JP3562229B2 - Multicolor printing method and multicolor printing apparatus using electrophotography - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multicolor printing method and a multicolor printing apparatus using an electrophotographic method, and particularly to a transfer quality improving technique in electrophotographic printing using an intermediate transfer member.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, printing using electrophotography has been performed as one of printing techniques. In this electrophotography, charges are given to the surface of a photoreceptor by corona discharge (charging), and then a subject image is projected on the surface of the photoreceptor (exposure). As a result, the charge is neutralized in the exposed portion of the photoconductor, and a charge pattern (latent image) is formed on the photoconductor surface. When a developer (toner or the like) that is frictionally charged is sprayed on the charge pattern, the charge is electrostatically attracted to form a toner image (development). Further, the toner image is transferred to a printing medium, and the toner is melted to be fixed on the printing medium, whereby an electrophotograph can be completed.
[0003]
In the case of single-color printing, good printing can be performed with the above-described configuration. However, in the case of performing multi-color printing (color printing), the toner images of each color are sequentially transferred to an intermediate transfer member, and A color toner image is synthesized before transfer to a printing medium. Then, the color toner images are collectively transferred to the printing medium. This is because, when superimposing and transferring the toner images of the respective colors, the accuracy of the alignment between the intermediate transfer body and the photosensitive body, which are relatively positioned in the apparatus, is higher than that of the printing medium conveyed by the conveyance mechanism or the like. This is because the alignment accuracy between the photoconductor and the photoconductor is higher. In addition, since the surface of the intermediate transfer member can be made flexible, recording media other than ordinary recording paper, such as recording paper, metal, and resin, as well as three-dimensional objects such as cans and boxes having curved surfaces, as well as ordinary recording paper. The transfer of the toner image can also be performed.
[0004]
By the way, in the case of transfer printing using the intermediate transfer body, when a powdery toner image is transferred to a printing medium, the printed image itself is composed of dots and the particles are unclear and prominent. There is. After the toner is transferred to the printing medium, the printing medium is heated to fix the toner. At this time, the roughness of the particles is slightly improved but is not sufficient.
[0005]
Therefore, for example, Japanese Patent Application Laid-Open No. 49-78559 proposes a printing apparatus that heats an intermediate transfer member, melts toner on the intermediate transfer member, and then transfers the toner to a printing target. . According to this apparatus, the toner is melted before the transfer, the particle interface is eliminated, and the toner image itself becomes a smooth image having a non-particle transparent feeling (gloss), so that the transferred image can be sharpened. Japanese Patent Application Laid-Open No. 3-63758 discloses that the heating temperature on the intermediate transfer member is controlled to be equal to or lower than the toner melting temperature in consideration of thermal deterioration and thermal efficiency of the intermediate transfer member of the apparatus. There has been proposed a toner image transfer / fixing apparatus that performs transfer printing on a pre-heated printing medium by melting the toner in a printing medium. According to this apparatus, it is possible to transfer a toner image while reducing the load on the printing apparatus itself.
[0006]
[Problems to be solved by the invention]
However, when the toner particles are completely melted on the intermediate transfer member as in the above-described printing apparatus, a toner image having a transparent feeling with no noticeable particles can be formed. If it is too much, the transferred image will bleed during the transfer or the fused image will fall off the intermediate transfer member, or the peeling will be incomplete (the bonding force of the toner image will be reduced and some of the torn toner will be transferred to the intermediate transfer member). However, such problems as unstable transfer occur.
[0007]
In addition, when controlling the temperature of each member, the temperature control is complicated because the temperature capacity of each printing medium is different, and the melting of the toner is liable to occur. However, it was not possible to completely eliminate problems such as blurring or incomplete peeling of the fused image from the intermediate transfer member.
[0008]
Furthermore, when the above-mentioned problem is applied to transfer printing of a color image in which a plurality of colors are superimposed, there has been a problem that faithful color reproduction of an original image due to bleeding, incomplete peeling or the like cannot be performed.
[0009]
Further, when the toner is melted, when the printing medium is a plastic container made of polyethylene, polypropylene, or the like, the container often has a heat deformation temperature lower than the melting temperature of the toner, so that the container is not transferred when the toner image is transferred. There is also a problem of deformation.
[0010]
The present invention has been made in view of the above circumstances, and forms a smooth color toner image by detoning the toner, and completely removes the toner image from the intermediate transfer body to perform faithful color reproduction. An object of the present invention is to provide a multicolor printing method and a multicolor printing apparatus using an electrophotographic method capable of obtaining a high quality transfer print image.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the configuration of the present invention is based on a single-color latent image formed on the surface of a photoreceptor, and performs electrostatic transfer while superposing a plurality of color toner powders on an intermediate transfer body. Forming a color toner image, and in a multicolor printing method using an electrophotographic method of printing the color toner image on a printing medium, a plurality of superimposed color toner powders are melted on the intermediate transfer body. A melting step of forming a single molten toner layer;Is 10 ^Four The molten toner layer is used to form a semi-molten color film having an apparent viscosity higher than poise.On the intermediate transfer memberForciblycoolingDoThe method includes a cooling step and a transfer step of transferring the color film to a printing medium.
[0012]
Here, the toner colors that constitute the color toner image are, for example, colors such as yellow, magenta, cyan, and black, and the laminated color toner particles are heated and melted by a heating unit such as an infrared heater, for example. Is formed. Then, after melting, the molten toner layerForciblyCooled,10 ^Four Has higher apparent viscosity than PoiseIt is brought into a semi-molten state (film state immediately before complete solidification).
[0013]
According to this configuration, the interface between the toner particles is eliminated by melting, and a transparent and smooth image is formed, and a cooled, color toner image can be formed as a color toner image in a semi-molten state with a binding force. Peeling from the body is performed smoothly, and stable complete transfer can be performed.
[0015]
Also,CompulsionTypicalcoolingIsThis is achieved by supplying a medium such as cooling water, cooling oil, or cooling air into the intermediate transfer body, or by supplying cooling air to the surface of the intermediate transfer body.
[0016]
Therefore,According to this configuration, the melted toner layer once melted can be quickly turned into a semi-melted color film.
[0017]
Further, the configuration of the present invention is characterized in that, in the method, a preheating step of heating the printing medium before the transfer of the color film is further provided.
[0018]
Here, the preheating temperature of the printing medium varies depending on the material of the printing medium, but is, for example, 80 ° C. in the case of a steel can. According to this configuration, the adhesion between the color film in a semi-molten state and the printing medium is improved, and good transfer can be performed.
[0019]
Further, the configuration of the present invention forms a color toner image by electrostatically transferring a plurality of color toner powders on the intermediate transfer member while overlapping each other, based on the single-color latent image formed on the photoconductor surface, In a multicolor printing apparatus using an electrophotographic method for printing the color toner image on a printing medium, the intermediate transfer body melts the color toner powder superimposed after the formation of the color toner image to form a single fused toner layer. A fusing station for forming the fusing station, and the fusing toner layer provided downstream of the fusing station.Is 10 ^Four The molten toner layer is used to form a semi-molten color film having an apparent viscosity higher than poise.ToForciblycoolingDoIt is characterized by including a cooling station and a transfer station for transferring the color film to a printing medium.
[0020]
According to this configuration, the interface between the toner particles is eliminated by melting, and a transparent and smooth image is formed, and a cooled, color toner image can be formed as a color toner image in a semi-molten state with a binding force. Peeling from the body is performed smoothly, and stable complete transfer can be performed.
[0021]
Further, the configuration of the present invention is characterized in that the apparatus further comprises a preheating station for heating the printing medium before the transfer of the color film.
[0022]
According to this configuration, the adhesion between the color film in a semi-molten state and the printing medium is improved, and good transfer can be performed.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described with reference to the drawings. In the present embodiment, an example will be described in which multicolor printing using four color toners (yellow, magenta, cyan, and black) using electrophotography is performed on the side surface of a cylindrical can.
[0024]
FIG. 1 is an explanatory schematic diagram centering on an intermediate transfer member of a multicolor printing apparatus 10 of the present embodiment. The multicolor printing apparatus 10 is formed by a CPU 12 for controlling the entire apparatus, electrophotographic units 14Y, 14M, 14C, and 14K provided for each toner color, and the electrophotographic units 14Y, 14M, 14C, and 14K. Drum-like intermediate transfer body 16 for superimposing the toner images of the respective colors, a transport device (not shown) for transporting, for example, a can 18 as a printing medium to a printing position, and a toner (not shown) for fixing the toner image transferred to the can. It is composed of a fixing device and the like. The electrophotographic units 14Y, 14M, 14C, and 14K are arranged for each toner color (for example, yellow (Y), magenta (M), cyan (C), and black (K)). 20M, 20C, 20K, photoconductors 22Y, 22M, 22C, 22K, charging devices 24Y, 24M, 24C, 24K, developing devices 26Y, 26M, 26C, 26K, cleaning devices 28Y, 28M, 28C, 28K, etc. I have. The intermediate transfer member 16 has a substantially drum shape, and has a volume resistivity of 10 on the surface of the metal layer 16a.³-10¹²About Ωcm, preferably 10⁵-10¹⁰A conductive elastic body of Ωcm, for example, a conductive rubber 16b is provided around.
[0025]
The transfer printing of a color toner image will be described with reference to FIG. Image information recognized by an image reading device or an external input device (not shown) while performing color separation using a color filter or the like is sequentially exposed to the electrophotographic units 14Y, 14M, 14C, and 14K for each color based on an instruction from the CPU 12. (For yellow), 20M (for magenta), 20C (for cyan), and 20K (for black). Since the process for each color is the same, the transfer principle will be described using yellow (Y) as an example. The exposure device 20Y irradiates a laser beam based on yellow image information to form a latent image on the photoconductor 22Y. The photoconductor 22Y is formed of, for example, a resin in which vapor-deposited amorphous silicon, vapor-deposited memorphous selenium, or zinc oxide or an organic photoconductor is scattered on a drum-shaped conductor, and a charge layer is formed on the surface by a charging device 24Y. It is formed. When the charge layer is irradiated with the laser beam from the exposure device 20Y, the charges are neutralized in the exposed portion, and a charge pattern (latent image) is formed on the surface of the photoconductor 22Y. When a developer (yellow toner) that is frictionally charged is sprayed on the charge pattern by the developing device 26Y, electrostatic attraction occurs to the charge and a yellow toner image is formed (development).
[0026]
In this embodiment, a voltage supply source (electrodes in this embodiment) for applying a predetermined voltage is connected to the metal layer 16a disposed on the surface of the hollow drum-shaped intermediate transfer body 16. When the metal layer 16a is supplied with a voltage, an electrostatic force corresponding to the voltage is formed on the conductive rubber 16b provided around the surface of the intermediate transfer body 16. With this electrostatic force, the developed yellow toner image is transferred and held on the intermediate transfer body 16. Hereinafter, similarly, a latent image forming process, a developing process, a transfer holding process, and the like are performed for magenta (M), cyan (C), and black (K), and a color toner image of a plurality of colors is formed on the surface of the intermediate transfer body 16. Is formed.
[0027]
The features of the present embodiment include a fusing station where the intermediate transfer body 16 melts the color toner images obtained and held from the electrophotographic units 14Y, 14M, 14C and 14K, and a half-cooled color toner image that has been melted once. It has a cooling station for forming a color film in a molten state, and a transfer station for transferring the formed color film to a printing medium, and transfers the cooled and semi-molten color film to the printing medium.
[0028]
In the present embodiment, it is preferable that the melting of the toner is efficiently performed after the superposition of the four color toner images is completed and the color toner image is formed. Therefore, the fusing station 30 is formed along the surface of the intermediate transfer body 16 at a position downstream of the electrophotographic unit 14K. The fusing station 30 has, for example, an infrared heater, and heats the surface of the intermediate transfer body 16 to 140 ° C., which is the melting temperature of the toner (which is appropriately selected depending on the type of toner to be used). The color toner image held on the surface (conductive rubber 16b) is melted.
[0029]
On the other hand, a cooling device 32 for cooling the surface of the intermediate transfer body 16 is built in the intermediate transfer body 16. In the embodiment shown in FIG. 1, the cooling device 32 circulates cooling water or cooling oil whose temperature is controlled to the surface metal layer 16 a of the intermediate transfer body 16 to melt the surface of the intermediate transfer body 16. The temperature is maintained lower than the heating temperature in the station 30 (for example, 40 to 50 ° C.). That is, after passing through the melting station 30, the intermediate transfer body 16 is cooled. In the present embodiment, the downstream side of the melting station 30 is defined as a cooling station 34. Accordingly, the melted toner layer formed by melting at the melting station 30 is cooled at the cooling station 34 to be a semi-molten color film.
[0030]
The color film comes into contact with a can 18 which is a printing medium which is sequentially conveyed by a conveying device (not shown) at a transfer station 36 and is transferred onto the surface of the can 18. The can 18 is pre-heated by a pre-heating station 38 provided on the conveyance path of the conveyance device before the transfer of the color film. This preheating temperature prevents the color film from coming into contact with the printing medium, thereby preventing the interface temperature of the color film from dropping below a predetermined temperature (cooling temperature) and hindering good transfer. The preheating temperature varies depending on the material of the printing medium, but is, for example, 80 ° C. (a suitable temperature range of 60 ° C. to 130 ° C.) for the steel can 18. Further, when the printing medium is a plastic container or film such as polyethylene or polypropylene, in consideration of the thermal deformation of the container or film, the preheating temperature is preferably, for example, the upper limit temperature is more limited than the can 18. The temperature range is set to about 60C to 110C.
[0031]
The preheating station 38 has, for example, an infrared heater and heats the can 18 being transported. In the case of the can 18, by preheating to a temperature higher than the cooling temperature, the color film in a semi-molten state is again melted (softened), and the adhesion to the surface of the can 18 is improved, so that good transfer can be performed. it can.
[0032]
In FIG. 1, the timing of supplying each image information to the exposure devices 20Y, 20M, 20C, and 20K, the timing of generating a laser beam, the rotation speed of the photoconductors 22Y, 22M, 22C, and 22K, the intermediate transfer body 16, It is necessary to synchronize all operations such as the supply timing of 18, but these are all performed by the CPU 12.
[0033]
The structure of the cooling device 32 provided on the intermediate transfer body 16 of the multicolor printing device 10 and a specific structure around it will be described with reference to FIGS. As shown in FIG. 2, the intermediate transfer body 16 has a hollow drum shape, and a ring-shaped outer peripheral portion 40 a and a cylindrical central portion 40 b are connected by a connecting member 42. A central shaft 44 is fixed to the central portion 40b, and is connected to an output shaft 46a of a motor (preferably, a motor that can be feedback-controlled) 46 that is a rotation drive source of the intermediate transfer member 16, Is driven to rotate precisely. A fixed plate 50 having a convex portion 50a for holding a ring-shaped voltage supply electrode 48 for generating electrostatic force is fixed on the surface of the intermediate transfer body 16 coaxially with the central axis 44. The fixing plate 50 is fixed to a frame (not shown) of the multicolor printing apparatus 10. That is, the intermediate transfer body 16 is arranged to be rotatable with respect to the voltage supply electrode 48.
[0034]
A power supply device (not shown) that applies a predetermined voltage to the rotating intermediate transfer body 16 is connected to the protrusion 50a. Also, fixed to the tip of the arm 52 implanted in the connection member 42Was doneA contact 56 is provided at the tip of the leaf spring 54.handI have. The contact 56 always contacts the voltage supply electrode 48 so that a constant voltage can be constantly applied to the surface metal layer 16a regardless of the rotational position of the intermediate transfer body 16. In the case of the present embodiment, the cooling medium of the cooling device 32 described above passes through the metal layer 16a to perform a cooling operation. A bearing or the like is inserted into a contact portion between the fixed plate 50 and the central shaft 44 so that the intermediate transfer body 16 can rotate smoothly with respect to the fixed plate 50.

[0035]
As described above, the surface temperature of the intermediate transfer member 16 is controlled by circulating cooling water (or cooling oil) through the surface metal layer 16 a of the intermediate transfer member 16 at the tip of the central shaft 44. A fluid distribution / recovery path 58 of the cooling device 32 is formed. A temperature controller 60 for controlling the temperature of the cooling water and a pump 62 for sending the temperature-controlled cooling water to the metal layer 16a of the intermediate transfer body 16 are arranged outside the intermediate transfer body 16. The cooling water that has passed through the metal layer 16a is collected in the tank 64, and is again supplied to the temperature controller 60. Therefore, a cooling water circulation system is formed by the temperature controller 60, the pump 62, the metal layer 16a, and the tank 64.
[0036]
FIG. 3 is a partially enlarged view of the fluid distribution / recovery path 58 at the distal end of the central shaft 44. A water supply pipe 66 through which the temperature-adjusted cooling water having a large diameter passes is disposed at the center of the center shaft 44, and a plurality (for example, 12) of drain pipes 68 through which the used cooling water having a small diameter passes are disposed around the water supply pipe 66. Have been. An end opening 66a of the water supply pipe 66 and an end opening 68a of the drain pipe 68 are connected to connection flow paths 70 and 72 formed in an annular shape around the central shaft 44, respectively. A cooling water supply pipe 74 extending from the pump 62 is connected to a part of the connection flow path 70, and a cooling water drain pipe 76 toward the tank 64 is connected to a part of the connection flow path 72. Therefore, the end opening 66 a of the rotating central shaft 44 always receives the supply of the temperature-controlled cooling water from the connection passage 70, and the end opening 68 a always drains the used cooling water through the connection passage 72. be able to. In addition, a seal member 78 is inserted into a connection portion between the connection flow paths 70 and 72 and the central shaft 44 so that the cooling water does not leak.
[0037]
At the other end position 66 b of the water supply pipe 66, the water supply pipe 66 is divided into a plurality of (for example, twelve) branch pipes 80 in order to distribute cooling water to the entire circumference of the intermediate transfer body 16. Each branch pipe 80 passes through the surface metal layer 16 a of the intermediate transfer body 16, cools the surface, is charged into the drain pipe 68 of the central shaft 44 via the recovery pipe 82, and is further guided to the tank 64. Since the number of the branch pipes 80 is limited by space, it is preferable that the entire metal layer 16a is uniformly cooled by further branching or meandering at the metal layer 16a.
[0038]
FIG. 4 is a sectional view of a portion where the recovery pipe 82 is connected to the drain pipe 68. In FIG. 4, a central part is a water supply pipe 66. As described above, the cooling water is always supplied to the surface metal layer 16a of the intermediate transfer body 16, and the surface temperature of the intermediate transfer body 16 is maintained at a predetermined temperature. Thus, a color film can be easily formed. In the present embodiment, as shown in FIG. 1, it is necessary to cool the molten toner layer melted at about 140 ° C. at the melting station 30 to about 40 ° C. at a downstream position of the melting station 30. Is, for example, 20 ° C to 25 ° C.
[0039]
As described above, the intermediate transfer body 16 maintained at the predetermined temperature by the circulation of the cooling water holds the toners of the respective colors on the surface thereof by electrostatic force and melts the toners of the respective colors held by the melting station 30 to form the toner. A fused toner layer with less noticeable particles is formed. Then, the molten toner layer that has passed through the melting station 30 is forcibly cooled from the melting temperature by the intermediate transfer body 16 maintained at a predetermined temperature to become a semi-molten color film. Once the toner is melted, the interface between the toner particles is eliminated, the entire surface becomes glossy, and a non-particle smooth color toner image is obtained. Further, by being cooled and becoming a color film in a semi-molten state, the bonding as a toner image is completed, the separation from the intermediate transfer body 16 is facilitated, and a high-quality color image with faithful color reproduction of the original image is obtained. The color toner image can be transferred to the printing material can 18.
[0040]
Incidentally, when heating and melting the toner stacked and held on the intermediate transfer body 16 and further cooling it to a semi-molten state, the optimum heating temperature and the optimum cooling temperature differ depending on the type of toner. Similarly, when a color film in a semi-molten state is transferred to a printing material, there is a difference in heat absorption by the printing material (difference in heat capacity and preheating temperature of the printing material). The cooling temperatures for forming films are also different. Therefore, it is desirable that the criterion for heating and cooling of the toner in the present embodiment is determined by the viscosity of the toner at the time of melting and at the time of semi-melting (apparent viscosity by a Koka flow tester). The apparent viscosity measurement by the Koka type flow tester means that a melt flow test is performed under the condition of a load of 10 kgf using a nozzle having a diameter of 1.0 mm and a length of 10 mm, and the apparent viscosity at each temperature is determined based on a change in the amount of extrusion. This is a measuring method for determining the viscosity of the polymer.
[0041]
FIG. 5A is a logarithmic graph showing the relationship between the temperature of the toner stacked and held on the intermediate transfer member 16 and the apparent viscosity at that time. As shown, apparent viscosity 10⁴(Poise), apparent viscosity 10⁴(Poise) lower viscosity (eg 10²-10⁴The heating temperature of the toner is set so that the⁴(Poise) higher viscosity (eg 10⁴-10⁶It is preferable to set the cooling temperature so as to be approximately poise. It should be noted that the lower the cooling temperature and the higher the viscosity of the color film, the better the separation from the intermediate transfer member 16 is performed. Therefore, as shown in FIG. 5B, after the toner temperature is raised to Ta at the melting station 30 (see FIG. 1), the toner temperature is excessively cooled to Tb1 at the cooling station. Thereafter, if the temperature of the color film is raised to the optimum toner temperature Tc for transfer by preheating the printing medium (can 18), re-softening is performed at the time of transfer to the printing medium, and the color film is cooled at the time of cooling. Good transfer can be performed even if the viscosity is increased to some extent. When the printing medium is made of a material that is easily deformed by heat, the cooling temperature in the cooling station is set to a toner temperature Tb2 higher than the optimum toner temperature Tc for transfer, as shown in FIG. If the temperature is lowered to the toner temperature Tc by the temperature drop effect due to the contact with the printing medium, good transfer can be performed while preventing thermal deformation of the printing medium.
[0042]
FIG. 6 is a schematic diagram showing another configuration for cooling the molten toner layer. In the example shown in FIG. 6, the color toner image 84 stacked and held on the intermediate transfer body 16 by electrostatic force is melted at the melting station 30 including an infrared heater or the like to form a molten toner layer 86. This is the same as the example shown in FIG. In the case of FIG. 6, a cooling blower 88 is arranged along the outer peripheral surface of the intermediate transfer body 16 at a position downstream of the fusing station 30 to cool the molten toner layer 86 from the outside and form a color film 90 in a semi-molten state. are doing. The formed color film 90 is transferred to the tube 18 preheated by the mandrel heater 92.
[0043]
By employing such an external cooling structure, it is possible to obtain the same effect as in the example of FIG. 1 while facilitating the structure inside the intermediate transfer body 16. Further, if the internal cooling shown in FIG. 1 and the external cooling shown in FIG. 6 are combined, more effective cooling processing can be performed. In the method using the cooling air as shown in FIG. 6, it is necessary to provide an isolation wall or the like or adjust the blowing direction so that the cooling air does not interfere with the melting process of the melting station 30.
[0044]
In the cooling structure shown in FIGS. 1 to 4 described above, the configuration in which the whole of the intermediate transfer body 16 is cooled from the inside of the intermediate transfer body 16 is shown, but only the downstream position of the melting station 30 of the intermediate transfer body 16 is changed from the inside. The same effect can be obtained even when the cooling is performed partially. The medium passing through the cooling circulation system inside the intermediate transfer body 16 is arbitrary, and may be cooling air or the like.
[0045]
In the present embodiment, a cylindrical can (aluminum, steel, or the like) has been described as an example of a printing target. However, the printing target is arbitrary, for example, a plastic bottle, cup, tube, or the like, or a sheet. Similar effects can be obtained with paper and cloth (including those wound in rolls), films (including laminated films formed of plastic, metal foil, etc.), bags and paper cups made of laminated films, etc. Can be.
[0046]
Further, the structure shown in each figure is an example, and if a color film in a semi-molten state can be formed on the intermediate transfer member by forming a molten toner layer and cooling, the structure is arbitrary, and a similar effect can be obtained. Can be.
[0047]
Furthermore, in the present embodiment, color transfer in which four color toners are superposed has been described as an example. However, the toner color and the number of colors (including a single color) to be used are arbitrary, and the same effects as those in the above-described embodiment can be obtained. Can be.
[0048]
【The invention's effect】
According to the present invention, the toner is heated and melted on the intermediate transfer member to form a molten toner layer, thereby making it possible to eliminate the interface between toner particles. An image can be formed. Further, by cooling the molten toner layer on the intermediate transfer member to form a color film in a semi-molten state, the separation from the intermediate transfer member becomes smooth, and faithful color reproduction of the original image on the printing medium is achieved. Complete transfer can be performed.
[Brief description of the drawings]
FIG. 1 is an explanatory schematic diagram illustrating a multicolor printing method according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating an intermediate transfer member and a cooling device of the multicolor printing apparatus according to the embodiment of the present invention.
FIG. 3 is a partially enlarged view of a fluid distribution / recovery path at a front end portion of a center axis of an intermediate transfer body of the multicolor printing apparatus according to the embodiment of the present invention.
FIG. 4 is a cross-sectional view of a portion where a collection pipe on a central axis of an intermediate transfer body of a multicolor printing apparatus according to an embodiment of the present invention is connected to a drain pipe.
FIG. 5 is an explanatory diagram showing the relationship between the viscosity of the toner and the heating / cooling temperature of the multicolor printing apparatus according to the embodiment of the present invention.
FIG. 6 is an explanatory diagram illustrating another cooling structure of the multicolor printing apparatus according to the embodiment of the present invention.
[Explanation of symbols]
10 multicolor printing device, 14Y, 14M, 14C, 14K electrophotographic unit, 16 intermediate transfer body, 16a metal layer, 16b conductive rubber, 18 cans, 30 melting station, 32 cooling device, 34 cooling station, 36 transfer station, 38 Preheating station.

Claims (4)

Based on the single-color latent image formed on the photoreceptor surface, a color toner image is formed by electrostatically transferring a plurality of color toner powders while being superposed on an intermediate transfer body, and forming the color toner image. In a multicolor printing method using electrophotography to print on
A fusing step of fusing the superimposed color toner powders on the intermediate transfer body to form a single fused toner layer;
A cooling step of forcibly cooling the molten toner layer on the intermediate transfer member so that the molten toner layer becomes a semi-molten color film having an apparent viscosity higher than 10 ⁴ poise ;
A transfer step of transferring the color film to a printing medium,
A multicolor printing method using electrophotography, comprising: The method of claim 1, wherein
further,
A multicolor printing method using electrophotography, comprising a preheating step of heating a printing medium before transfer of the color film . Based on the single-color latent image formed on the photoreceptor surface, a plurality of color toner powders are electrostatically transferred while being superimposed on an intermediate transfer member to form a color toner image. In a multicolor printing device using electrophotography to print on
The intermediate transfer member,
A fusing station for fusing the superimposed color toner powder after forming the color toner image to form a single fused toner layer;
Provided downstream of the fusing station, wherein the fusing toner layer ^Four A cooling station for forcibly cooling the molten toner layer so as to obtain a semi-molten color film having an apparent viscosity higher than poise;
A transfer station for transferring the color film to a printing medium,
A multicolor printing apparatus using electrophotography, comprising: The device according to claim 3,
further,
A multicolor printing apparatus using an electrophotographic method, comprising a preheating station for heating a printing medium before transfer of the color film.

Images