JP2010127966A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus reducing a carrier liquid infiltrating a recording medium while preventing the occurrence of a blister or high-temperature offset and stably conveying the recording medium. <P>SOLUTION: The image forming apparatus includes a nip fixing means for pressing a recording medium, on which an unfixed image is formed, while heating the recording medium, a non-contact heating means constructed movably in the direction facing the surface of the recording medium conveyed from the nip fixing means for heating the recording medium, which is passed through the nip fixing means, without contact, a driving means moving the non-contact heating means, and a control means controlling the driving means according to a deformation quantity of the recording medium by the nip fixing means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art An electrophotographic image forming apparatus that forms an electrostatic latent image on a photoconductor (photosensitive drum), adheres toner to the image, and transfers and fixes the image on paper or the like is widely used. In particular, in an image forming apparatus that requires higher image quality and higher resolution, such as an office printer for large-scale printing and an on-demand printing apparatus, a wet process using a liquid developer that has a small toner particle diameter and is less likely to cause toner image disturbance. Development methods are being used.

  In recent years, an image using a high-viscosity, high-concentration liquid developer composed of high-concentration dispersion of a solid toner composed of a resin and a pigment in an insulating liquid “carrier liquid” such as silicone oil. Forming devices have been proposed.

  When fixing an unfixed image formed with a liquid developer, it is necessary to remove the carrier liquid remaining on the recording medium.

  For example, a carrier liquid for forming an unfixed image on a recording medium is heated by a solvent precipitation unit to be deposited on the surface of the image, and the deposited carrier liquid is removed from the image surface by a solvent removal unit, and then heated and fixed. A method of fixing an image at a portion is disclosed (see Patent Document 1). Further, a method is disclosed in which a non-fixed image on a recording medium is heated in a non-contact manner using a non-contact heating means, and the deposited carrier liquid is removed from the image surface by a solvent removal means (see Patent Document 2).

  On the other hand, coated paper is used as the recording medium, but when the coated paper is heated to fix the image, the moisture contained in the coated paper is vaporized and expanded, causing a phenomenon called blistering that causes the coated paper to expand. There is a problem of doing.

In order to cope with such a problem, the recording medium is heated in the transport direction using a heat fixing device having a plurality of heat fixing members, and the heating temperature of the heat fixing member located at the most downstream is set to be the highest so that the blister There has been proposed a method in which an image is heated and fixed without generating (see Patent Document 3).
JP 2003-167456 A JP 2003-98864 A JP-A-11-202675

  In the wet development method, the carrier liquid remains infiltrated into the paper even after image fixing, and there is a problem that the image on the paper surface can be seen through from the back side of the paper. In order to reduce the amount of the carrier liquid that has penetrated into the paper, it is necessary to volatilize the carrier liquid by heating the paper at a temperature higher than the temperature at which the toner normally used for image fixing is melted and fixed.

  However, in the image forming apparatuses disclosed in Patent Documents 1 and 2 in which image fixing is performed by a heating and fixing unit that performs heating and pressurization after preheating, in order to volatilize the carrier liquid, the heating and fixing unit rapidly If heated, blisters may occur on the recording medium. Considering the heat resistance of the fixing member, the upper limit of heating at the heat fixing unit is about 220 ° C., and the carrier liquid cannot be volatilized in a short time.

  In the multi-stage fixing method using a plurality of heat fixing members disclosed in Patent Document 3, the occurrence of blisters can be avoided, but in order to volatilize the carrier liquid, it is necessary to lengthen the nip time, and the roller of the fixing device Increases, it becomes difficult to separate the roller and the paper. Further, if the nip time is lengthened, the toner is melted too much and a high temperature offset occurs, so that it becomes difficult to separate the fixing unit roller and the paper.

  The present invention has been made in view of the above problems, and provides an image forming apparatus capable of reducing carrier liquid penetrating into a recording medium while avoiding occurrence of blisters and high temperature offsets and stably conveying the recording medium. The purpose is to provide.

  In order to solve the above problems, the present invention has the following characteristics.

1. An image forming apparatus for heating and fixing an unfixed image on a recording medium formed using a liquid developer containing toner and a carrier liquid,
Nip fixing means for applying pressure while heating the recording medium on which the unfixed image is formed;
A non-contact heating unit configured to be movable in a direction opposite to the surface of the recording medium conveyed from the nip fixing unit and heating the recording medium that has passed through the nip fixing unit;
Driving means for moving the non-contact heating means;
Control means for controlling the driving means according to the deformation amount of the recording medium by the nip fixing means;
An image forming apparatus comprising:

2. The control means includes
A sheet detection sensor disposed to face the surface of the recording medium heated by the non-contact heating unit and outputting a signal corresponding to the distance from the surface of the recording medium that has passed through the nip fixing unit. 2. The image forming apparatus according to 1, wherein the driving unit is controlled based on an output of the sheet detection sensor.

3. The control means includes
3. The image forming apparatus according to 2, wherein the temperature of the non-contact heating unit is controlled based on an output of the paper detection sensor.

4). The control means includes
Input means for inputting information of the recording medium;
A table for storing information on the recording medium and a relationship between a distance between the non-contact heating means and the recording medium;
2. The image forming apparatus according to 1, wherein the driving unit is controlled by referring to the table based on information on the recording medium.

5). The table stores the relationship between the type of the recording medium and the temperature of the non-contact heating means,
The control means includes
5. The image forming apparatus according to 4, wherein the temperature of the non-contact heating unit is controlled by referring to the table based on information on the recording medium.

  According to the present invention, after passing through the nip fixing unit, the non-contact heating unit is moved so that the deformed recording medium and the non-contact heating unit are not in contact with each other, and the recording medium is heated in a non-contact manner. By doing so, it is possible to provide an image forming apparatus that can avoid the occurrence of blisters and high temperature offsets, stably transport the recording medium, and reduce the carrier liquid that has permeated the recording medium.

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

  FIG. 1 shows an example of the overall configuration of an image forming apparatus according to this embodiment. The overall configuration of the image forming apparatus will be described with reference to FIG. However, constituent elements mainly related to image fixing are shown, and other constituent elements are shown in a simplified manner.

  1 includes an input unit 95, a control unit 90, a photosensitive drum 1 as an image carrier, a charging device 2, an exposure device 3, a liquid developing device 4, a cleaning device 38, a roller fixing device 50, a sheet. The sensor 60, the non-contact heating part 6, the drive part 70, the power supply 71, the power supply 73, etc. are provided. The image forming apparatus 100 includes an intermediate transfer roller 5 as an intermediate transfer member and a secondary transfer roller 7.

  In FIG. 1, only one liquid developing device 4 is disposed, but a plurality of liquid developing devices 4 may be disposed for color image formation. The color development method, the presence / absence of intermediate transfer, and the like may be set arbitrarily, and an arbitrary arrangement configuration corresponding to the method can be taken.

  The input unit 95 includes a touch panel, operation buttons, various switches, and the like, and is an input unit according to the present invention that allows an operator to input various settings of the image forming apparatus 100.

  The control unit 90 includes a CPU 91 and a storage unit 92, and is a control unit of the present invention that controls the entire image forming apparatus 100 based on a program stored in the storage unit 92.

  The photosensitive drum 1 has a cylindrical shape with a photosensitive layer (not shown) formed on the surface thereof, and rotates in the direction of arrow A in FIG. On the outer periphery of the photosensitive drum 1, a cleaning device 38, a charging device 2, an exposure device 3, a liquid developing device 4, and an intermediate transfer roller 5 are sequentially arranged along the rotation direction of the photosensitive drum 1.

  The charging device 2 charges the surface of the photosensitive drum 1 to a predetermined potential.

  The exposure device 3 irradiates the surface of the photosensitive drum 1 with light to lower the charge level in the irradiated area, thereby forming an electrostatic latent image.

  The liquid developing device 4 develops the latent image formed on the photosensitive drum 1. That is, the liquid developer is conveyed to the development area of the photosensitive drum 1, and the toner contained in the liquid developer is supplied to the electrostatic latent image on the surface of the photosensitive drum 1 to form a toner image.

  In the developing process, a developing bias voltage having the same polarity as the toner is applied to the developing roller 41 of the liquid developing device 4 from a power source (not shown). Similarly, a difference in electric field is formed in balance with the potential of the latent image on the photosensitive drum 1 having the same polarity as the toner, and the toner in the developer is electrostatically adsorbed on the photosensitive drum 1 in accordance with the latent image. The latent image on 1 is developed.

  The intermediate transfer roller 5 is disposed so as to face the photosensitive drum 1 and rotates in the direction of arrow B while being in contact with the photosensitive drum 1. Primary transfer from the photosensitive drum 1 to the intermediate transfer roller 5 is performed at the nip portion between the intermediate transfer roller 5 and the photosensitive drum 1.

  In the primary transfer process, a transfer bias voltage having a polarity opposite to that of toner is applied to the intermediate transfer roller 5 from a power source (not shown). As a result, an electric field is formed between the intermediate transfer roller 5 and the photosensitive drum 1 at the primary transfer position, and the toner image on the photosensitive drum 1 is electrostatically attracted to the intermediate transfer roller 5. Transcribed above.

  When the toner image is transferred to the intermediate transfer roller 5, the cleaning device 38 removes the residual toner on the photoreceptor 1, and the next image formation is performed.

  The intermediate transfer roller 5 and the secondary transfer roller 7 are disposed so as to face each other with the recording medium 9 interposed therebetween, and rotate in contact with each other via the recording medium 9. Secondary transfer from the intermediate transfer roller 5 to the recording medium 9 is performed at the nip portion between the intermediate transfer roller 5 and the secondary transfer roller 7.

  The recording medium 9 is conveyed in the direction of arrow C to the secondary transfer position in accordance with the secondary transfer timing.

  In the secondary transfer process, a transfer bias voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 7 from a power source (not shown). As a result, an electric field is formed between the intermediate transfer roller 5 and the secondary transfer roller 7 and onto the recording medium 9 that has passed between the intermediate transfer roller 5 and the secondary transfer roller 7. The toner image is electrostatically adsorbed and transferred onto the recording medium 9. Reference numeral 40 in FIG. 1 denotes an image composed of the transferred toner and carrier liquid.

  The roller fixing device 50 includes a pair of fixing rollers 51 and a pressure roller 52 that are arranged to face each other and rotate in contact with each other. The fixing roller 51 and the pressure roller 52 are arranged in parallel in the vertical direction, and both ends are rotatably supported by bearing members (not shown), and the pressure roller 52 is provided by a pressure mechanism (not shown) using a spring or the like. Is pressed in the direction of the rotation axis of the fixing roller 51 and pressed against the lower surface of the fixing roller 51 with a predetermined pressure to form a pressure nip portion. The pressure roller 52 is rotationally driven by a motor 72 in a clockwise direction indicated by an arrow at a predetermined peripheral speed. The fixing roller 51 is rotated by the rotation of the pressure roller 52 by the pressure frictional force with the pressure roller 52 at the pressure nip portion. Note that the fixing roller 51 may be driven to rotate, and the pressure roller 52 may be driven to rotate.

  The fixing roller 51 and the pressure roller 52 have, for example, a silicon rubber layer as an elastic layer for securing a nip width on the outer periphery of a metal core having a good thermal conductivity such as aluminum, and a surface releasability. In order to enhance this, it is a roller provided with a release layer made of fluororesin such as PTFE or PFA having a thickness of 10 to 50 μm as the release layer.

  Heater lamps 53 and 54 are incorporated in the fixing roller 51 and the pressure roller 52, and the surface temperature is controlled to a desired temperature by the control unit 90. The roller fixing device 50 and the motor 72 are nip fixing means of the present invention.

  The recording medium 9 is heated and pressurized at the pressure nip portion of the roller fixing device 50, the toner is melted, a part of the carrier liquid is volatilized at the nip outlet, and a part is removed by the fixing roller. Most of the carrier liquid transferred to the toner remains in the toner image or in the recording medium 9. Note that the toner is melted also in the non-contact heating unit 6 disposed downstream, so that the toner may not be sufficiently fixed when it passes through the roller fixing device 50.

  The sheet detection sensor 60 is disposed on the non-contact heating unit 6 side with respect to the arrow C direction that is the conveyance direction of the recording medium 9, and corresponds to the distance from the surface of the recording medium 9 that has passed through the roller fixing device 50. The received signal is output to the control unit 90. As the sheet detection sensor 60, for example, an optical sensor such as a photo reflector, a magnetic sensor such as a Hall element, or an ultrasonic sensor can be used. Further, a mechanical sensor that contacts the recording medium 9 may be used.

  The non-contact heating unit 6 includes a heater 61 and a heat insulating cover 62 that covers the heater 61. The power source 71 is a power source 71 that supplies power to the heater 61. The controller 90 controls, for example, the output voltage of the power supply 71 based on the output of a temperature sensor (not shown) attached near the heater 61, and controls the surface temperature of the heater 61 to a desired temperature. The non-contact heating unit 6 and the power source 71 are non-contact heating means of the present invention.

  The recording medium 9 passing through the region facing the non-contact heating unit 6 is conveyed by a sheet conveying unit (not shown) arranged on the non-image surface side of the recording medium 9. The heater 61 may be a long-wavelength heater such as a ceramic heater in consideration of light absorption differences between black toner and yellow, magenta, cyan, and non-image portions. The heat insulating cover 62 for keeping the inside of the non-contact heating unit 6 at a high temperature may be made of a high heat insulating and high heat resistant material such as ceramic fiber.

  The drive unit 70 includes, for example, a pulse motor and a drive mechanism, and moves the non-contact heating unit 6 in the direction of the arrow D by a predetermined amount based on a command from the control unit 90. The control unit 90 is a driving unit of the present invention.

(Developer composition)
A liquid developer used for development will be described. In a liquid developer, colored toner particles are dispersed at a high concentration in a carrier liquid that is a solvent. In addition, additives such as a dispersant and a charge control agent may be appropriately selected and added to the liquid developer.

  As the carrier liquid, an insulating, non-volatile solvent at room temperature is used. Examples of the non-volatile solvent include silicon oil, mineral oil, paraffin oil, and the like.

  The toner particles are mainly composed of a resin and a pigment or dye for coloring. The resin has a function of uniformly dispersing pigments and dyes in the resin and a function as a binder when being fixed to the recording material.

  Examples of the resin that can be used include thermoplastic resins such as polystyrene resin, styrene-acrylic resin, acrylic resin, polyester resin, epoxy resin, polyamide resin, polyimide resin, and polyurethane resin. A plurality of these resins may be mixed and used.

  Commonly commercially available pigments and dyes used for coloring the toner can also be used. For example, carbon black, bengara, titanium oxide, silica, phthalocyanine blue, phthalocyanine green, sky blue, benzidine yellow, lake red D, etc. can be used as the pigment. Solvent red 27, acid blue 9, or the like can be used as the dye.

  As a method for adjusting the liquid developer, it can be adjusted based on a commonly used technique. For example, the resin and the pigment are melt kneaded using a pressure kneader, a roll mill or the like at a predetermined blending ratio and uniformly dispersed, and the obtained dispersion is finely pulverized by, for example, a jet mill. Further, by classifying the obtained fine powder with, for example, an air classifier, a colored toner having a predetermined particle diameter can be obtained.

  Subsequently, the obtained toner is mixed with an insulating liquid as a carrier liquid at a predetermined blending ratio. This mixture can be uniformly dispersed by a dispersing means such as a ball mill to obtain a liquid developer.

  The volume average particle diameter of the toner is suitably in the range of 0.1 μm or more and 5 μm or less. When the average particle diameter of the toner is less than 0.1 μm, the developability is greatly lowered. On the other hand, when the average particle diameter exceeds 5 μm, the quality of the image is degraded.

  The ratio of the toner particle mass to the liquid developer mass is suitably about 10 to 50%. If it is less than 10%, toner particles are liable to settle, and there is a problem with the stability over time during long-term storage. Further, in order to obtain a required image density, it is necessary to supply a large amount of developer, the carrier liquid adhering to the paper increases, and it must be dried at the time of fixing, and steam is generated, resulting in environmental problems. If it exceeds 50%, the viscosity of the liquid developer becomes too high, making it difficult to manufacture and handle.

  The viscosity of the liquid developer is preferably from 0.1 mPa · s to 10,000 mPa · s at 25 ° C. When it is 10,000 mPa · s or more, it becomes difficult to handle the developer such as stirring and feeding, and the burden on the apparatus for obtaining a uniform liquid developer is large.

  Next, the relationship between the heating time and the sheet temperature (the temperature of the recording medium 9) will be described with reference to FIG. FIG. 2 is a graph in which the relationship between the heating time t and the paper temperature Tp is plotted for each heating method.

Since the roller fixing device 50 has a high thermal efficiency for the recording medium 9, the rise of the paper temperature Tp is fast as shown in the graph indicated by a in FIG. 2. Therefore, when the nip time is increased, a blister is formed on the recording medium 9. Will occur. For example, when a coated paper having a basis weight of 80 g / m ² is used as the recording medium 9, when the coated paper is heated by the roller fixing device 50 having a roller surface temperature of 200 ° C., the paper temperature reaches 125 ° C. in a heating time of 50 msec. , Blister occurs.

  On the other hand, when non-contact heating is performed using the non-contact heating unit 6, since the temperature rise of the paper is slow as shown in the graph shown in FIG. Since the heat supply efficiency is low, the input energy (power consumption) for heating to a predetermined paper temperature Tp is increased.

  In the present invention, as shown by a graph shown in FIG. 2b, first, the paper temperature is efficiently increased by passing the paper through the roller fixing device 50, and then the non-contact heating by the non-contact heating unit 6 is necessary for reducing the carrier liquid. It is heated for a long time. Since the nip time of the roller fixing device 50 is set in a range where no blisters are generated at the set roller surface temperature, no blisters are generated. Further, the non-contact heating by the non-contact heating unit 6 is limited to only the time necessary for reducing the carrier liquid, so that the input energy (power consumption) can be reduced.

  Next, a phenomenon in which the recording medium 9 is deformed by passing through the roller fixing device 50 will be described. FIG. 3 is an explanatory diagram for explaining an example in which the recording medium 9 is deformed.

  FIG. 3A is a phenomenon generally referred to as “wagami”, and after passing through the roller fixing device 50, the recording medium 9 undulates as illustrated. FIG. 3B is a phenomenon generally referred to as curling, and the recording medium 9 is curled as shown in FIG.

  In consideration of energy saving, it is better to place the non-contact heating unit 6 and the recording medium 9 close to each other and lower the surface temperature of the heater 61. However, when the recording medium 9 is deformed, the recording medium 9 is connected to the heater 61. Depending on the temperature of the contact, burn, or heat source, there is a risk of ignition.

  On the other hand, if the distance between the heater 61 and the recording medium 9 is fixed so that the recording medium 9 does not come into contact with the heater 61 even when the recording medium 9 is deformed to the maximum extent, it is necessary to increase the surface temperature of the heater 61 and input energy (power consumption). Need to be increased.

  FIG. 4 is an explanatory diagram for explaining the operation when the recording medium 9 is deformed in the image forming apparatus 100 of the present invention, and FIG. 5 is a flowchart for explaining the control sequence of the first embodiment.

  FIG. 4A is an explanatory diagram for explaining the operation when the recording medium 9 is not deformed, and FIG. 4B is an explanatory diagram for explaining the operation when the recording medium 9 is deformed.

  The control sequence of the first embodiment will be described in the order of the flowchart of FIG.

  Note that the control unit 90 detects the leading edge of the recording medium 9 with a sensor (not shown) before passing through the roller fixing device 50, and starts the program of the flowchart of FIG. In the present embodiment, it will be described below that the output of the paper detection sensor 60 increases as the distance between the recording medium 9 and the paper detection sensor 60 decreases.

  S100: This is an initialization step.

The control unit 90 moves the non-contact heating unit 6 to an initial position close to the recording medium 9 shown in FIG. The control unit 90 controls the surface temperature of the heater 61 to a predetermined initial temperature T _0. In addition, the control unit 90 sets the value of the maximum output V _max stored in the storage unit 92 as an initial value.

S101: This is a step of determining whether or not V> V _max .

The control unit 90 compares the output V of the paper detection sensor 60 with the value of the maximum output V _max stored in the storage unit 92.

If V ≦ V _max (step S101; No), the process proceeds to step S107.

The output V of the paper detection sensor 60 is such less than or equal to the value of the maximum output V _max, the distance between the recording medium 9 and the paper detection sensor 60 is not approached. In this case, the process proceeds to step S107 without performing any particular process.

For _V> V _max, (step S101; Yes), the process proceeds to step S102.

Because paper output V of the sensor 60 exceeds the value of the maximum output V _max, the distance between the recording medium 9 and the paper detection sensor 60 becomes closer. In this case, the process proceeds to step S102 and subsequent steps.

  S102: This is a step of calculating the movement amount Y.

The controller 90 calculates the movement amount Y of the non-contact heating unit 6 based on the value of V−V _max . The movement amount Y is calculated using a calculation formula obtained in advance or a table indicating the relationship between V−V _max and the movement amount Y.

S103: a step of calculating the heater temperature _{T A.}

Control unit 90, based on the value of _{V-V max,} calculating the non-contact heating means temperature _{T A} of the non-contact heating section 6. Calculation of heater temperature T _A is performed by a table showing a previously obtained computation formula or is, or the relationship between the V-V _max amount of movement Y.

  S104: It is a step which drives the non-contact heating part 6.

  The control unit 90 instructs the drive unit 70 to move the non-contact heating unit 6 in the direction of arrow F by the movement amount Y calculated in step S102 as shown in FIG.

S105: _A step of controlling the temperature of the heater 61 to a predetermined temperature TA.

Control unit 90, together with the increase, for example, the output voltage of the power source 71, monitors the output of the temperature sensor of the non-contact heating section 6 performs control such heaters 61 reaches a predetermined temperature T _A.

S106: This is a step of setting V _max = V.

The control unit 90 stores V _max = V in the storage unit 92.

  S107: This is a step of determining whether or not the conveyance of the recording medium 9 is completed.

  The control unit 90 determines whether or not the recording medium 9 is present, whether or not the output V of the paper detection sensor 60 is equal to or less than a predetermined value.

  When the output V of the sheet detection sensor 60 is equal to or less than the predetermined value (step S107; Yes), the control unit 90 determines that the conveyance of the recording medium 9 is completed, and ends the process.

  When the output V of the sheet detection sensor 60 exceeds a predetermined value (step S107; No), the process returns to step S101.

  This is the end of the description of the control sequence of the first embodiment.

As described above, when the output V of the sheet detection sensor 60 becomes larger than the maximum output value V _max so far, the control unit 90 controls the drive unit 70 according to the output V and moves the non-contact heating unit 6 in the direction of arrow F. Move. Therefore, the recording medium 9 does not contact the heater 61.

The control unit 90, when the non-contact heating portion 6 is moved in the direction of arrow F, controls the power supply 71 so that the initial temperature T ₀ higher than temperature T _A in accordance with the position moved the temperature of the heater 61 Thus, most of the carrier liquid that has penetrated into the recording medium 9 passing under the heater 61 can be volatilized. When the temperature of the heater 61 is controlled according to the distance between the recording medium 9 and the heater 61 as described above, the heater 61 can be volatilized so that the carrier liquid can be volatilized even when the distance between the non-contact heating unit 6 and the recording medium 9 is the longest. Power consumption can be reduced compared to the case where the temperature is always set high.

  In the present invention, since the recording medium 9 is heated by radiation from the heater 61, the recording medium is stably conveyed while avoiding the occurrence of blisters and high temperature offsets, and most of the carrier liquid that has penetrated into the recording medium 9 is removed. Can volatilize.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 6 is an overall configuration example of the image forming apparatus 100 according to the second embodiment.

  The difference from the image forming apparatus 100 of the first embodiment described with reference to FIG. 1 is that the sheet detection sensor 60 is not provided in the second embodiment, and the table 93 is provided in the storage unit 92.

  In the second embodiment, focusing on the fact that the deformation amount of the recording medium 9 that has passed through the roller fixing device 50 falls within a predetermined range depending on the paper type, the non-contact heating unit 6 is moved according to the paper type. For example, a thin paper having a small basis weight Z is likely to be deformed when heated while being pressed by the roller fixing device 50. Therefore, it is necessary to increase the distance L between the heater 61 and the recording medium 9, and a thick paper having a large basis weight Z is deformed. Since it is difficult, the distance L may be small.

In the present embodiment, a distance L at which the heater 61 and the recording medium 9 do not come into contact with each other even when the recording medium 9 is deformed according to the basis weight Z is obtained in advance and stored in the table 93. The carrier liquid according to the distance L is are previously determined temperature T _A of the heater 61 can be reduced a predetermined amount.

Table 93 is data indicating the paper type for example as shown in Table 1, the distance between the recording medium 9 and the heater 61 L, the relationship between the temperature T _A of the heater 61.

  Other components are the same as those in the first embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 7 is a flowchart for explaining the control sequence of the second embodiment. The control sequence of the second embodiment will be described in the order of the flowchart of FIG.

  The control sequence of the second embodiment will be described in the order of the flowchart of FIG.

  Each time the user operates the input unit 95 to set the paper type, the control unit 90 starts the program of the flowchart of FIG.

  S201: This is a step of referring to the table 93.

Control unit 90, based on the paper type information of the recording medium 9 which is input from the input unit 95, refers to the table 93, obtaining information of the temperature T _A of the distance L and the heater 61. For example, if the paper type I is selected, the distance L is 60 mm, the temperature _{T A} of the heater 61 is 600 ° C..

  S202: It is a step which drives the non-contact heating part 6.

  The control unit 90 instructs the drive unit 70 to move the non-contact heating unit 6 so that the distance L obtained in step S201 is obtained. For example, in the case of paper type I, the non-contact heating unit 6 is moved in the direction of arrow F in FIG. 4 so that the distance L is 60 mm.

S203: _A step of controlling the temperature of the heater 61 to a predetermined temperature TA.

Control unit 90, together with the raise and controls the power supply 71 for example, the output voltage, monitors the output of the temperature sensor of the non-contact heating section 6 performs control such that the temperature T _A of the heater 61 is 600 ° C..

  This is the end of the description of the control sequence of the second embodiment.

Thus, in the second embodiment, the control unit 90 moves the non-contact heating unit 6 with reference to the table 93 corresponding to the paper type and basis weight. Therefore, the recording medium 9 can be prevented from contacting the heater 61 with a simple configuration. Further, by referring to the table 93, and controls the temperature T _A of the heater 61 to a predetermined temperature, the majority of the carrier liquid can be set to the optimum temperature for volatilizing a simple configuration, power consumption Can be reduced.

  As described above, according to the present invention, it is possible to provide an image forming apparatus capable of reducing carrier liquid penetrating into a recording medium while stably conveying the recording medium by avoiding occurrence of blisters and high temperature offsets. Can do.

1 is an explanatory diagram illustrating an overall configuration example of an image forming apparatus according to an exemplary embodiment. It is the graph which plotted about the relationship between the heating time t and the paper temperature Tp for every heating system. It is explanatory drawing explaining the example which the recording medium 9 deform | transformed. FIG. 6 is an explanatory diagram illustrating an operation when the recording medium 9 is deformed in the image forming apparatus 100 of the present invention. It is a flowchart explaining the control sequence of 1st Embodiment. 2 is an overall configuration example of an image forming apparatus 100 according to a second embodiment. It is a flowchart explaining the control sequence of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Exposure apparatus 4 Liquid developing device 5 Intermediate transfer roller 6 Non-contact heating means 7 Secondary transfer roller 9 Recording medium 50 Roller fixing device 51 Fixing roller 52 Pressure roller 53, 54 Heater lamp 60 Paper detection Sensor 61 Heater 62 Heat insulation cover 71 Power supply 72 Motor 90 Control part 82 Mag roller bias power supply

Claims (5)

An image forming apparatus for heating and fixing an unfixed image on a recording medium formed using a liquid developer containing toner and a carrier liquid,
Nip fixing means for applying pressure while heating the recording medium on which the unfixed image is formed;
A non-contact heating unit configured to be movable in a direction opposite to the surface of the recording medium conveyed from the nip fixing unit and heating the recording medium that has passed through the nip fixing unit;
Driving means for moving the non-contact heating means;
Control means for controlling the driving means according to the deformation amount of the recording medium by the nip fixing means;
An image forming apparatus comprising: The control means includes
A sheet detection sensor disposed to face the surface of the recording medium heated by the non-contact heating unit and outputting a signal corresponding to the distance from the surface of the recording medium that has passed through the nip fixing unit. The image forming apparatus according to claim 1, wherein the driving unit is controlled based on an output of the paper detection sensor. The control means includes
The image forming apparatus according to claim 2, wherein the temperature of the non-contact heating unit is controlled based on an output of the paper detection sensor. The control means includes
Input means for inputting information of the recording medium;
A table for storing information on the recording medium and a relationship between a distance between the non-contact heating means and the recording medium;
The image forming apparatus according to claim 1, wherein the driving unit is controlled with reference to the table based on information on the recording medium. The table stores the relationship between the type of the recording medium and the temperature of the non-contact heating means,
The control means includes
The image forming apparatus according to claim 4, wherein the temperature of the non-contact heating unit is controlled by referring to the table based on information on the recording medium.

Images