JP2007011212A - Image forming apparatus - Google Patents

Abstract

Heat transfer from a transfer fixing member to an image carrier can be reduced, and problems such as toner fixation to the image carrier and deterioration of a photosensitive layer can be suppressed in the secondary transfer fixing simultaneous method, and tertiary transfer fixing. An image forming apparatus capable of further energy saving in the simultaneous method is provided.
On an intermediate transfer belt 2, transparent particles 51 are supplied separately from toner by a particle supply device 50 so as to be scattered in an image forming region. The particles 51 are transferred from the intermediate transfer belt 2 to the transfer fixing roller 13 together with the toner image at the secondary transfer site, and transferred and fixed on the paper P together with the toner image at the tertiary transfer site. The particles 51 prevent contact between the intermediate transfer belt 2 and the transfer fixing roller 13 at the non-image portion at the secondary transfer portion, and reduce heat transfer from the transfer fixing roller 13.
[Selection] Figure 1

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a plotter, and more specifically, a simultaneous transfer and fixing method in which a toner image formed on an image carrier is finally transferred to a recording medium and simultaneously fixed. The present invention relates to an image forming apparatus.

In an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a printing machine, a copy or a recorded material is obtained by heating and fixing an unfixed image transferred and carried on a recording medium such as paper or sheet material. There are many things like this.
When fixing an image in such an apparatus, the unfixed image is heated and pressurized while conveying a recording medium such as a sheet material carrying the unfixed image sandwiched between the nips between the rollers, thereby unfixed image. The developer contained therein, in particular, the toner is fixed on the sheet material by melting and softening the toner and infiltrating the sheet material.
However, in such an image forming method, the toner layer is 3 to 15 μm after final fixing, whereas the paper is 60 to 200 μm thick and has a large heat capacity. Heating consumes a lot of energy to warm the paper and wastes power.

In order to improve this energy uneconomical effect, the toner and paper are separated from each other, and the toner is sufficiently heated and softened before contact with the paper. A “simultaneous method” has been proposed.
For example, in Japanese Patent Laid-Open No. 10-63121, a heat source is provided inside a driving roller of an intermediate transfer belt as a transfer fixing member, and a pressure roller is pressed against the driving roller via the belt to form a nip. Discloses a configuration in which the toner is heated in front of the nip, and the heated toner is transferred to a recording medium through the nip and fixed.

In this method (hereinafter referred to as “secondary transfer and fixing simultaneous method”), the secondary transfer from the intermediate transfer belt to the recording medium is performed not by electrostatic force but by the heat of fixing, so that the image quality is hardly deteriorated. Has advantages.
That is, in the method in which the toner image formed on the image carrier is transferred to the recording medium with electrostatic force, the surface of the recording medium is uneven, so the recording medium and the image carrier are not completely in contact with each other. Causes non-uniform gaps, resulting in disturbance of the transfer electric field and coulomb repulsion between the toners, which may cause disturbances in the formed image. In the “transfer and fixing simultaneous method” by thermal transfer, image disturbance is small.

However, in the configuration described in Japanese Patent Laid-Open No. 10-63121, the intermediate transfer belt is heated as much as the toner heating time, and is also heated in the belt thickness direction from the inner surface side, so that the heat retaining state of the belt is maintained. When the intermediate transfer belt next enters the primary transfer region, the plurality of image carriers (photoconductors) arranged along the belt surface are also heated by the belt holding heat, and the toner adheres to the photoconductor and is exposed to light. There was concern that problems such as layer degradation would occur.
In order to cope with this problem, the present applicant has proposed a simultaneous transfer and fixing method in the third transfer mode (hereinafter referred to as “third transfer and fixing simultaneous method”) in Japanese Patent Application Laid-Open No. 2004-145260.

This is because the toner image on the intermediate transfer member as the image carrier is secondarily transferred to the heated transfer fixing member, and a heating process of the toner alone is secured on the transfer fixing member. Third transfer and fixing are performed through a recording medium through a nip formed by opposing members.
According to this tertiary transfer fixing method, it is not necessary to directly heat the intermediate transfer member, so that energy saving (hereinafter simply referred to as “energy saving”) can be achieved, and toner adheres to the photosensitive member at the primary transfer portion or is photosensitive. Problems such as layer degradation can be suppressed.

Japanese Patent Laid-Open No. 10-63121 JP 2004-145260 A

Although the secondary transfer and fixing simultaneous method disclosed in Patent Document 1 can achieve high image quality as described above, problems such as adhesion of toner to the photoreceptor and deterioration of the photosensitive layer at the primary transfer site occur. There is concern to do. Further, since the amount of heat applied to the intermediate transfer member is required instead of reducing the amount of heat applied to the paper, improvement in the uneconomical energy cannot be expected.
In the simultaneous tertiary transfer fixing method disclosed in Patent Document 2, the toner heating process is ensured by an independent transfer fixing body that does not pass through the primary transfer site, so that energy saving and high image quality can be achieved as compared with the prior art. Problems such as toner sticking to the photoreceptor and deterioration of the photosensitive layer at the primary transfer site in the secondary transfer and fixing simultaneous method can be suppressed.

However, as a result of further intensive studies by the present inventors on the third transfer fixing simultaneous method, in the middle and high density portions, although the toner can be sufficiently heated and the paper is not heated so much, energy saving can be achieved. It has been found that the intermediate transfer member and the transfer fixing member come into contact with each other (highlight region), and the heat of the intermediate transfer member heats up the wasteful power. That is, it has been found that thermal diffusion to the intermediate transfer member occurs at the secondary transfer site.
Patent Document 2 proposes a configuration in which the contact pressure and distance of the secondary transfer site can be varied. However, it is difficult to partially reduce the contact pressure when the image portion is present in a strip shape in the sheet passing direction. Since the heat is transmitted in the form of a transfer fixing body, toner, and intermediate transfer body in the portion where the toner is present, the toner functions as a heat insulating layer, but in the portion where there is no toner, the transfer fixing body and the intermediate transfer body are directly Heat is conducted by contact.
For this reason, it has been conventionally considered difficult to reduce heat loss due to heat transfer to the intermediate transfer member regardless of the presence or absence of an image in the simultaneous third transfer fixing method.

  The present invention can reduce heat conduction from the transfer fixing member to the image bearing member, and can suppress problems such as toner adhesion to the image bearing member and deterioration of the photosensitive layer in the secondary transfer fixing simultaneous method. The main purpose of the simultaneous fixing method is to provide an image forming apparatus capable of further saving energy.

  In order to achieve the above object, according to the first aspect of the present invention, a toner image on an image carrier is transferred to a heated transfer fixing member, and a nip formed by the transfer fixing member and a member facing the transfer fixing member. In the image forming apparatus for fixing through the recording medium, a particle is interposed between the image carrier and the transfer fixing member to reduce heat conduction from the transfer fixing member to the image bearing member. To do.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image carrier is an intermediate transfer member.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect of the present invention, the image forming apparatus further includes a transfer unit that transfers the toner image to the transfer fixing member with an electrostatic force.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the particles are transparent and supplied so as to be scattered at least in non-image portions of the image forming region. It is characterized by that.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the particles are supplied so as to be transparent and to exist in substantially the entire image forming area.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the particles have an air layer therein.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the image forming apparatus includes a plurality of developing devices having different toner colors, and the lightest color toner among the toners is the above-described one. It is used as particles, and toner as the particles is supplied so as to be scattered in non-image portions of the image forming region.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the arrangement of the particles also serves as a tracking pattern for crime prevention.

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the particles contain a magnetic material, and magnetic force is applied so that the particles do not transfer to the transfer fixing body. It is characterized by controlling.

  According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the particles are carriers in a two-component developer housed in a developing device that forms the toner image. To do.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the supply amount of the carrier is adjusted by adjusting the relationship between the developing bias and the magnetic force of the developing roller of the developing device. To do.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the ninth to eleventh aspects, the magnetic force is adjusted at a predetermined timing, and the particles are separated from the image carrier. To do.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to the twelfth aspect, the image forming apparatus has a permanent magnet that generates a magnetic force, and the magnetic force is adjusted by the movement of the permanent magnet.

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to the third aspect, the particle diameter is larger than the maximum toner adhesion thickness, and the generation of toner dust during the transfer to the transfer fixing member is suppressed. The size is set to be possible.

  According to a fifteenth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the particle is transparent, and has poster mode setting means for supplying the particle to substantially the entire image forming area, and a poster When the mode is not set, a normal print mode is provided in which the mode is supplied so as to be scattered in non-image portions of the image forming area.

According to the first or second aspect of the present invention, since heat transfer from the transfer fixing member to the image carrier can be suppressed, in the simultaneous secondary transfer fixing method, the toner adheres to the image carrier and the photosensitive layer deteriorates. Such a problem can be suppressed, and further energy saving can be achieved in the simultaneous third transfer fixing method.
According to the third aspect of the present invention, it is possible to improve the transfer accuracy at the secondary transfer site in the third transfer fixing simultaneous method.
According to the fourth aspect of the present invention, the heat transfer suppression function can be obtained without affecting the image quality.
According to the invention described in claim 5, it is possible to realize high image quality with excellent water resistance and to obtain a high heat transfer suppression function.

According to invention of Claim 6, a high heat-transfer suppression function can be obtained.
According to the invention described in claim 7, the heat transfer suppression function can be obtained without increasing the number of consumables.
According to the invention described in claim 8, it is possible to obtain a heat transfer suppressing function without increasing the amount of consumables.
According to invention of Claim 9, while being able to reduce the amount of consumables as much as possible, the heat-transfer suppression function can be obtained.

According to the tenth aspect of the present invention, it is possible to obtain a heat transfer suppression function using a normal image forming operation without increasing the amount of consumables.
According to the invention described in claim 11, the heat transfer suppression function can be obtained with certainty.
According to the invention of the twelfth aspect, it is possible to prevent troubles due to particle retention.
According to invention of Claim 13, particle | grains can be controlled by a simple structure.
According to the fourteenth aspect of the invention, toner dust can be suppressed and high image quality can be realized.
According to the fifteenth aspect of the present invention, the image quality can be changed according to the user's preference, and the usability can be improved.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, the outline of the configuration and operation of a tandem type color copier as an image forming apparatus in the present embodiment will be described with reference to FIG. The color copying machine 1 includes an image forming unit 1A positioned at the center of the apparatus main body, a paper feeding unit 1B positioned below the image forming unit 1A, and an image reading unit (not shown) positioned above the image forming unit 1A. Have.
An intermediate transfer belt 2 as an intermediate transfer body having a transfer surface extending in the horizontal direction is disposed in the image forming unit 1A. The upper surface of the intermediate transfer belt 2 has a color complementary to the color separation color. A configuration for forming an image is provided. That is, the photoreceptors 3Y, 3M, 3C, and 3B as image carriers capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the intermediate transfer belt 2. Has been.

Each of the photoconductors 3Y, 3M, 3C, and 3B is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the charging device 4 that performs image forming processing in the rotation process, light A writing device 5, a developing device 6, a primary transfer device 7, and a cleaning device 8 are disposed as writing means. The alphabet added to each symbol corresponds to the color of the toner as in the photosensitive member 3. Each developing device 6 accommodates each color toner.
The intermediate transfer belt 2 is configured so as to be able to move in the same direction at the opposite position between the driving roller 9a, the transfer blade 9b as transfer means, and the driven roller 10 and the photoreceptors 3Y, 3M, 3C, 3B. Have. A cleaning device 11 for cleaning the surface of the intermediate transfer belt 2 is provided at a position facing the driven roller 10.
A particle supply device 50 for supplying transparent particles, which will be described later, is disposed near the downstream side of the photoreceptor 3Y in the belt movement direction.

The surface of the photoreceptor 3Y is uniformly charged by the charging device 4Y, and an electrostatic latent image is formed on the photoreceptor 3Y based on image information from the image reading unit. The electrostatic latent image is visualized as a toner image by a developing device 6Y containing yellow toner, and the toner image is primary-transferred onto the intermediate transfer belt 2 by a primary transfer device 7Y to which a predetermined bias is applied. Transcribed. The other photoconductors 3M, 3C, and 3B also form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 2 and superimposed.
The toner remaining on the photosensitive member 3 after the transfer is removed by the cleaning device 8, and the potential of the photosensitive member 3 is initialized by a neutralizing lamp (not shown) after the transfer to prepare for the next image forming process.

A fixing device 12 is provided in the vicinity of the driving roller 9a and the transfer blade 9b. The fixing device 12 includes a transfer fixing roller 13 as a transfer fixing member to which an unfixed toner image as an image on the intermediate transfer belt 2 is transferred, and a nip N (hereinafter referred to as “nip” or “transfer”). The pressure roller 14 is also used as a pressure member or a counter member for forming a nip. The transfer-fixing roller 13 is provided with an elastic layer such as silicone rubber on a cored bar formed of a metal such as iron, and a release layer is coated on the surface thereof.
The release layer needs to have releasability for holding toner and being in pressure contact with a sheet-like recording medium such as transfer paper, and is preferably excellent in heat resistance and durability. Therefore, the surface layer of the transfer fixing roller 13 is a heat-resistant release layer (tetrafluoroethylene resin (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin (PFA), and tetrafluoroethylene / hexafluoride). And at least one of propylene copolymer resin (FEP) and the like as a component).

Inside the transfer and fixing roller 13, a halogen heater 15 is provided as a heating means for heating the image on the transfer and fixing roller 13. A temperature controller (not shown) for controlling on / off of the halogen heater 15 based on a surface temperature obtained from a thermistor (not shown) provided in a non-image area (nip downstream portion) for measuring the surface temperature of the transfer fixing roller 13. And the temperature of the transfer fixing roller 13 can be controlled.
On the other hand, the pressure roller 14 is provided with an elastic layer 14b such as silicone rubber having a high hardness on the outer periphery of a cored bar 14a formed of a metal such as aluminum in the shape of a rod or a pipe in the same manner as the transfer fixing roller 13, and the surface layer thereof. A release layer such as Teflon (registered trademark) is formed.

  The paper feed unit 1B has a paper feed tray 16 on which sheets P as recording media are stacked and accommodated, and a paper feed roller 17 that feeds paper P in the paper feed tray 16 one by one in order from the top. A pair of transport rollers 18 that transports the fed paper P, and after the paper P is temporarily stopped and the oblique shift is corrected, the leading edge of the image on the transfer fixing roller 13 coincides with a predetermined position in the transport direction. A registration roller pair 19 is fed toward the nip N at timing.

  A toner image T (hereinafter, also simply referred to as “toner”) primarily transferred from the photoreceptors 3Y, 3M, 3C, and 3B onto the intermediate transfer belt 2 is applied to a transfer blade 9b by a bias applying unit (not shown). Secondary transfer is performed to the transfer fixing roller 13 by electrostatic force and adhesion force (thermal transfer) due to toner softening (including superposition of AC, pulse, etc.). A transfer method using only thermal transfer may be used.

Between the intermediate transfer belt 2 and the transfer fixing roller 13, a heat insulating plate 20 is provided as a heat shielding member or a heat movement suppressing member for suppressing heat radiation (heat movement) from the transfer fixing roller 13 to the intermediate transfer belt 2. It has been. The heat insulating plate 20 is formed in a shape having an opening so as to suppress heat radiation to the intermediate transfer belt 2 as much as possible without inhibiting secondary transfer from the intermediate transfer belt 2 to the transfer fixing roller 13. The fixing device main body and the image forming apparatus main body may be provided on either side.
A cooling member that removes heat from the intermediate transfer belt 2 between the transfer portion of the intermediate transfer belt 2 with respect to the transfer fixing roller 13 (the portion facing the transfer fixing roller 13) and the transfer portion with respect to the most upstream photoconductor 3B. A cooling roller 210 is provided. The cooling roller 210 is made of a material having high thermal conductivity, rotates in contact with the intermediate transfer belt 2, removes heat from the transfer fixing roller 13, and each of the photoreceptors 3Y, 3M, 3C, and 3Bk is heated. To prevent deterioration.

  The toner image T transferred from the intermediate transfer belt 2 to the transfer fixing roller 13 is independently heated on the transfer fixing roller 13 until it is fixed to the paper P at the nip N. Since a process of heating only the toner T in advance is sufficiently obtained, the heating temperature can be lowered as compared with the conventional method in which the toner T and the paper P are simultaneously heated. As a result of the experiment, it was confirmed that sufficient image quality can be obtained even when the temperature of the transfer fixing roller 13 is as low as 110 to 120 ° C.

As the binder resin used in the toner of the present invention, those having the following composition can be used as long as the characteristics of the toner of the present invention are satisfied.
For example, homopolymers of styrene such as polyester, polystyrene, poly p-chlorostyrene, and polyvinyltoluene, and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer Styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate Copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, Styrene-vinyl ethyl acetate Copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Examples thereof include styrene copolymers such as copolymers.

As shown in FIG. 2, the particle supply device 50 includes a casing 52 that houses transparent particles 51 made of synthetic resin, a sponge roller 53 that scoops up the particles 51, and a particle supply roller that receives the particles 51 from the sponge roller 53. 54, a blade 55 for regulating the particle layer thickness on the particle supply roller 54, a bias roller 56 disposed inside the intermediate transfer belt 2, and the like.
As the material of the particles 51, the same material as the binder resin for the toner can be used.
As shown in FIG. 3, the particles 51 are supplied so as to be scattered all over the image forming region. Since it is not supplied only to the non-image region, it is also scattered in the image region where the upper case letters (ABCDEFGHIJKLMN) are formed. However, since the particles 51 are transparent, the image quality is not affected.
In order to supply the particles 51 so as to be scattered all over the image forming region, the regulation of the layer thickness by the blade 55 may be adjusted, and the same principle as the variation in the toner supply amount by the developing roller can be performed.
Interspersed supply is also possible by adjusting the bias applied to the bias roller 56.
In the present embodiment, since the supply method in which the particles 51 are scattered all over the surface, the configuration and control are facilitated as compared with the case where the particles 51 are supplied only to the non-image region.

When the heat of the transfer fixing roller 13 is transferred to the intermediate transfer belt 2, useless energy is generated for maintaining the temperature of the transfer fixing roller 13. This makes it difficult for the high speed machine to maintain the temperature at 100V15A, and the productivity is lowered. This problem is remarkable in a portion where there is no toner image (background portion, between paper).
The image portion of an image forming apparatus for office use has an area ratio of 5 to 10%, and heat transfer is inevitably generated by the background portion.

As shown in FIG. 4, since the toner T functions as an interval holding member (spacer) at the image portion between the intermediate transfer belt 2 and the transfer fixing roller 13, a gap g is secured and a heat insulating function is obtained. It is done. Similarly, in the non-image region, the gap g is secured by the presence of the particles 51, and a heat insulating function is obtained.
Therefore, even if a non-image portion (background portion) such as so-called white solid exists, the intermediate transfer belt 2 and the transfer fixing roller 13 are not in direct contact, and heat transfer from the transfer fixing roller 13 to the intermediate transfer belt 2 is performed. Is suppressed. Similarly, heat transfer due to direct contact is prevented between the sheets (between the image forming area and the image forming area of the next sheet).
The particles 51 are secondarily transferred to the transfer and fixing roller 13 in the same manner as the toner T while serving as a heat insulating member, and then thirdarily transferred and fixed on the paper P in the same manner as the toner T.

The intermediate transfer belt 2 and the transfer fixing roller 13 are in contact with each other in a light pressure state. Here, “light pressurization” refers to the secondary transfer nip pressure under the following conditions.
Secondary transfer nip pressure <force for burying gap particles (particle 51, toner T) in the surface of transfer fixing roller 13 <force for breaking gap particles

In the present embodiment, as shown in FIG. 5, the diameter t2 of the particles 51 is larger than the maximum toner adhesion thickness t1, and the size can suppress the generation of toner dust during transfer to the transfer fixing roller 13. Is set to Specifically, the particle size of the particles 51 is set to be twice or less (t1 + 50 μm or less) of the toner maximum adhesion thickness t1.
If the particles 51 are too large, the heat insulation is improved, but the toner transfer dust increases and the image quality deteriorates. As described above, the transfer to the transfer fixing roller 13 uses the electrostatic force in addition to the thermal transfer. This is because the surface layer of the toner image can be transferred by thermal transfer, but the lower layer is largely transferred by electrostatic transfer.
In the case of electrostatic transfer, if the gap g is too large, toner dust is generated, and thus an upper limit value for suppressing this is required. This value can be determined by experiment according to conditions, and the above value is an example.

The particles 51 may be densely supplied (arranged) over substantially the entire image forming area (second embodiment). In this case, heat transfer can be suppressed most. In addition to this, a high image quality such as a silver salt photograph having high gloss and a wide color reproduction range can be obtained. Further, since the paper surface is covered with a transparent resin, a printed matter having excellent water resistance such as a poster can be obtained. In other words, it is possible to cope with special applications simply by adjusting the supply amount of the particles 51.
FIG. 6 shows experimental results of the heat insulation effect when particles having various particle diameters are arranged with an area occupancy of 0 to 100%.
100% of course shows high heat insulation. Further, at the same occupied area ratio, the larger the particle diameter, the smaller the power loss. If the image is glossy like a photographic image using transparent toner, the most energy saving is achieved.

As shown in FIG. 7, for example, the operation panel 70 of the image forming apparatus is provided with a poster mode setting key 71 as a poster mode (photo mode) setting means for supplying the transparent particles 51 to almost the entire image forming area. May be arbitrarily selected (third embodiment).
When the poster mode setting key 71 is pressed, for example, a message that “poster mode is executed” is displayed on the liquid crystal display unit 72.
When the poster mode setting means 71 is not pressed, the normal print mode is performed in which the particles 51 are supplied so as to be scattered in the non-image portions of the image forming area.

As the particle | grains 51, as shown in FIG. 8, it is good also as a structure which has the air layer 57 inside (4th Embodiment). In this way, since the ratio of the air layer in the gap g between the intermediate transfer belt 2 and the transfer fixing roller 13 can be increased, the heat transfer can be further suppressed.
Among the toners currently used for color image formation, yellow toner, which is the lightest color, is difficult to visually recognize even if it is scattered in non-image areas, and does not affect the image quality.
From this point of view, the lightest color toner (here, yellow toner) that does not affect the image quality may be used as the particles 51 (fifth embodiment).
In the present embodiment, when a latent image is formed on the photoreceptor 3Y, a dot pattern of particles (yellow toner) is written also in a non-image portion and developed together with a predetermined image by the developing device 6Y.
If the existing image forming means is used in this way, the number of consumable varieties is not increased as compared with the case where transparent particles are used, and it is not necessary to newly provide a supply device for the particles 51, thereby simplifying the configuration. Cost reduction can be realized.
Similarly, the image forming means can be used to suppress heat transfer between sheets.

In the case of using transparent particles and in the case of using the above light color toner, it is possible to analyze the tracking pattern of crime prevention such as securities that have been conventionally incorporated (which can be analyzed by which manufacturer or lot of machine copied and printed) The arrangement of the particles 51 may also be used (sixth embodiment).
In this case, since the particles 51 are consumed as originally necessary, there is an advantage that heat transfer can be reduced with almost no increase in the amount of consumables.

Next, a seventh embodiment will be described based on FIG. 9 and FIG. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and unless otherwise specified, description of the configuration and functions already described is omitted, and only the main part will be described (the same applies to other embodiments below).
1 differs from the configuration of FIG. 1 in that the transfer fixing roller 13 is heated from the outside by a heating source 58 having a reflecting plate, is covered with a plate 59 to suppress heat dissipation of the transfer fixing roller 13, and enters the nip. For example, a heater 25 is provided as a recording medium heating means for heating the surface of the paper P before printing, and a permanent magnet 60 as a magnetic source is arranged in the vicinity of the transfer blade 9c so as to be movable in the direction of arrow 61. .

Further, the particle 51 ′ in the present embodiment contains a magnetic substance, and its behavior can be controlled by a magnetic force. Therefore, the particle 51 ′ may be a magnetic material itself. Hereinafter, the particles 51 ′ are also referred to as “magnetic particles”.
In this embodiment, as the magnetic particles 51 ′, a carrier that flows out of the developing device in a normal developing process in image formation using a two-component developer is used. That is, in the two-component development, there is a so-called “carrier adhesion” phenomenon, and it is unavoidable that a small amount of carrier flows out. Therefore, the outflowed carrier is used as it is as the magnetic particle 51 ′.
As shown in FIG. 9, the magnetic particles 51 ′ supplied on the intermediate transfer belt 2 remain with magnetic force in the vicinity of the upstream side of the secondary transfer portion in the belt movement direction. The magnetic force of the permanent magnet 60 is set so as to prevent the magnetic particles 51 ′ from being transferred to the transfer fixing roller 13.
The amount of the magnetic particles 51 ′ at the secondary transfer site increases with time, but the magnetic particles 51 ′ are more than necessary by periodically moving the permanent magnet 60 to the left in the drawing to weaken or disappear the magnetic force. So that it does not stay. That is, the amount of the magnetic particles 51 ′ at the secondary transfer site can be adjusted by the movement of the permanent magnet 60.

The movement control of the permanent magnet 60 is performed by the control means 63 shown in FIG. 10 via the magnet movement means 68 such as a solenoid.
The control means 63 is a microcomputer having an I / O interface 64, a CPU 65, a ROM 66, and a RAM 67. In the ROM 66 or the RAM 67, an optimum time interval (for example, for moving the permanent magnet 60) obtained in advance through experiments or the like is stored. A predetermined sheet passing interval) is stored.
When the magnetic force is weakened, the magnetic particle 51 ′ finishes its role as a spacing member and falls downward from the intermediate transfer belt 2 by its own weight and is accommodated in the receiving member 62.

By using a carrier for two-component development, the types of consumables are not increased. The particle diameter was confirmed at 20 to 50 μm, but it was confirmed that the influence on the image quality was very small if it was 50 μm or less. Since the magnetic particles 51 'are collected, transparency is not required.
When the amount of carrier is small in the interspersed arrangement of the particles 51 ′, the developing bias is strengthened, the magnet force of the developing roller of the developing device is relatively weakened, and the carrier moves to the photoreceptor together with the toner. It is sufficient to adjust the flow rate so that the outflow amount of the carrier is intentionally increased.
Further, the particles 51 ′ containing the magnetic material or the magnetic material itself may be separately supplied by a dedicated supply device without using the carrier coming out of the developing device.

In each of the above embodiments, the endless belt-shaped intermediate transfer belt 2 is used as the image carrier, but the same can be applied to a configuration using a cylindrical intermediate transfer body 26 as shown in FIG. Embodiment).
Also, as shown in FIG. 12, the same can be applied to a configuration using a belt-like transfer fixing member 41 (the ninth embodiment). The transfer fixing member 41 includes a heating roller 33 having a halogen heater 32 therein, a roller 42 having a cored bar 42a and an elastic layer 42b, and a transfer fixing belt 43 wound around the heating roller 33 and the roller 42. .
A nip N is formed by the pressure contact of the pressure roller 44 having the core metal 44 a and the elastic layer 44 b to the roller 42, and a weak pressure portion Na is formed by the tension of the transfer fixing belt 43 against the pressure roller 44. In FIG. 12, reference numeral 73 denotes a driving roller.
In each of the above embodiments, an example of the “third transfer fixing simultaneous method” is shown. However, the “secondary transfer fixing simultaneous method” as disclosed in Patent Document 1 can be similarly implemented. In this case, the particles are supplied between the photosensitive member and the intermediate transfer member (intermediate transfer belt). Specifically, the particle supply device 50 is disposed upstream of the photosensitive member located on the most upstream side in the belt moving direction.

1 is a schematic side view of an image forming apparatus according to a first embodiment of the present invention. It is a schematic sectional drawing of a particle supply apparatus. FIG. 6 is a plan view of output paper in a state where transparent particles are scattered all over the surface. It is a figure which shows the heat-transfer reduction function in a secondary transfer site | part. It is a figure which shows the magnitude | size of the particle | grain with respect to the thickness of a toner layer. It is a graph which shows the relationship between a particle occupation area rate and a loss electric power. It is a general | schematic top view which shows the poster mode setting means in 3rd Embodiment. It is a schematic sectional drawing of the particle | grains in 4th Embodiment. It is a principal part front view in 7th Embodiment. It is a control block diagram in a 7th embodiment. It is a principal part front view in 8th Embodiment. It is a principal part front view in 9th Embodiment.

Explanation of symbols

2 Intermediate transfer belt as image carrier 6Y, 6M, 6C, 6B Developing device 13 Transfer fixing roller as transfer fixing member 14 Pressure roller 51, 51 ′ particle as opposed member 57 Air layer 60 Permanent magnet 71 Poster mode Setting means P Paper as recording medium

Claims (15)

In an image forming apparatus for transferring a toner image on an image bearing member to a heated transfer fixing member and fixing the toner image through a recording medium in a nip formed by the transfer fixing member and a member facing the transfer fixing member.
An image forming apparatus, wherein particles are interposed between the image carrier and the transfer fixing member to reduce heat conduction from the transfer fixing member to the image carrier. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the image carrier is an intermediate transfer member. The image forming apparatus according to claim 2.
An image forming apparatus comprising transfer means for transferring the toner image to the transfer fixing member with electrostatic force. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the particles are transparent and supplied so as to be scattered at least in non-image portions of an image forming region. The image forming apparatus according to claim 2 or 3,
An image forming apparatus, wherein the particles are supplied so that the particles are transparent and exist in substantially the entire image forming area. The image forming apparatus according to any one of claims 1 to 5,
An image forming apparatus, wherein the particles have an air layer therein. The image forming apparatus according to any one of claims 1 to 3,
A plurality of developing devices having different toner colors are used, and the lightest color toner among these toners is used as the particles, and the toner as the particles is supplied so as to be scattered in non-image portions of the image forming region. An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the arrangement of the particles also serves as a tracking pattern for crime prevention. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the particles contain a magnetic material, and are controlled by a magnetic force so that the particles do not transfer to the transfer fixing member. The image forming apparatus according to claim 9.
An image forming apparatus, wherein the particles are carriers in a two-component developer housed in a developing device for forming the toner image. The image forming apparatus according to claim 10.
An image forming apparatus comprising: adjusting a supply amount of the carrier by adjusting a relationship between a developing bias and a magnetic force of a developing roller of the developing device. 12. The image forming apparatus according to claim 9, wherein
An image forming apparatus, wherein the particles are detached from the image carrier by adjusting a magnetic force at a predetermined timing. The image forming apparatus according to claim 12.
An image forming apparatus comprising a permanent magnet for generating a magnetic force, wherein the magnetic force is adjusted by movement of the permanent magnet. The image forming apparatus according to claim 3.
2. An image forming apparatus according to claim 1, wherein the particle diameter is set to be larger than a toner maximum adhesion thickness and to a size capable of suppressing generation of toner dust during transfer to the transfer fixing member. The image forming apparatus according to claim 2 or 3,
If the particles are transparent and have a poster mode setting means for supplying the particles to substantially the entire image forming area, and if the poster mode is not set, the particles are supplied so as to be scattered in non-image regions of the image forming area. An image forming apparatus that executes a normal print mode.

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