technique such as a normal silk screen, and then irradiated with ultraviolet rays. However, it is not a method that can be easily used in general offices or public facilities.

  Therefore, the applicant of the present invention is a novel image forming toner that can easily form a three-dimensional image using a general copying machine or printer, an image forming apparatus using the image forming toner, and the like. Have already been proposed (Japanese Patent Application No. 10-304458 (Japanese Patent Laid-Open No. 2000-131875)).

  The image forming toner according to Japanese Patent Application No. 10-304458 is configured such that, in an image forming toner containing at least a binder resin and a foaming agent, the foaming agent is not substantially exposed on the toner surface. Is.

  Further, the image forming apparatus using the image forming toner according to Japanese Patent Application No. 10-304458 is a developing means for developing a latent image formed on an electrostatic latent image carrier with toner to form a toner image. And a transfer unit that transfers the toner image to a recording medium, and a fixing unit that fixes the toner image to the recording medium. The toner contains at least a binder resin and a foaming agent, the foaming agent is not substantially exposed on the toner surface, and the fixing unit foams the foaming agent contained in the toner to form a solid. An image is formed on a recording medium.

  However, the conventional technique has the following problems. That is, in the case of the image forming apparatus according to Japanese Patent Application No. 10-304458, the toner contains at least a binder resin and a foaming agent, and the foaming agent is not substantially exposed on the toner surface. And a foaming agent contained in the toner is foamed by a fixing means to form a three-dimensional image on a recording medium, and a toner containing a binder resin and a foaming agent is used. As a result, a stereoscopic image can be formed on the recording medium.

  However, in the case of the image forming apparatus according to the above Japanese Patent Application No. 10-304458, when an image is formed using a toner containing a binder resin and a foaming agent, and this toner image is subjected to a heat fixing process, Since no consideration is given to the technology for controlling the height of the toner image after fixing by changing various parameters, a three-dimensional image is formed on a recording medium such as recording paper, but the toner image after fixing However, there was a problem that the height of the film could not be obtained sufficiently.

  In the case of the image forming apparatus according to the above Japanese Patent Application No. 10-304458, the toner contains at least a binder resin and a foaming agent, and the foaming agent is not substantially exposed on the toner surface. In addition, the three-dimensional image is formed on the recording medium by foaming the foaming agent contained in the toner by the fixing unit. Or the change in the charging potential of the photosensitive drum and the charging characteristics of the toner over time, and the use of toners with different foaming capacities, the height of the final fixed toner image will fluctuate. There is a problem in that a stereoscopic image having a desired height may not be obtained.

  Further, in the case of the image forming apparatus according to the above Japanese Patent Application No. 10-304458, for example, when a Braille image is formed as a three-dimensional image formed by a toner containing a foaming agent, the shape of the Braille 1 dot is as shown in FIG. As shown in FIG. 13, the upper end surface having a diameter of 1 to 1.5 mm is a flat circular image. Therefore, when a braille image is formed based on the technique disclosed in the above Japanese Patent Application No. 10-304458, only an image as shown in FIG. 13 can be obtained, and the image is heat-fixed with foamed toner. There is a problem that the structure of one braille dot cannot be set according to the preference of each individual user.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to easily form a three-dimensional image using an image forming apparatus such as a general copying machine or a printer. It is an object of the present invention to provide an image forming apparatus capable of forming a desired height of a toner image after fixing, as well as being capable of forming a clear image.

  A second object of the present invention is an image that can reliably obtain a three-dimensional image at a desired height even when the environment changes, changes with time, or the foaming ability of the toner used changes. It is to provide a forming apparatus.

  A third object of the present invention is to provide an image forming apparatus capable of forming a stereoscopic image having a desired shape when forming a stereoscopic image such as a Braille image.

In order to solve the above problems, the invention described in claim 1 is formed on the image carrier by the latent image forming means for forming an electrostatic latent image on the image carrier and the latent image forming means. Developing means for developing an electrostatic latent image with toner to form a toner image; transfer means for transferring the toner image onto a recording medium; and fixing means for fixing the toner image transferred to the recording medium. In the image forming apparatus,
When the toner containing at least a binder resin and a foaming agent is used as the toner, and the toner image formed by the toner is fixed on the recording medium by the fixing means, the fixing means is contained in the toner. 1 dot which is the smallest unit constituting one Braille character when forming a three-dimensional image on a recording medium and forming an electrostatic latent image on an image carrier by the latent image forming means By partially changing the latent image potential in one unit image consisting of two images , a three-dimensional shape having a height distribution in which the vicinity of one end rises rapidly and the other is gently inclined is formed. An image forming apparatus is characterized by being made possible.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the one unit image is a one-dot image which is a minimum unit constituting one Braille character.

  In the first aspect of the present invention, when forming the electrostatic latent image on the image carrier by the latent image forming means, the latent image potential in one unit image is partially made different, Since a three-dimensional shape having a desired height distribution can be formed, a three-dimensional image having a desired shape can be formed when a three-dimensional image such as a braille image is formed.

  According to the present invention, it is possible to easily form a three-dimensional image using an image forming apparatus such as a general copying machine or a printer, as well as a desired height of the toner image after fixing. An image forming apparatus capable of obtaining the above can be provided.

  In addition, according to the present invention, there is provided an image forming apparatus capable of reliably obtaining a three-dimensional image having a desired height even when the environment changes, changes with time, or the foaming ability of the toner used changes. Can do.

  Furthermore, according to the present invention, it is possible to provide an image forming apparatus capable of forming a stereoscopic image having a desired shape when forming a stereoscopic image such as a Braille image.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 shows an electrophotographic color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 shows an electrophotographic color copying machine as an image forming apparatus according to Embodiment 1 of the present invention.

  2 and 3, reference numeral 1 denotes a main body of a color printer and a color copying machine. As shown in FIG. 3, an original 2 pressed by a platen cover 3 is placed on the upper portion of the color copying machine main body 1. A document reading device 4 for reading the image is arranged. The document reader 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 from a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. The image reading element 11 composed of a CCD or the like is scanned and exposed through a reduction optical system, and the color material reflected light image of the document 2 is formed at a predetermined dot density (for example, 16 dots / mm) by the image reading element 11. It is supposed to read.

  The color material reflected light image of the document 2 read by the document reading device 4 is subjected to image processing, for example, as document reflectance data of three colors of red (R), green (G), and blue (B) (8 bits each). The image processing apparatus 12 sends a predetermined correction such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame erasing, color / moving editing, etc., to the reflectance data of the document 2. Image processing is performed.

  The image data that has been subjected to the predetermined image processing by the image processing device 12 as described above is a four-color document of yellow (Y), magenta (M), cyan (C), and black (BK) (8 bits each). The color material gradation data is sent to a ROS 13 (RasterOutputScanner). The ROS 13 performs image exposure with laser light according to the original color material gradation data.

  An image forming unit A capable of forming a plurality of toner images having different colors is disposed inside the color electrophotographic copying machine main body 1. The image forming unit A mainly includes an ROS 13 as an image exposure unit, a photosensitive drum 14 as an image carrier on which an electrostatic latent image is formed, and an electrostatic latent image formed on the photosensitive drum 14. And a rotary type developing device 15 as developing means capable of developing a plurality of toner images of different colors.

  2 and 3, the ROS 13 modulates a semiconductor laser (not shown) according to the original reproduction color material gradation data, and emits a laser beam LB from the semiconductor laser according to the gradation data. The laser beam LB emitted from the semiconductor laser is deflected and scanned by a rotary polygon mirror (not shown), and is scanned and exposed on a photosensitive drum 14 as an image carrier through an f · θ lens and a reflection mirror (not shown).

  The photosensitive drum 14 on which the laser beam LB is scanned and exposed by the ROS 13 is rotationally driven at a predetermined speed in the direction of the arrow by a driving unit (not shown). The surface of the photosensitive drum 14 is charged to a predetermined polarity (for example, a negative polarity) and a potential by a scorotron 16 for primary charging in advance, and then a laser beam LB is scanned and exposed in accordance with original reproduction color material gradation data. As a result, an electrostatic latent image is formed. The surface of the photosensitive drum 14 is uniformly charged to, for example, −650 V, and then the image portion is scanned and exposed with the laser beam LB to form an electrostatic latent image in which the exposed portion is −200 V. The electrostatic latent image formed on the photosensitive drum 14 includes four color developing devices 15Y, 15M, 15C, and 15BK of yellow (Y), magenta (M), cyan (C), and black (BK). The rotary developing device 15 reversely develops, for example, with a toner (charged color material) charged to a negative polarity that is the same polarity as the charged polarity of the photosensitive drum 14, so that a toner image T of a predetermined color is obtained. At that time, for example, a developing bias voltage of −500 V is applied to the developing rolls of the developing units 15Y, 15M, 15C, and 15BK. The toner image T formed on the photosensitive drum 14 is negatively charged by the pre-transfer charger 17 as necessary, and the amount of charge is adjusted.

  The toner images of the respective colors formed on the photosensitive drum 14 are transferred onto an intermediate transfer belt 18 as an intermediate transfer member disposed below the photosensitive drum 14 and a primary transfer roll as a first transfer unit. 19, multiple transfer is performed at the first nip portion N1. The intermediate transfer belt 18 is moved at the same moving speed as the peripheral speed of the photosensitive drum 14 by a driving roll 20, a driven roll 21, a tension roll 22 and a backup roll 23 as a counter roll constituting a part of the secondary transfer means. It is supported so as to be rotatable along the arrow direction.

  On the intermediate transfer belt 18, four colors of yellow (Y), magenta (M), cyan (C), and black (BK) are formed on the photosensitive drum 14 according to the color of the image to be formed. All or part of the toner image is transferred in a state of being sequentially superimposed by the primary transfer roll 19. The toner image T transferred onto the intermediate transfer belt 18 is provided with a backup roll 23 that supports the intermediate transfer belt 18 on a recording sheet 24 serving as a recording medium that is conveyed to the secondary transfer position N2 at a predetermined timing. Then, the image is transferred by the pressure contact force and electrostatic attraction force of the secondary transfer roll 25 that constitutes a part of the second transfer means that is in pressure contact with the backup roll 23. As shown in FIGS. 2 and 3, the recording sheet 24 has a predetermined size from a plurality of sheet feeding cassettes 26 serving as recording medium accommodation members disposed in the lower part of the color printer and the copying machine main body 1. Paper is fed by a feed roll 27. The fed recording paper 246 is transported to the secondary transfer position N2 of the intermediate transfer belt 18 by a plurality of transport rolls 28 and registration rolls 29 at a predetermined timing. Then, as described above, a predetermined color toner image is transferred onto the recording sheet 24 from the intermediate transfer belt 18 by the backup roll 23 and the secondary transfer roll 25 as secondary transfer means. It has become so.

  The recording paper 24 onto which the toner image of a predetermined color has been transferred from the intermediate transfer belt 18 is separated from the intermediate transfer belt 18 and then conveyed to the fixing device 30, and the heating roll 31 of the fixing device 30. Then, the toner image is fixed on the recording paper 24 by heat and pressure by the pressure roll 32, and is discharged to the outside of the color printer and the copying machine main body 1 to complete the color image forming process.

  2 and 3, reference numeral 33 denotes a cleaning device for removing residual toner, paper dust, and the like from the surface of the photosensitive drum 14 after the transfer process is completed, and reference numeral 34 denotes a cleaning device for cleaning the intermediate transfer belt 18. The intermediate transfer belt cleaner 35 and a cleaner 35 for cleaning the secondary transfer roll 25 are shown. Further, the intermediate transfer belt cleaner 34 and the cleaner 35 of the secondary transfer roll 25 are configured to contact and separate from the intermediate transfer belt 18 at a predetermined timing.

  By the way, in the first embodiment, in the developing device 15 of the rotary system, four color developing devices 15Y, 15M, 15C, and 15BK of yellow (Y), magenta (M), cyan (C), and black (BK) are used. At least one of them is an image forming toner containing at least a binder resin and a foaming agent, wherein the foaming agent is not substantially exposed on the toner surface.

  The foaming agent is not particularly limited, and any foaming agent can be used as long as it expands by heat. It may be solid at room temperature or liquid. Further, the foaming agent is not limited to a material composed of a single substance, and may be a material composed of a plurality of substances or a functional material such as microcapsule particles. The preferred range of the foaming temperature of the foaming agent varies depending on the apparatus used to form the stereoscopic image, but the stereoscopic image is formed using a normal printer or copying machine as shown in FIGS. In this case, the foaming temperature is preferably not more than the heat fixing temperature.

As the foaming agent, for example, a foaming agent mainly composed of a substance that generates gas by thermal decomposition can be used, and specifically, a bicarbonate such as sodium hydrogen carbonate that generates carbon dioxide by thermal decomposition. And a mixture of NaNO ₂ and NH ₄ Cl that generate nitrogen gas, azo compounds such as azobisirobutyronitrile and diazoaminobenzene, peroxides that generate oxygen, and the like.

  As another form of the foaming agent, a microcapsule particle foaming agent (hereinafter referred to as “microcapsule type”) containing a low boiling point substance that vaporizes at a low temperature (which may be in a liquid state or a solid state at room temperature). May be referred to as a “foaming agent”). A microcapsule type foaming agent is preferable because of its high foaming property. When the image forming toner of the present embodiment is used in an ordinary printer or copying machine, the low boiling point substance contained in the microcapsule can be vaporized at a temperature lower than at least the heat fixing temperature. Specifically, it is a substance that vaporizes at 100 ° C. or lower, preferably 50 ° C. or lower, more preferably 25 ° C. or lower. However, since the thermal responsiveness of the microcapsule type foaming agent depends not only on the boiling point of the low-boiling substance as the core material but also on the softening point of the wall material, the preferred boiling range of the low-boiling substance is not limited to the above range. . Examples of the low boiling point substance include neopentane, neohexane, isopentane, isobutylene, and isobutane. Among them, isobutane which is stable with respect to the wall material of the microcapsule and has a high thermal expansion coefficient is preferable.

  The wall material of the microcapsule has a solvent resistance to various solvents used in the toner manufacturing process, and is impermeable to a gas when a low-boiling substance contained in the microcapsule is vaporized. The material which has is preferable. In addition, when the image forming toner of the present embodiment is used in a normal printer or copying machine, the wall material needs to be softened and expanded at a temperature lower than the heat fixing temperature. Conventionally used wall materials can be widely used as wall materials for microcapsules. For example, homopolymers such as polyvinyl chloride, polyvinyl acetate, polystyrene, polyacrylonitrile, polybutadiene, polyacrylic acid ester, and copolymers thereof are preferably used. Among these, a copolymer of vinylidene chloride and acrylonitrile is preferable in terms of high adhesiveness to the binder resin and high solvent resistance to the solvent.

  The content of the foaming agent in the toner of the present exemplary embodiment varies depending on the type of foaming agent, but is usually 5% to 50% by weight, preferably 10% to 40% by weight. When the content of the foaming agent is less than 5% by weight, the thermal expansion of the toner may be insufficient in practical use. On the other hand, when the content exceeds 50% by weight, the proportion of the binder resin in the toner is relatively high. Insufficient fixing properties may not be obtained.

  The binder resin of the three-dimensional image forming toner of this embodiment is not particularly limited, and resins generally used as toner resins can be used. Specifically, polyester resin, styrene resin, acrylic resin, styrene / acrylic resin, silicone resin, epoxy resin, diene resin, phenol resin, ethylene / vinyl acetate resin, and the like are more preferable. .

  In the binder resin of this embodiment, two or more kinds of the above-mentioned polyester resins may be combined, or another resin may be further combined. Other resins include styrene resin, acrylic resin, styrene / acrylic resin, silicone resin, epoxy resin, diene resin, phenol resin, terpene resin, coumarin resin, amide resin, amideimide resin, butyral resin, urethane resin, ethylene There are natural wax resins such as vinyl acetate resin, polypropylene resin, polyethylene resin and carnauba wax. In the present embodiment, it is preferable to add polyester resin as a main component and other resins in the toner in an amount of 0 to 30% by weight. Further, in the case of preparing a toner by dispersing a foaming agent in a binder resin monomer and subjecting them to suspension polymerization, the suspension-polymerizable monomer in the binder resin can be used.

  FIG. 4 shows an example of a schematic diagram in which the toner particles of the present embodiment are cut and the section is observed with a microscope. As shown in FIG. 4, the toner particles 40 of the present embodiment include at least a binder resin 41 and foaming agent particles 42, and the foaming agent particles 42 are included in the toner core without losing foaming properties. Has been. Since the image forming toner 40 of the present embodiment has a configuration in which the foaming agent 42 is not substantially exposed on the surface, the image forming toner 40 has high thermal expansibility and good adhesion to the recording medium and charging stability. Is maintained.

  Here, “substantially not exposed to the surface” means that, for example, as a result of observing an electron micrograph of 50 toner particles, the foaming agent 42 is completely exposed to the surface as shown in FIG. This indicates that 80% or more of the toner is not used. Further, as shown in FIG. 4, it is preferable that the foaming agent 42 is uniformly dispersed in the toner as particles because the adhesion of the toner to the recording medium and the charging stability can be further improved.

  The image forming toner of the present embodiment may contain a colorant if desired, and may be colored and visualized. As the colorant to be dispersed, known organic or inorganic pigments and dyes and oil-soluble dyes can be used. These colorants depend on the toner particle size and development amount, but generally a ratio of about 1 to 100 parts by weight with respect to 100 parts by weight of toner is appropriate.

  Further, the image forming toner of the present embodiment may contain a magnetic material in order to give magnetization. As the type of the magnetic material, known materials can be used as appropriate. Further, the image forming toner of the present embodiment may contain a release agent as desired. It is preferable to include a release agent since an offset phenomenon at the time of contact fixing can be prevented. It should be noted that a charge control agent may be added to the image forming toner of the present embodiment as desired. Furthermore, a known external additive may be added to the image forming toner of the present embodiment in order to control fluidity and developability.

  In the image forming toner of the present embodiment, for example, an oil phase in which at least a binder resin and a foaming agent are dissolved and / or dispersed in a solvent is suspended and dispersed in an aqueous phase, and particles composed of the oil phase are dispersed. It is produced by a process including a process of producing and a process of removing the solvent from the particles.

  Further, the image forming toner of the present embodiment may be produced by a process including a step of suspension polymerization of a binder resin monomer in which at least a foaming agent is dissolved or dispersed in an aqueous phase.

  The image forming toner used in this embodiment is a white toner containing 75% by weight of binder polymer as a binder resin and 25% by weight of Expandel 461 as a foaming agent, and 74 binder polymer as a binder resin. Black toner containing 1% by weight, 24.7% by weight of EXPANSEL 461 as a foaming agent, and 1.2% by weight of carbon black as a colorant. An external additive may be appropriately added to these image forming toners as necessary.

  When white toner is used as the image forming toner, a dedicated developing device containing the white toner is prepared, and the white developing device is used as yellow (Y) or magenta (M ), Cyan (C), and black (BK), the developing devices 15Y, 15M, 15C, and 15BK may be used. When black toner is used as the image forming toner, the black (BK) developing device 15BK of the rotary developing device 15 may be used as it is. However, as with the white developing device, foam black toner is used. A dedicated developer unit may be used.

  FIG. 5 shows the white toner produced as described above taken with an electron microscope, and FIG. 6 shows the black toner taken with an electron microscope. The volume average particle size of these white toner and black toner was about 30 μm.

  Therefore, in the first embodiment, for example, the above-described foamable black toner is accommodated in the black (BK) developing device 15BK of the rotary developing device 15, and the electrostatic latent image formed on the photosensitive drum 14 is stored. It is comprised so that it may develop. At that time, as shown in FIGS. 2 and 3, the surface of the photosensitive drum 14 is uniformly charged to, for example, −650 V by the primary charging scorotron 16, and then the ROS 13 is used to display characters such as Braille characters. The laser beam LB is scanned and exposed on a desired image portion, and an electrostatic latent image having an exposed portion of −200 V is formed. When forming a three-dimensional image, the electrostatic latent image formed on the photosensitive drum 14 is reversely developed by a black (BK) developing device 15BK containing foaming toner, and a black toner image T is obtained. Become. At that time, for example, a developing bias voltage of −500 V is applied to the developing roll of the developing unit 15BK.

As a result, a toner image having a toner weight of 3 mg / cm ² per unit area is formed on the photosensitive drum 14. The toner image formed on the photosensitive drum 14 is primarily transferred onto the intermediate transfer belt 18 by the primary transfer roll 19, and then the toner image transferred onto the intermediate transfer belt 18 is transferred to the backup roll 23 and the second transfer roll 23. Secondary transfer is performed on the recording paper 24 at the secondary transfer position N2 where the secondary transfer roll 25 is in pressure contact.

  FIG. 7 schematically shows the toner image T secondarily transferred onto the recording paper 24. FIG. 8 is a photograph of the toner image T secondarily transferred onto the recording paper 24 taken with an electron microscope. As shown in FIGS. 7 and 8, for example, a toner image T in which foamable toner particles 40 are laminated in about two layers is transferred onto the recording sheet 24. The height of the unfixed toner image T was 55 to 60 μm.

  Next, the recording paper 24 onto which the toner image composed of the foamable toner particles 40 is transferred is heated and pressurized by a heating roll 31 and a pressure roll 32 of a fixing device 30 as shown in FIGS. Then, the binder resin 41 in the toner 40 is melted and the foaming agent 42 in the toner 40 is foamed to fix the stereoscopic image on the recording paper 24. In the stereoscopic image fixed on the recording paper 24, as shown in FIG. 10, the foaming agent 42 in the toner particles 40 foams to form a hollow gas bubble 43 having a substantially spherical shape or a substantially elliptical shape. The gas bubbles are stacked. Further, the surface of the gas bubble 43 is covered with a binder resin 41 which is melted to form a film.

  By the way, the first embodiment is configured to control the height of the stereoscopic image on the recording medium by changing at least one of the image forming conditions, the image forming material, and the recording medium. . As the image forming condition, for example, a fixing speed in a fixing unit is used.

  FIG. 9 is an electron micrograph obtained by actually photographing a stereoscopic image made of foamed toner fixed on the recording paper 24 as described above. The height of the toner image T after the fixing was 130 μm.

  In FIG. 9, the fixing process is performed under the conditions that the fixing temperature is 150 ° C., the nip width between the heating roll 31 and the pressure roll 32 is 4.8 mm, and the fixing speed is 35 mm / sec.

  As can be seen from FIG. 9, the toner image T is three-dimensionally formed on the recording paper 24 in a highly foamed state. Further, it can be seen that the stereoscopic image 44 is formed in a state in which a plurality of gas bubbles 43 (about 3 to 5 layers) in which the foaming agent 42 in the foamed toner 40 is foamed are laminated.

  FIG. 11 is an electron micrograph obtained by sequentially enlarging the stereoscopic images fixed on the recording paper 24.

  As is apparent from FIG. 11, hollow gas bubbles 43 that are almost uniformly foamed in a substantially spherical or elliptical shape are formed in a state where a plurality of layers (about 3 to 5 layers) are densely stacked. I understand that.

  Further, FIG. 12 is an electron micrograph obtained by enlarging the surface of the stereoscopic image fixed on the recording paper 24 and the interface between the toner and the paper.

  As is clear from FIG. 12A, it can be seen that the hollow gas bubbles 43 foamed in a substantially spherical shape or a substantially elliptical shape are arranged almost uniformly on the surface of the stereoscopic image. 12B, it can be seen that the binder resin 41 of the toner 40 partially penetrates into the fibers of the recording paper 24 at the interface between the toner 40 and the paper 24. As shown in FIG.

  FIG. 13 is an electron micrograph of a three-dimensional image formed and fixed in a dot shape on the recording paper 24, taken obliquely from above and inclined at 10 °. In FIG. 13, the fixing process is performed under the conditions that the fixing temperature is 147 ° C., the nip width between the heating roll 31 and the pressure roll 32 is 4.8 mm, and the fixing speed is 35 mm / sec.

  As can be seen from FIG. 13, in the case of the three-dimensional image 44 using the foamed toner 40, it can be seen that a dot-like image is formed, and various characters such as Braille characters and Braille images are used. It can be seen that it can actually be used for the purpose of.

  For comparison, FIG. 14 is an electron micrograph obtained by photographing a flat image formed and fixed in a dot shape with a normal black toner on the recording paper 24 from an obliquely upward direction inclined by 10 ° and a cross section thereof. . In FIG. 14, the fixing process is performed under the conditions that the fixing temperature is 147 ° C., the nip width between the heating roll 31 and the pressure roll 32 is 4.8 mm, and the fixing speed is 75 mm / sec.

  As can be seen from FIG. 14, in the case of an image using normal toner, it hardly rises from the surface of the recording paper 24, and a flat image is simply formed.

Experimental example 1
Therefore, the present inventors change how the height of the stereoscopic image after fixing changes when the fixing speed (process speed) in the fixing device 30 is changed when forming a stereoscopic image under the above conditions. An experiment was conducted to investigate whether or not.

  FIG. 1 is a graph showing the results of the experiment. 15 to 18 are electron micrographs obtained by photographing the cross section of the stereoscopic image fixed on the recording paper 24 at different magnifications. 15 to 18, the fixing temperature is 150 ° C., the nip width between the heating roll 31 and the pressure roll 32 is 4.8 mm, the fixing speed is 70 mm / sec in FIG. 15, and 35 mm / sec in FIG. No. 17 is 17.5 mm / sec, and FIG. 18 is a fixing process performed at an ultra-low speed of 7 mm / sec. As the recording paper 24, J paper manufactured by Fuji Xerox Office Supply Co., Ltd. was used.

  As is apparent from the graph of FIG. 1, it can be seen that by decreasing the fixing speed (process speed), the height of the toner image increases accordingly. When the change in toner image height at this fixing speed (process speed) is approximated by a straight line, the fixing speed is v (mm / sec) and the height of the foamed toner image after fixing is t (μm). The height t of the subsequent toner image is t> −1.5v + 170. Therefore, by controlling the fixing speed v (mm / sec), it is possible to obtain a desired height t (μm) of the foamed toner image after fixing.

Experimental example 2
Next, the present inventors investigate how the height of the fixed three-dimensional image changes when the fixing temperature in the fixing device 30 is changed when forming the three-dimensional image under the above conditions. The experiment was conducted.

  FIG. 19 is a graph showing the results of the experiment. FIG. 20 is an electron micrograph of a cross-section of a stereoscopic image fixed on the recording paper 24 taken at different fixing temperatures. In FIG. 20, the nip width between the heating roll 31 and the pressure roll 32 is 4.8 mm, the fixing temperature is 130 ° C. in FIG. 20B, 150 ° C. in FIG. 20B, and FIG. The fixing process is performed at 170 ° C. and FIG. As the recording paper 24, J paper manufactured by Fuji Xerox Office Supply Co., Ltd. was used.

  As is apparent from the graph of FIG. 19, it can be seen that the height of the toner image tends to increase as the fixing temperature increases. However, when the fixing temperature is as high as 180 ° C., the height of the toner image tends to decrease. This is because if the fixing temperature is as high as 180 ° C., the foaming agent in the foamable toner foams, but the binder resin in the foamable toner is too soft to maintain the foamed state. Conversely, it is considered that the height of the toner image is lowered.

  Thus, it can be seen that by controlling the fixing temperature, the height of the toner image can be changed accordingly.

Experimental example 3
Furthermore, the present inventors change how the height of the stereo image after fixing changes when the basis weight of the recording paper 24 as a recording medium is changed when forming a stereo image under the above conditions. An experiment was conducted to investigate whether or not.

  FIG. 21 is a graph showing the results of the experiment. FIGS. 22 and 23 are electron microscopes in which cross-sections of stereoscopic images fixed on various recording papers 24 having different basis weights are taken at different magnifications, and the height of the stereoscopic image after fixing is measured. It is a photograph. 22 and 23, the fixing process is performed under the conditions that the fixing temperature is 147 ° C., the nip width between the heating roll 31 and the pressure roll 32 is 4.8 mm, and the fixing speed is 35 mm / sec. .

As apparent from the graph of FIG. 21, the toner image height changes accordingly by changing the basis weight of the recording paper 24. The smaller the basis weight of the recording paper 24, the lower the toner image height. Can be seen to increase accordingly. When the change in toner image height with respect to the basis weight of the recording paper 24 is approximated by a straight line, the basis weight of the recording paper 24 is x (g / m ² ), and the height of the foamed toner image after fixing is t (μm). In this case, the height t of the toner image after fixing is t> −x + 200. Therefore, the desired height t (μm) of the foamed toner image after fixing can be adjusted by changing the basis weight of the recording paper 24 by x (g / m ² ).

Experimental Example 4
In addition, when the present inventors form a three-dimensional image under the above conditions, the height of the three-dimensional image after fixing is changed when the thickness and density of the recording paper 24 as a recording medium are changed. An experiment was conducted to see if it changed.

As a result, when the thickness of the recording paper 24 is t (μm) and the density of the recording paper 24 is ρ (g / cm ² ), the recording paper 24 in a range satisfying t <70 and ρ <5 is used. It has been found that the foamed toner may be heat-fixed.

Experimental Example 5
Furthermore, the present inventors conducted an experiment to determine how high the height of the three-dimensional image after fixing is based on the particle diameter of the foamable toner when forming a three-dimensional image under the above conditions. . The experimental conditions were as follows: the fixing speed was 35 mm / sec, the fixing temperature was 147 ° C., the nip width between the heating roll 31 and the pressure roll 32 was 4.8 mm, and the toner amount was 3 mg / cm ^2. It is. As the recording paper 24, J paper manufactured by Fuji Xerox Office Supply Co., Ltd. was used.

  As a result, by changing the fixing conditions and the like, when the average particle diameter of the foamed toner is d (μm) and the height of the foamed toner image after fixing is t (μm), the height of the toner image after fixing It was found that a good stereoscopic image can be formed in the range of 1.5d <t <15d.

  Here, when the height t of the toner image after fixing is 1.5 d or less, the foamed toner is not sufficiently foamed, and the required height of the three-dimensional image cannot be obtained. When the height t of the subsequent toner image is 15d or more, the foamed toner is too foamed and brittle, and the strength is insufficient.

Embodiment 2
FIG. 24 shows the second embodiment. The same parts as those in the first embodiment will be described with the same reference numerals. In the second embodiment, a stereoscopic image is formed by the image forming apparatus. In this case, when the toner containing at least a binder resin and a foaming agent is used as the toner, and the toner image formed by the toner is fixed on the recording medium by the fixing means, the fixing means The height detecting means includes a height detecting means for foaming a foaming agent contained in the toner to form a three-dimensional image on the recording medium and detecting the height of the three-dimensional image formed on the recording medium. The control unit is configured to control the height of the finally obtained stereoscopic image within a desired range by changing the image forming condition based on the height of the stereoscopic image detected by That.

  That is, in the second embodiment, as shown in FIG. 24, fixing processing is performed by the fixing device 30 on the upper part of the paper conveyance path located on the downstream side of the fixing device 30, and heat fixing on the recording paper 24 is performed. A laser displacement meter 50 is provided as a height detecting means for detecting the height of an image formed in three dimensions by foaming the foamed toner. As this laser displacement meter 50, for example, LT-8000 manufactured by Keyence Corporation is used. Then, the height of the toner image on the recording paper 24 after fixing is detected by the laser displacement meter 50. When the height of the toner image detected by the laser displacement meter 50 deviates from a desired range, development is performed. The height of the toner image is controlled by changing the magnitude of the electric field or the like.

  For example, an output as shown in FIG. 25 is obtained from the laser displacement meter 50. In the output waveform shown in FIG. 25, a line image having a width of 1.5 mm is detected by the laser displacement meter 50, and the height of the line image detected by the laser displacement meter 50 is about 150 μm.

  The relationship between the development electric field and the height of the toner after fixing is as shown in FIG. 26, for example, and a toner image formed on the photosensitive drum 14 by changing the development electric field (development bias). As a result, the height of the toner image fixed on the recording paper 24 can be controlled.

  In order to change the developing electric field, it is necessary to change at least one of the developing bias, the charging potential of the photosensitive drum 14, and the exposure potential of the photosensitive drum 14, but the potential difference between the background portion of the image and the developing bias is different. When it becomes smaller, background fogging where toner adheres to the background portion of the image occurs, so the charging potential of the photosensitive drum may be changed simultaneously with the developing bias.

  FIG. 27 is a block diagram showing a control unit of the image forming apparatus according to this embodiment.

  In FIG. 27, reference numeral 50 denotes a laser displacement meter, and the output of the laser displacement meter 50 is converted into a digital value as a voltage corresponding to the height of the toner image and input to a control circuit 51 including a CPU or the like. This control circuit 51 refers to a table or the like in which the relationship between the height of the toner image and the development bias as shown in FIG. The developing bias applied to the developing device 15 is controlled via the bias controller 52.

  Further, even if the toner density of the developing device 15 is changed, the height of the toner image after fixing can be controlled as shown in FIG. Furthermore, the height of the toner image after fixing can also be controlled by changing the fixing temperature as shown in FIG. 29 or changing the fixing speed as shown in FIG.

  FIG. 31 shows how the height of the fixed image changes in degrees when the fixing temperature and fixing speed are changed. As can be seen from FIG. 31, the height of the fixed image increases as the fixing temperature increases and the fixing speed decreases.

  In the above embodiment, in order to detect the height of the toner image, a vertical or horizontal line image having a width of about 1.5 mm and a length of about 5 mm is written on the end of the recording paper 24. The height of this line image is detected. However, the present invention is not limited thereto, and the height of the toner image is detected by a normal image formed on the recording paper 24, or an image dedicated to height detection is formed on the entire surface or a part of the dedicated paper. Of course, the height of the toner image may be detected by an image dedicated to the height detection.

  In the above embodiment, a non-contact laser displacement meter is used as the height detection means. However, as shown in FIG. 32, a contact-type height detection means can also be used. As shown in FIG. 32, the contact-type height detection means 60 includes a rod-shaped contact member 61 made of metal or plastic that contacts the surface of the toner image after fixing. The contact member 61 is swingably supported around a fulcrum 62, and the rear end side of the fulcrum 62 is stretched by a tension spring 63, and is formed in a substantially semicircular shape. The leading end is configured to contact the surface of the recording paper 24 with a constant pressure. The contact member 61 is provided with detection means 64 for detecting the amount of movement (vertical amount) of the contact member 61 at the base end portion set longer than the distance between the fulcrum 62 and the distal end portion. This detection means 64 optically detects the amount of movement of the contact member 61, and a light shielding plate 65 formed so that the edge is inclined is integrally formed at the base end portion of the contact member 61. Is provided. On both sides of the light shielding plate 65, as shown in FIG. 32, a light emitting element (not shown) and a light receiving element (not shown) provided with a linear light receiving window 66 for receiving light emitted from the light emitting element are shielded. It arrange | positions so that it may oppose through the board 66. FIG.

  Then, as shown in FIG. 32, the contact-type height detection means 60 moves when the tip 61a of the contact member 61 moves by contacting a three-dimensional toner image 67 such as Braille. The movement of the front end 61a is enlarged by the lever principle, the rear end 61b of the contact member 61 is moved, and the light shielding plate 65 provided at the rear end of the contact member 61 is emitted from the light emitting element. The amount of light that is received is different, and the amount of light received by the light receiving element changes. Therefore, by detecting the amount of light received by the light receiving element, the amount of movement of the tip of the contact member 61, that is, the height of a three-dimensional toner image such as Braille can be detected.

  Here, if the shape of the tip of the contact member 61 is set to a length of, for example, about 12 mm or more, which corresponds to the space between the braille lines in the direction perpendicular to the drawing sheet, the detection can be performed without creating a line image for detection. Is possible.

  Further, it may be determined whether or not a Braille image exists in the area of the paper detected by the contact member, and a line image may be formed only when it does not exist.

  As shown in FIG. 33, a metal part 68 that acts as an electrode and a counter electrode 69 that faces the metal part 68 are provided instead of the change in the amount of light due to the light shielding plate, and between the metal part and the counter electrode 69. The capacitance may be detected by the capacitance detection circuit 70 and the amount of movement of the contact member 61 may be detected by utilizing the change in the capacitance of the contact member 61. In this case, for the contact member portion 68 facing the counter electrode 69, it is necessary to use a conductive material such as metal or conductive plastic.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

Embodiment 3
FIG. 34 shows the third embodiment. The same parts as those in the first embodiment will be described with the same reference numerals. In the third embodiment, a stereoscopic image is formed by the image forming apparatus. In this case, when the toner containing at least a binder resin and a foaming agent is used as the toner, and the toner image formed by the toner is fixed on the recording medium by the fixing means, the fixing means When the foaming agent contained in the toner is foamed to form a three-dimensional image on the recording medium, and when the electrostatic latent image is formed on the image carrier by the latent image forming means, the latent image in one unit image is formed. By partially varying the image potential, a three-dimensional shape having a desired height distribution can be formed.

  In the third embodiment, the one unit image is configured to be a one-dot image that is the minimum unit constituting one Braille character.

  That is, in the third embodiment, as shown in FIG. 34, a Braille image processing unit 71 that processes a Braille image is provided inside the image processing apparatus 12, and the Braille image processing unit includes the image forming unit. Character information is input from a personal computer 72 to which the apparatus is connected. The braille image processing unit 71 is configured to convert a character image input from the personal computer 71 into a braille image according to a predetermined braille list.

  FIG. 35 is an electron micrograph showing a cross section of one Braille image when a Braille image is formed using the image forming apparatus.

  FIG. 36 is a graph showing the results of measuring the height and size of one Braille image.

  At that time, in the image forming apparatus, as shown in FIG. 37, when a Braille image is basically expressed by the presence or absence of unevenness of 8 dots, the shape of a 1-dot image that is the minimum unit constituting one Braille character is used. (Referred to as one unit image) from a basic shape having a flat upper end surface as shown in FIG. 38 (a) to a substantially mountain shape with a raised central portion as shown in FIG. 38 (b). As shown in FIG. 38 (c), the vicinity of the left end suddenly rises rapidly, and the right side gently slopes. As shown in FIG. 38 (d), the vicinity of the right end suddenly rises rapidly. A solid shape having a desired height distribution, such as a gently sloping shape on the left side, two generally mountain-shaped shapes that rise high on the left and right sides as shown in FIG. The shape can be formed and the user can pre- When instructing the door, so that it is possible to select the shape of one dot of the image which is the minimum unit constituting the braille character. At that time, the size of the braille image may be arbitrarily selected.

  By the way, as described above, various image shapes of one dot, which is the minimum unit constituting one Braille character, expose a Braille image on the photosensitive drum 14 as shown in FIGS. At that time, the exposure distribution within one Braille dot is changed to form an image potential profile on the surface of the photosensitive drum 14 in a predetermined shape, and development, transfer, and fixing are performed using foamed toner according to the image potential profile. Formed by.

  The ROS 13 as a latent image forming unit that performs image exposure on the photosensitive drum 14 to form an electrostatic latent image turns on a semiconductor laser in accordance with an image signal, and applies laser light to the surface of the photosensitive drum 14 in a predetermined manner. The desired electrostatic latent image is formed by irradiating with a resolution of 600 dpi (for example, 600 dpi).

  At this time, when the resolution of the laser light written by the ROS 13 is, for example, 600 dpi, one dot exposed by the laser light has a circular shape with a diameter of about 42 μm. Therefore, when exposing one dot of Braille having a diameter of about 1.4 to 1.5 mm, by controlling the exposure amount continuously (for example, in 256 steps) for each constituent dot of the resolution of ROS13, Image exposure as shown in FIGS. 38A to 38E is possible.

  39 to 41 show the results of experimental examples conducted by the present inventors. Image exposure as shown in FIGS. 38 (a), 38 (b) and 38 (e) was performed. 2 is an electron micrograph showing a cross-sectional shape of a toner image on a recording sheet on which an electrostatic latent image is formed and the electrostatic latent image is developed, transferred, and fixed.

  As is apparent from FIGS. 39 to 41, by performing image exposure as shown in FIGS. 38 (a), 38 (b) and 38 (e), a basic shape with a flat upper end surface, It can be seen that a substantially chevron-shaped shape with a raised central portion and two substantially chevron-shaped shapes raised highly on the left and right sides and a recessed shape with a lowered central portion can be actually formed.

  However, the present invention is not limited to this, and there is a method of creating a latent image with an area gradation that is performed as a halftone expression. In this case, the cross-sectional profile of the latent image is not smooth inside one Braille dot. However, when the foamed toner as in the present invention is used, the toner itself undergoes volume expansion at the time of heat fixing, and details are buried (collapsed). Therefore, it is possible to reproduce the foamed toner cross-sectional profile of 1 dot Braille with a continuous curve.

  Further, the foamed toner cross-sectional profile of one Braille dot as described above can be changed by changing the ROS beam spot diameter, the ROS beam light amount, the ROS beam dot writing position, and the like. It is possible to obtain a braille image using a desired thermal foaming toner that matches the feeling of an individual person's finger.

  FIG. 42 is an electron micrograph showing the state of thermal deformation of the foaming agent-containing toner for forming a three-dimensional image as described above.

  In this case, the thermal expansion size of the foaming agent capsule and the thermal foaming (bubble) size of the toner are almost the same, and it can be seen that the medium to coarse foaming agent capsule contributes greatly to the thermal foaming of the toner.

  FIG. 43 is an electron micrograph showing a prototype toner for forming a three-dimensional image as described above.

  As a toner, it can be seen that a toner having a particle size of about 27 μm is good in terms of surface condition, toner particle shape, and the like.

  FIG. 44 shows the state of adhesion of foamed toner to the carrier.

  As is apparent from FIG. 44, it can be seen that the foamed toner contains more coarse powder (toner) released from the carrier than the normal toner.

FIG. 1 is a graph showing the relationship between the process speed (fixing speed) and the image height in the image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing an electrophotographic color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing an electrophotographic color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 4 is a schematic diagram showing toner formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 5 is a drawing-substituting photograph showing an electron micrograph of the toner formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 6 is a drawing-substituting photograph showing an electron micrograph of toner formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 7 is a schematic diagram showing an unfixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 8 is a drawing-substituting photograph showing an electron micrograph of an unfixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 9 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 10 is a schematic diagram showing a stereoscopic image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 11 is an electron micrograph showing a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 12 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 13 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 14 is an electron micrograph showing a normal fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 15 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 16 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 17 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 18 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 19 is a graph showing the relationship between the fixing temperature and the image height in the image forming apparatus according to Embodiment 1 of the present invention. FIG. 20 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 1 of the present invention. FIG. 21 is a graph showing the relationship between the paper basis weight and the fixed image height in the image forming apparatus according to Embodiment 1 of the present invention. FIG. 22 is a chart showing the types of recording paper having different basis weights, an electron micrograph showing a fixed toner image, and the thickness of the toner image together with the basis weight. FIG. 23 is a chart showing the types of recording paper having different basis weights, an electron micrograph showing a fixed toner image, and the thickness of the toner image together with the basis weight. FIG. 24 is a block diagram showing an image forming apparatus according to Embodiment 2 of the present invention. FIG. 25 is a graph showing the measurement results of the height of the toner image. FIG. 26 is a graph showing the relationship between the developing bias voltage and the toner image height. FIG. 27 is a block diagram showing a control circuit of the image forming apparatus according to Embodiment 2 of the present invention. FIG. 28 is a graph showing the relationship between the toner density and the height of the toner image after fixing. FIG. 29 is a graph showing the relationship between the fixing temperature and the height of the toner image. FIG. 30 is a graph showing the relationship between the process speed and the height of the toner image. FIGS. 31A and 31B are graphs showing the relationship between the fixing temperature and process speed and the height of the toner image, respectively. FIG. 32 is a block diagram showing a means for detecting the height of the toner image. FIG. 33 is a block diagram showing a means for detecting the height of the toner image. FIG. 34 is a block diagram showing an image forming apparatus according to Embodiment 3 of the present invention. FIG. 35 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 3 of the present invention. FIGS. 36A and 36B are graphs showing the measurement results of the heights of the unfixed toner image and the fixed toner image, respectively. FIG. 37 is a schematic diagram showing a braille image. 38A to 38E are schematic views showing an electrostatic latent image and a toner image, respectively. FIG. 39 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 3 of the present invention. 40 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by an image forming apparatus according to Embodiment 3 of the present invention. FIG. 41 is a drawing-substituting photograph showing an electron micrograph of a fixed toner image formed by the image forming apparatus according to Embodiment 3 of the present invention. FIG. 42 is a photo, which substitutes for a drawing, showing an electron micrograph of the foaming state of the toner added with a foaming agent. FIG. 43 is a drawing-substituting photograph showing an electron micrograph of the foaming agent-containing toner. FIG. 44 is a drawing-substituting photograph showing an electron micrograph of the state in which the foaming agent-containing toner adheres to the carrier.

Explanation of symbols

14: photosensitive drum, 15: developing device, 21: intermediate transfer belt, 30: fixing device, 40: toner particles, 41: binder resin, 42: foaming agent, 43: gas bubbles.

Claims (1)

A latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image formed on the image carrier by the latent image forming unit with toner to form a toner image. Transfer means for transferring the toner image onto a recording medium; and a toner image transferred onto the recording medium.
In an image forming apparatus provided with a fixing means for fixing,
When the toner containing at least a binder resin and a foaming agent is used as the toner, and the toner image formed by the toner is fixed on the recording medium by the fixing means, the fixing means is contained in the toner. 1 dot which is the smallest unit constituting one Braille character when forming a three-dimensional image on a recording medium and forming an electrostatic latent image on an image carrier by the latent image forming means By partially changing the latent image potential in one unit image consisting of two images , a three-dimensional shape having a height distribution in which the vicinity of one end rises rapidly and the other is gently inclined is formed. An image forming apparatus characterized by being made possible.

Images