JP4515175B2 - High frequency dielectric heat fixing device and image forming apparatus using the same - Google Patents

Description

  The present invention relates to an image fixing device and an image forming apparatus using the image fixing device, and more particularly to a fixing device using high-frequency dielectric heating and an image forming apparatus using the same.

  An image forming apparatus having functions such as a printer, a facsimile machine, and a copying apparatus is a recording medium such as recording paper, cloth, a plastic sheet, and an OHP sheet based on image information (recording information). The image containing characters, symbols, etc. is recorded on the paper.

There are various types of such image forming apparatuses. Among them, an image forming apparatus employing an ink jet method and an electrophotographic method is excellent in terms of image forming speed, ease of colorization, running cost, and the like. It is widely used in homes and offices.
In the ink jet system and the electrophotographic system, it is necessary to provide a fixing device for fixing ink or toner on a recording paper represented by paper. Further, such a fixing device is required to have characteristics such as a reduction in waiting time after power-on, high-speed fixing property, low power consumption, and prevention of scorching and burning of paper. Patent Documents 1 to 3 propose high-frequency dielectric heating devices as heat-fixing systems that satisfy such requirements.

  First, the configuration of an image forming apparatus using high frequency dielectric heating will be described with reference to FIG. The image forming apparatus includes a paper feeding unit (I), an image forming unit (II), a fixing unit (III), and a paper discharge unit (IV).

  In the paper feeding section (I), a recording medium (hereinafter referred to as recording paper 100) is fed from a paper feeding tray (not shown), and the recording paper 100 is conveyed to the image forming section (II) by a pair of rollers 101 ( Arrow A direction).

  In the image forming unit (II), the recording sheet 100 is conveyed (in the direction of arrow B) by the conveying belt 104 spanned between the driving roller 102 and the driven roller 103, and at the same time unfixed on the recording sheet 100. An image is formed and then conveyed to the fixing unit (III).

  Here, an example of an ink jet method is shown as the image forming method. Recording heads 105 </ b> A to 105 </ b> D that discharge black, cyan, magenta, and yellow inks are sequentially arranged in the conveyance direction of the conveyance belt 104. In addition, nozzles (line type recording heads) are formed in the recording heads 105a to 105D at predetermined intervals almost across the width of the recording paper 100 (in the direction perpendicular to the recording paper surface). Therefore, when the recording paper 100 is transported to the fixing unit (III) by the transport belt 104, a desired unfixed image is formed on the entire area of the recording paper.

In the case of such an ink jet method, particularly when a color image is formed, the amount of ink ejected from the recording heads 105a to 105D becomes large, and fixing by rapid ink drying under a normal environment becomes difficult. For this reason, if the ink is transported to the paper discharge tray of the paper discharge unit (IV) in a state where the ink is not dried (unfixed), the ink penetrates (back through) the back surface of the recording paper 100 during the transfer and the image Adverse effects such as deterioration of the image quality, or ink appearing on the back side of other recording paper in the paper discharge tray (show-through).
When the image forming system is an electrophotographic system, the image forming unit (II) forms an unfixed toner image on the recording paper 100 through known charging, exposure, and development processes.

  In the fixing unit (III), the recording paper 100 is conveyed (in the direction of arrow C) by the conveying belt 108 spanned between the driving roller 106 and the driven roller 107 to fix the image on the recording paper 100, and then the paper discharging unit. Transported to (IV).

  Here, as the ink heat fixing method, various methods are proposed in Patent Document 1 to Patent Document 3, but the high-frequency dielectric heating method proposed in Patent Document 3 can be suitably used. This is characterized in that the interval between the high-frequency applying means and the recording paper can be set short and uniformly, so that the heat fixing efficiency and fixing uniformity are excellent, and the high-frequency application region is highly flexible. Because there is.

  In this high-frequency dielectric heating and fixing method, a plurality of electrodes 109 (four examples are shown in FIG. 14) are arranged in the conveyance direction of the recording paper 100. At this time, these electrodes are arranged close to the unfixed image surface side of the recording paper 100 in order to improve the heating efficiency. These electrodes 109 are alternately applied with high-frequency voltages having different polarities from the high-frequency generation circuit 110. In addition, a control circuit 111 is provided for the purpose of ON / OFF of the high-frequency generation circuit 110 and voltage control. A high frequency voltage is applied between the electrodes 109 having different polarities, and the recording paper 100 is transported in an electric field generated between the electrodes. The ink itself, moisture in the recording paper 100, The recording paper 100 itself is heated. When the image forming method is an electrophotographic method, the toner itself, moisture in the recording paper 100, and the recording paper 100 itself are heated.

In such high-frequency dielectric heat fixing, it is necessary to prevent the conveyance belt 108 from being heated from the viewpoint of uniform image fixing. For this reason, as the conveyor belt 108, a resin such as polypropylene, polyethylene, or polytetrafluoroethylene having a small dielectric loss coefficient is used. In addition, as a method for holding the recording paper 100 on the conveyance belt 108, an air adsorption method can be suitably employed. Further, in such high-frequency dielectric heating and fixing, it is necessary to prevent leakage of the high-frequency electric field to the surroundings, and therefore, the shield member 112 must be disposed.

  In the paper discharge unit (IV), the recording paper 100 is conveyed (in the direction of arrow D) by a pair of rollers 113 to a paper discharge tray (not shown).

Japanese Examined Patent Publication No. 49-038171 Japanese Patent Laid-Open No. 52-020039 Japanese Patent Application Laid-Open No. 08-096951

  By the way, when a high-frequency dielectric heating method in which a plurality of electrodes are arranged in the recording paper conveyance direction as described above is used as a fixing device, dust adhered to the electrodes or dust adhered to the conveyance belt is caused between the electrodes and between the electrodes and the conveyance. There was a problem that discharge occurred between the belts. In addition, when an unfixed image formed by the inkjet method is heat-fixed, there is a problem that the unfixed image comes into contact between the electrodes and the ink between the electrodes is discharged. Further, when the recording paper is conveyed directly under the electrodes, there is a problem that the fixing quality varies if the distance between the electrodes and the recording paper varies.

  The present invention has been made in view of the above problems, and an object thereof is to provide a high-frequency dielectric heating fixing method capable of performing fixing processing reliably and at high speed, and an image forming apparatus using the fixing method. .

According to a first aspect of the present invention, there is provided a fixing device for fixing an image on a recording paper on which an unfixed image is recorded, and at least a pair of rod-shaped electrodes provided in a direction perpendicular to the recording paper conveyance direction parallel to the recording paper surface. the provided, a high-frequency power is applied to the electrode, unfixed images in a high-frequency dielectric heating fixing device for fixing on the recording paper, have to be the electrode a plate-shaped covering member formed by a small material of dielectric loss, the A rod-shaped electrode is embedded in the inside of the plate-shaped covering material and installed in the vicinity of the recording paper, and the plate-shaped covering member is arranged in a recording paper conveyance direction on a plate formed of a substance having a small electric loss. A plurality of ribs forming a conveyance guide for the recording paper are formed, a plurality of holes are provided at the tips of the ribs, and hot air that presses the recording paper against the opposite side is blown out .

According to a second aspect of the present invention, in the high-frequency dielectric heating device according to the first aspect , electrodes are arranged in a plate-like member that is a covering material having ribs formed on both sides of the recording paper, and hot air blows out to one of the covering materials. A hole is formed, and the position of the rib arranged on the other side is set to a position facing the hole of the rib that blows out the warm air .

According to a third aspect of the present invention, in the high-frequency dielectric heating device according to the first or second aspect , two rollers that are heated to a predetermined temperature downstream of the high-frequency dielectric heating portion and perform a fixing process with the recording paper interposed therebetween are arranged. It is characterized by that.

According to a fourth aspect of the present invention, there is provided a high-frequency dielectric heating and fixing device for fixing an image on a recording paper on which an unfixed image is recorded , wherein at least one or more pairs provided in a direction perpendicular to the recording paper conveyance direction parallel to the recording paper surface. In the high-frequency dielectric heating and fixing apparatus that applies a high-frequency power to the electrode and fixes an unfixed image on a recording sheet , the covering material is a film-like body that covers the periphery of the rod-shaped electrode. Is formed of a hollow pipe material, and a plurality of holes are formed on the surface side of the recording paper, and hot air that presses the recording paper against the opposite side surface is blown out from the holes .

According to a fifth aspect of the present invention, in the high-frequency dielectric heating and fixing apparatus according to the fourth aspect, two rollers that are heated to a predetermined temperature downstream of the high-frequency dielectric heating portion and perform a fixing process with the recording paper interposed therebetween are arranged. It is characterized by.

According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising: an image forming unit that forms an unfixed image; and a fixing unit that fixes the unfixed image, wherein the fixing unit is the high frequency device according to any one of the first to fifth aspects. An image forming apparatus using a dielectric heat fixing device.

  According to the present invention, it is possible to provide a high-frequency dielectric heat fixing method with high reliability and capable of uniform fixing, and an image forming apparatus using the fixing method.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

1 and 2 are views showing a high-frequency heating and fixing apparatus 200 according to the first embodiment of the present invention. In this example, unfixed toner T (or ink) is placed on the recording paper 100 conveyed to the conveying means including the driving roller 106, the driven roller 107, and the conveying belt. In this example, the electrode 210 is composed of four rod-shaped electrodes 211, 212, 213, and 214, and different polarities are applied to adjacent electrodes so that they are switched at a predetermined frequency. These rod-shaped electrodes 211, 212, 213, and 214 use a high frequency of 3 to 100 MHz. At that time, an electric field is generated between the electrode and the recording paper 100 (including toner and ink) and the adjacent electrode, and this alternates at high speed, so that the polarity of the object to be heated changes suddenly, and the toner is heated at that time. It is melted and fixed. If the recording paper 100 has ink, the ink is heated and dried and fixed on the recording paper 100.

  In this example, the rod-shaped electrodes 211, 212, 213, and 214 of the electrode 210 are conductors 211a, 212a, 213a, and 214a such as copper as shown in FIG. 2, and materials having low dielectric loss, such as polypropylene, polyethylene, and polytetrafluoro It is covered with insulating covering members 211b, 212b, 213b, 214b made of ethylene or the like. For this reason, even if dust adheres between the electrodes or the conveyor belt 108, no discharge occurs between the electrodes or between the electrode and the conveyor belt, and the system does not go down.

  In this example, four rod-shaped electrodes are used, but a larger number may be used. Further, the conveying means is not limited to the belt conveyance as shown in the figure.

  FIG. 3 is a cross-sectional view showing a high-frequency heat fixing device 220 according to the second embodiment of the present invention. Hereinafter, the same members are denoted by the same reference numerals in the drawings. In this example, in addition to the electrode 210 of the first embodiment, a roller type fixing device 230 shown in FIG. 4 is used in combination. In this roller type fixing device 230, the two pressure rollers 231 and 232 incorporate heaters 233 and 234, respectively. Here, the heaters 233 and 234 are intended to prevent the temperature of the toner from decreasing due to natural cooling after high-frequency heating. According to this example, the recording paper 100 is sandwiched between the heated pressure rollers 231 and 232, whereby the toner T is heated and softened at a predetermined temperature and crushed. In this way, when the unfixed image is toner, it is not only softened but also firmly attached to the recording paper 100 by being crushed, and the color toner has a predetermined color and glossiness due to the gap between the color toners being crushed. It is particularly effective because it also has an effect.

  In this example, the power consumption of the heaters 233 and 234 of the roller type fixing device 230 can be made smaller than that in a normal case where high frequency heating is not performed. The heating means of the roller type fixing device 230 may be other than the heater.

  FIG. 5 is a sectional view showing a high-frequency heat fixing device 240 according to the third embodiment of the present invention. In this example, the electrode 250 is formed by embedding rod-shaped electrodes 251, 252, 253, and 254 in a plate material 260 formed of a material having low dielectric loss, for example, polypropylene, polyethylene, or polytetrafluoroethylene. According to this example, the distance between the rod-shaped electrodes 251, 252, 253, and 254 does not change due to vibration or impact, and the distance changes due to adhesion of dust or the like and does not cause discharge. Further, the recording paper 100 is dried by heating, and the recording paper 100 can be prevented from entering between the electrodes generated by curling in one direction.

  FIG. 6 is a partially broken perspective view showing a high-frequency heat fixing device 270 according to the fourth embodiment of the present invention. In this example, as the electrode 280, ribs 292 are integrally provided on the side surface 291 of the plate material 290 similar to the plate material 260 described above facing the recording paper 100 so as to further improve the conveyance property of the recording paper along the conveyance direction. Is. According to the present example, since the friction between the electrode 280 and the recording paper 100 can be reduced, a better transport performance can be obtained.

  FIGS. 7A and 7B are views showing a high-frequency heat fixing apparatus 300 according to the fifth embodiment. FIG. 7A is a vertical sectional view of the apparatus, and FIG. 7B is a horizontal sectional view thereof. In this example, in order to make the distance between the electrode 310 and the recording paper 100 constant, air ejection holes 321 to 324 and 325 to 328 are opened at the tips of the ribs 311 formed in the plate-like member 320, and the hot air passage 329 is used. It is configured to blow out warm air. In this example, rod-shaped electrodes 251, 252, 253, 254 are built in the plate-shaped member diagram 320. FIG. 7A shows a state in which hot air is blown from the hot air passage 329 and is blown out from the air ejection holes 321 to 324, and FIG. 7B is a state in which hot air is blown from the hot air passage 329 and air at the tip of the rib 311. The state which is blowing out from the ejection holes 321 to 324 is shown.

  The reason why the air ejection holes 321 to 324 and 325 to 328 are provided at the tip of the rib 311 is that when the wind is blown from the root of the rib 311, the ribs on both sides become obstacles and the force to press the recording paper is weakened. This is because the distance up to 100 increases and the efficiency decreases. Further, the reason why the blown-out air is warm is that the temperature of the warmed recording paper 100 is not lowered. According to this example, the distance between the rod-shaped electrodes 251, 252, 253, 254 and the recording paper 100 is reliably kept constant, the voltage applied to the recording paper 100 is uniform, and the temperature distribution is uniform. It can be.

  FIG. 8 is a sectional view showing a high-frequency heat fixing device 330 according to the sixth embodiment of the present invention. In this example, an air ejection hole for blowing warm air is opened in the electrode 340 corresponding to the electrode 210 shown in the first embodiment. In this example, the rod-shaped electrodes 341, 342, 343, and 344 are made of conductors 341 a, 342 a, 343 a, and 344 a made of a hollow copper tube or the like, and the periphery of the conductors 341 a, 342 a, 343 a, and 344 a has a dielectric loss. Covering with a covering material 341b, 342b, 343b, 344b made of a low material, such as polypropylene, polyethylene, polytetrafluoroethylene, etc., hot air from the air passages 341c, 342c, 343c, 344c is applied to the air injection holes 314d, 342d. 343d and 344d. According to this example, the distance between the rod-shaped electrodes 341, 312, 343, 344 and the recording paper 100 can be kept constant. Further, the temperature drop of the recording paper 100 can be prevented.

  FIG. 9 is a sectional view showing a high-frequency heat fixing device 350 according to the seventh embodiment of the present invention. In this example, in addition to the electrode 210 shown in the first embodiment, an electrode 360 having the same configuration as the electrode 210 is disposed with the recording paper 100 and the conveyance belt 108 interposed therebetween. The electrode 360 is provided with rod-shaped electrodes 361, 362, 363, and 364.

  It is known that the fixing performance can be obtained not only by heating the toner and ink itself, but also by fixing the recording paper itself from the back side. This is because when the softened toner enters the recording paper fiber, the recording paper also enters the fiber more deeply if the temperature is high. The same can be said for ink fixing. According to this example, it is possible to heat from the back side of the recording paper 100 and to obtain better fixing performance. Of course, the voltage applied to the rod-shaped electrodes constituting the electrodes 210 and 360 can be changed.

  FIG. 10 is a cross-sectional view showing a high-frequency heat fixing device 370 according to the eighth embodiment of the present invention. Further, when toner is used as described above, the toner T needs to be crushed on the recording paper 100. Therefore, in this example, the roller type fixing device 230 is arranged in the configuration of the sixth embodiment. According to the high-frequency heat fixing device 370 according to this example, it is possible to sufficiently exhibit the color development performance.

  FIG. 11 is a sectional view showing a high-frequency heat fixing device 380 according to the ninth embodiment of the present invention. In this example, in addition to the electrode 250 shown in the third embodiment, an electrode 390 having the same configuration as the above electrode is provided with the recording paper 100 and the conveyance belt 108 interposed therebetween. In this example, the electrode 390 is configured by arranging rod-shaped electrodes 391, 392, 393, and 394 on the plate member 400.

  FIG. 12 is a perspective view showing a high-frequency heating and fixing device 410 according to the tenth embodiment of the present invention. In this embodiment, in addition to the electrode 280 shown in the above-described fourth embodiment, the recording paper 100 and the conveying belt 108 are used. An electrode 420 having the same configuration as that of the electrode 280 is provided. In this example, the electrode 420 is provided with a rod-like electrode on a plate material 422 on which a rib 421 is formed. According to this example, the friction between the recording paper 100 and the conveyance belt 108 and the high-frequency heating and fixing device 410 is remarkably reduced, and the conveyance performance is greatly improved.

  FIG. 13 is a sectional view showing a high-frequency heat fixing device 430 according to an eleventh embodiment of the present invention. In this example, in addition to the electrode 310 having the rod-shaped electrode 431 as in the high-frequency heating and fixing apparatus according to the above-described sixth embodiment, the rod-shaped electrode 442 is provided in the same manner as in the fourth embodiment with the recording paper 100 and the conveyance belt 108 interposed therebetween. An electrode 440 is provided. Further, in this example, the position where the rib 441 of the lower electrode 440 is disposed is the same position as the tip of the rib 311 of the upper electrode 310 having the air ejection holes 325 to 328 communicating with the warm air passage 329. I have to. In this example, the warm air jetted from the air ejection holes 432 of the upper electrode pushes the recording paper 100 and is pressed against the tips of the ribs 451 of the lower electrode 450, so that the recording paper 100 becomes flat, and as a result The distance of the recording medium becomes constant, and the temperature unevenness of the recording paper can be eliminated.

FIG. 1 is a perspective view showing a schematic configuration of a high-frequency heat fixing apparatus according to a first embodiment of the present invention. 1 is a perspective view showing a schematic configuration of a high-frequency heat fixing device according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a schematic configuration of a high-frequency heat fixing device according to a first embodiment of the present invention. It is sectional drawing which shows the high frequency heat fixing apparatus which concerns on the 2nd Example of this invention. It is sectional drawing which shows the other heating apparatus of the high frequency heating fixing apparatus which concerns on the 2nd Example of this invention. It is sectional drawing which shows the high frequency heat fixing apparatus which concerns on the 3rd Example of this invention. It is a partially broken perspective view which shows the high frequency heating fixing apparatus which concerns on the 4th Example of this invention. It is a figure which shows the high frequency heat fixing apparatus which concerns on 5th Example of this invention, (a) The longitudinal cross-sectional view of an apparatus, (b) is the cross-sectional view same as the above It is sectional drawing which shows the high-frequency heating fixing apparatus which concerns on the 6th Example concerning this invention. It is sectional drawing which shows the high frequency heating fixing apparatus which concerns on the 7th Example of this invention. It is sectional drawing which shows the high frequency heating fixing apparatus which concerns on the 8th Example of this invention. It is sectional drawing which shows the high frequency heating fixing device which concerns on the 9th Example of this invention. It is a perspective view which shows the high frequency heating fixing apparatus which concerns on the 10th Example of this invention. It is sectional drawing which shows the high frequency heating fixing apparatus which concerns on the 11th Example of this invention. 1 is a block diagram showing a schematic structure of an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Recording paper 101 Roller 102 Driving roller 103 Driven roller 104 Conveying belts 105a-105D Recording head 106 Driving roller 107 Followed roller 108 Conveying belt 109 Electrode 110 High frequency generating circuit 111 Control circuit 112 Shield member 113 Roller 114 Sensor 200 High frequency heating and fixing device 210 Electrodes 211, 212, 213, 214 Rod-shaped electrodes 211a, 212a, 213a, 214a Conductors 211b, 212b, 213b, 214b Cover member 220 High-frequency heating fixing device 230 Roller-type fixing device 231, 232 Pressure roller 233, 234 Heater 240 High-frequency heating Fixing device 250 Electrodes 251, 252, 253, 254 Rod electrode 260 Plate material 270 High frequency heating and fixing device 280 Electrode 290 Plate material 291 Opposite side surface 292 Rib 300 High-frequency heat fixing device 310 Electrode 311 Ribs 314d, 342d, 343d, 344d Air injection holes 320 Plate members 321, 322, 323, 324 Air injection holes 325, 326, 327, 328 Air injection holes 329 Hot air passage 330 High-frequency heat fixing Device 340 Electrode 341, 312, 343, 344 Rod electrode 341, 342, 343, 344 Rod electrode 341a, 342a, 343a, 344a Conductor 341b, 342b, 343b, 344b Cover material 341c, 342c, 343c, 344c Air passage 350 High frequency Heat fixing device 360 Electrode 361, 362, 363, 364 Bar electrode 370 High frequency heat fixing device 380 High frequency heat fixing device 390 Electrode 391, 392, 393, 394 Bar electrode 400 Plate material 410 High frequency heat fixing device 420 Electrode 30 high-frequency heat fixing device 432 the air ejection holes 440 electrode 441 the ribs 450 electrode 451 rib T toner

Claims (6)

A fixing device that fixes an image on a recording sheet on which an unfixed image is recorded, and includes at least a pair of rod-shaped electrodes provided in a direction perpendicular to the recording sheet conveyance direction in parallel to the recording sheet surface. In a high-frequency dielectric heating and fixing device that applies electric power and fixes an unfixed image on a recording sheet.
The electrodes have to be a plate-like covering material which is formed by a small material of dielectric loss,
A rod-shaped electrode is embedded in the plate-shaped covering material, and is installed in the vicinity of the recording sheet,
The plate-shaped covering member forms a plurality of ribs that form a conveyance guide for the recording paper side by side in a recording paper conveyance direction on a plate formed of a material with small electric loss,
A plurality of holes are provided at the tips of the ribs, and hot air that presses the recording paper against the opposite side is blown out.
A high frequency dielectric heating fixing device characterized by the above. On both sides of the recording paper , electrodes are arranged in a plate-like member that is a covering material having ribs formed therein, a hole through which hot air blows out is formed in one covering material, and the position of the ribs arranged on the other side is set to the above-mentioned temperature. In the position facing the hole of the rib that blows out the wind,
The high-frequency dielectric heating and fixing apparatus according to claim 1. Two rollers that are heated to a predetermined temperature downstream of the high-frequency dielectric heating portion and perform a fixing process with the recording paper interposed therebetween are arranged.
The high-frequency dielectric heating and fixing device according to claim 1 or 2 . A high-frequency dielectric heating and fixing device for fixing an image on a recording sheet on which an unfixed image is recorded, comprising at least a pair of rod-shaped electrodes provided in a direction parallel to the recording sheet surface and perpendicular to the recording sheet conveyance direction, In a high-frequency dielectric heating and fixing device that applies high-frequency power to an electrode and fixes an unfixed image on a recording sheet .
The covering material is a film-like body covering the periphery of the rod-shaped electrode,
The electrode is formed of a hollow pipe material, a plurality of holes are formed on the surface side of the recording paper, and hot air is blown out from the holes to press the recording paper to the opposite side surface.
High-frequency dielectric heating fixing device characterized in that. Two rollers that are heated to a predetermined temperature downstream of the high-frequency dielectric heating portion and perform a fixing process with the recording paper interposed therebetween are arranged.
The high-frequency dielectric heating and fixing device according to claim 4. Image forming means for forming an unfixed image, in an image forming apparatus having a fixing unit for fixing the unfixed image, said fixing means is either a high-frequency dielectric heating fixing equipment of claims 1 to 5 imaging equipment, characterized in that.