JPH10340013A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device capable of stably outputting an image by making spacer particles intervene at least between the photoreceptor and the intermediate transfer body of a primary transfer part so that a fine gap is formed. SOLUTION: A spacer particle supplying means mechanically or electrostatically supplies the spacer particles (s) on the surface of a film material 80 in contact or non-contact state against a follower roller. Then, the particle (s) is carried to the primary transfer part X by the driving of the film 80, superposed between the photoreceptor 1 and the intermediate transfer body 8, and forms the fine gap. As a result, contaminant (p) adhering to the surface of the film 80 is prevented from adhering to the surface of the photoreceptor with hardly stirring a toner image (t) formed on the photoreceptor 1. The spacer particle (s) must be larger than the thickness of the contanimant (p) adhering to the surface of the film 80, that is, average particle size is 1 to 50 μm, desirably 3 to 20 μm, and it is desirable that the particle size distribution of the particles are uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus, in which a plurality of color toner images are sequentially transferred from an image carrier to an intermediate transfer member, and then collectively transferred from the intermediate transfer member to a transfer material. The present invention relates to an image forming apparatus that performs simultaneous transfer and fixing.

[0002]

2. Description of the Related Art Conventionally, there are the following techniques for transferring a multicolor toner image using an intermediate transfer member.

(1) Japanese Patent Publication No. 49-209 discloses a technique in which electrostatic transfer is performed in primary transfer and pressure transfer is performed in secondary transfer. This is to improve the drawback of so-called color misregistration, in which, when multicolor printing is performed on a stretchable flexible material such as cloth or paper, images are shifted when overlapping and transferring each color. That is, the purpose and effect of the present invention is to reduce the color misregistration by transferring each color image intermediately to a blanket drum and transfer them all at once, thereby printing high-speed multicolor.

(2) Japanese Patent Application Laid-Open No. 50-23234 discloses that a secondary transfer section has a pressurizing / heating means.

That is, when the transfer step and the fixing step are separated, In the transfer process, paper dust or the like adversely affects the photosensitive drum. 2. Poor thermal efficiency during fixing. 3. The image is disturbed during transfer of the transfer material carrying the toner from the transfer section to the fixing section. This is an improvement over the above drawbacks.

It is another object of the present invention to transfer and fix a developed image formed on the surface of a photoreceptor to a transfer material while maintaining a clear image.

(3) Japanese Patent Application Laid-Open No. Sho 59-12576 discloses that primary transfer is performed by pressure and transfer is simultaneously fixed by secondary transfer. This is because it is difficult to perform registration when multiple transfer is performed on the same transfer material, and the transfer material has insufficient force to hold the transferred toner image, and the transfer material has to be transferred during the next transfer. Is improved in that the toner image is peeled off.

In this technique, since each toner image is transferred onto the intermediate transfer member, it is easy to adopt a transfer alignment system for each toner image onto the intermediate transfer member, and a high-quality image is always reproduced. It can be formed well on the next transfer material.

Further, since each toner image is transferred to the next transfer material after the transfer of the toner image to the intermediate transfer member, a margin for synchronization is particularly increased when the transfer material is transported, so that the transport mechanism can be simplified and reliability can be improved. The performance is also improved. Further, since the intermediate transfer member has a transfer layer (particularly, rubber type) capable of strongly holding the transferred toner image, the transfer characteristics are excellent.

The following are known techniques for simultaneous transfer and fixing.

(1) JP-A-49-78559 specifies the surface energy (adhesive force) hardness and calorific value of an intermediate transfer member.

(2) JP-A-57-23975 and JP-A-59-50473 disclose an intermediate transfer layer containing an addition polymerization type silicone rubber. The addition polymerization type silicone rubber has a small amount of unreacted portions and leached portions, so that contamination of the photosensitive layer is small, film strength and processability of the transfer layer are excellent, and good images are obtained.

(3) JP-A-59-139070 discloses that primary transfer is performed by electrostatic transfer and pressure fixing is performed by secondary transfer. The object is to provide an apparatus which can obtain a good copy image even in a plain paper copy using a low-resistance magnetic toner and in a humid condition and can be easily made compact.

(4) Japanese Patent Application Laid-Open No. 62-29327 discloses that an intermediate transfer member has a transfer layer of silicon rubber on a polyamide fiber woven fabric base material. here,
Polyamide fiber woven fabric is used as the base material of the intermediate transfer body, so it is flexible, and has good adhesion to the image carrier and the transfer material, so the transfer efficiency is improved. Has good adhesion and is easy to make into an endless belt.

As described above, many examples of the intermediate transfer member in the case of a multicolor toner image and examples of the simultaneous transfer fixing have been proposed.

In an example often seen in the case of a single-color image forming means, an intermediate transfer member having adhesiveness and release properties is used,
There is a method in which a toner image on a photosensitive drum is temporarily transferred by adhesion onto an intermediate transfer member and then fused and fixed from the intermediate transfer member onto a transfer material. In the primary transfer section, which is an adhesive transfer, an intermediate transfer member made of silicon rubber and a photosensitive drum are pressed against each other, and a toner image is adhered on the intermediate transfer member by adhesion. Next, in the secondary transfer section for fusion transfer, the heat roller and the intermediate transfer member are pressed against each other, and the toner image is heated and melted by the heat roller via the transfer material. The melted toner permeates into the fibers of the transfer material by pressure. At the same time, the intermediate transfer member is peeled off from the intermediate transfer member due to the releasability of the intermediate transfer member.

In the case of a multicolor image forming means, it is difficult to use adhesive transfer in the primary transfer section, and therefore, in many cases, electrostatic transfer is used. The simultaneous transfer fixing device has a relatively low electrostatic transfer efficiency of 80 to 90%,
It has been proposed to solve the problems such as the change in resistance and capacity due to the change in water content of the transfer material affecting the transfer efficiency and the scattering.

Further, as a device for preventing color misregistration and color unevenness in a conventional multicolor image forming apparatus using an intermediate transfer member, for example, as disclosed in Japanese Patent Laid-Open No. Some are designed to prevent meandering.

Further, US Pat. No. 4,65,651 discloses an example of using relatively inexpensive parts to maintain the high-precision resist control required for a full-color machine using color multiplexing.
Nos. 2,115 and 4,788,572, which use a method of synchronizing the photosensitive belt and the intermediate transfer belt.

As a multicolor image forming apparatus using such an intermediate transfer member, for example, a multi-transfer type copying apparatus is used to copy an original to a CC.
An image signal that has been read by a D-line sensor or the like and subjected to various processing, or an image signal directly output from a computer, is output to a laser driver, and the laser is driven to drive the laser. By performing the exposure, a latent image is formed on a photoreceptor uniformly charged in advance.

Next, after the latent image is developed by a toner in a developing device for the first color, the toner image is electrostatically transferred from the photosensitive member to the intermediate transfer member in a first transfer portion. A series of these steps are sequentially repeated by, for example, yellow, magenta, cyan, and black toners to form a full-color toner image on the intermediate transfer member. -After the image is collectively transferred from the intermediate transfer member to a transfer material (for example, paper), the image is conveyed into a fixing device and fixed, or is transferred and fixed at the same time, thereby completing the full color image forming sequence. The transfer material is discharged out of the apparatus, and the required full color image formation is completed.

When image formation is repeated, contaminants such as toner resin and external additives to the toner accumulate and fuse on the surface of such an intermediate transfer member with time, and these are indirectly exposed to light. Since it adheres to the body surface and affects the transfer efficiency, it is necessary to provide a cleaning means for the surface of the intermediate body, but this cleaning is also very difficult. The accumulation of these pollutants
It largely depends on the contact pressure between the photoreceptor and the intermediate in the primary transfer section or the secondary transfer section, and it is necessary to maintain a stable pressure or gap, but it is extremely difficult in terms of the apparatus configuration.

Further, when performing simultaneous transfer and fixing, a high releasable and heat-resistant material such as a fluororesin, a silicone resin or a rubber material is used on the surface of the intermediate transfer member.
A so-called offset, in which a part of the toner image melted by heat and pressure during the secondary transfer remains on the surface of the intermediate transfer member without being transferred and fixed on the transfer material, is more likely to occur than in a conventional fixing device.

In such a case, in the conventional fixing device, a release agent such as silicone oil is applied to the surface of the fixing roller in order to prevent the toner from being offset to the surface of the fixing roller. However, when such a release agent is applied to the surface of the intermediate transfer member, the release agent transfers to the surface of the photoreceptor via the intermediate transfer member.

The release agent thus transferred changes the surface condition of the surface of the photoreceptor. The charging potential becomes non-uniform, causing image unevenness. 2. This causes a decrease in transfer efficiency in the primary transfer. 3. A cleaning defect on the surface of the photoreceptor occurs. This can cause problems.

Therefore, an excessive release agent is supplied to the surface of the intermediate by using a capsule toner containing a polymer or a polymer solution as a release agent so that the toner itself has a release function at the time of fixing. There have been many proposals to achieve simultaneous transfer fixing. However, even in this configuration,
The polymer or the polymer solution, which is a release agent encapsulated in the toner, gradually accumulates on the surface of the intermediate and transfers to the surface of the photoreceptor, causing the above-described problem.

The inventor of the present invention also avoids direct contact between the surface of the photoreceptor and the surface of the intermediate member in the primary transfer portion, and has a space slightly larger than the thickness of the contaminant adhering to the surface of the intermediate member.
Providing a surface mount reduces contamination on the surface of the photoreceptor, is effective in offsetting to the surface of the intermediate body in a device that performs simultaneous transfer and fixing in the secondary transfer section, and furthermore, a polymer is used as a release agent. Alternatively, the present invention was found to be effective in preventing the release agent from adhering to the surface of the photoreceptor and the intermediate, which are generated when simultaneous transfer and fixing is performed using a capsule toner in which a polymer solution is sealed. It has been reached.

[0028]

SUMMARY OF THE INVENTION An object of the present invention is to minimize various problems such as a change in transfer efficiency with respect to surface contamination of an intermediate transfer member and a photosensitive member, and to maintain a stable image output. . Further, it is possible to solve the problem that occurs when simultaneous transfer and fixing is performed using a capsule toner in which a polymer or a polymer solution is sealed as a release agent, and to provide an image forming apparatus capable of outputting a stable image. is there.

[0029]

SUMMARY OF THE INVENTION The present invention provides an image having a primary transfer portion for transferring a toner image formed on an image carrier to an intermediate transfer member, and a secondary transfer portion for transferring the toner image from the intermediate transfer member to a transfer material. The image forming apparatus is characterized in that at least the primary transfer section has an image forming apparatus in which spacer particles are interposed between the photosensitive member and the intermediate transfer member to form a minute gap.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described as an example of application to an apparatus for simultaneously transferring and fixing a toner image on an intermediate transfer member to a transfer material in a secondary transfer portion.

FIG. 4 is a block diagram showing an embodiment of a full-color image forming apparatus to which the present invention is applied. The photosensitive drum 1 serving as an image carrier is made of a photosensitive member such as OPC or a-Si, and a peripheral portion thereof is irradiated with a pre-exposure lamp 7, a corona charger 2, and a laser beam corresponding to each color signal. An exposure unit including a scanner 3, a mirror-4, and the like; a rotary developing device 5 having four developing devices for accommodating yellow, magenta, cyan, and black toners, respectively; The cleaning unit 6 and the like are arranged. A pressure roller 9 is provided above the intermediate transfer member 8 so as to be able to contact and separate therefrom.

The sequence of the entire image forming apparatus having the above configuration will be briefly described. The reader R reads the original O illuminated by the halogen lamp 202 by the contact type CCD line sensor 201, converts this image signal into an electric signal, and outputs it to the printer unit D. The image size of the document O is also detected at the same time.

An image signal from the CCD 201 is input to an analog processing section, and the signal of the CCD 201 is sequentially output for each pixel in the order of cyan (C), green (G), and yellow (Y). Therefore, first, each color of C, G, and Y is separated.

Next, the developing devices 5Y, 5Y, 5
M, 5C and 5Bk are yellow (Y), magenta (M),
First, the image signal is converted to cyan (C).
The signals are converted into red (R), green (G), and blue (B) signals.

This is performed by arithmetic processing according to the equations of CG = B and YG = R. Further, the output signals of the signals separated into R, G, and B linearly change with respect to the density, and thus are converted into 8-bit density signals by the A / D converter.

The digitized image signal for each color is input to the gradation control circuit of the printer unit D through various processes.

In the gradation control circuit, image data is input to an address of a look-up table RAM (LUT RAM) so as to correspond to the color reproduction density of the printer unit D, and the data corresponding to this is inputted. Output data. This data is converted into an analog signal, pulse width modulated by a binarization circuit, output to a laser driver as an image signal, and drives the laser.

When the photosensitive drum 1 rotates in the direction of the arrow and is uniformly charged by the corona charger 2, image exposure is performed by the laser light E pulse-width modulated according to the yellow image signal of the document.

The electrostatic latent image of this yellow image is transferred to the yellow image which has been fixed at the developing position in advance by the rotation of the rotary developing device 5.
The image is developed by the developing device 5Y. At this time, the developing bias applied to the developing sleeve of the yellow developing device 5Y is a bias in which VDC = 400 V is superimposed on a rectangular wave alternating voltage having an alternating voltage value Vpp of 2 KV and a frequency f of 2 KHz.

The toner in the developing device consumed by the development is supplied from a toner hopper 51.

This yellow image is electrostatically transferred onto the film 80 of the intermediate transfer member 8 at the primary transfer portion X where the photosensitive drum 1 and the intermediate transfer member 8 are in contact with each other. Here, the film 80 of the intermediate transfer body 8 is rotating in the direction of the arrow in synchronization with the photosensitive drum 1, and continues to rotate while holding the yellow toner image on the surface, and the next color (FIG. Prepares for magenta) transfer.

On the other hand, the surface of the photosensitive drum 1 is cleaned by the cleaning unit 6 and then uniformly charged again by the corona charger 2, and is subjected to image exposure in accordance with the next magenta image signal.

The rotary developing device 5 rotates while an electrostatic latent image is formed on the photosensitive drum 1 in accordance with the magenta image signal by the above-described image exposure, and causes the magenta developing device 5M to be stationary at the developing position. A predetermined magenta development is performed, and the image is transferred onto the film 80 at the primary transfer section X.

Subsequently, the above-described process is also performed for the cyan and black colors, respectively, so that the transfer of the four colors to the intermediate transfer member is completed or the black in the final color is being transferred, The paper P serving as a transfer material accommodated in the printer is supplied by a paper supply roller 101.
The paper P is supplied to the registration rollers 102 and 103, the paper feed guide 1
Then, the sheet P is conveyed to the secondary transfer section Y of the intermediate transfer body via the printer 04 so as to match the four-color field toner image on the intermediate transfer body which is previously equivalent to the size of the paper P.

In this manner, the four-color toner-visible images formed on the intermediate transfer member are heated by the heating member 8 provided in the intermediate transfer member 8.
3 is transferred and fixed on the paper by the heat of 3 and the pressure of the pressure roller 9 which is brought into contact with the conveyance of the paper P, and is discharged onto the discharge tray 107 through the discharge rollers 105 and 106. Then, the full color image formation on the paper is completed.

Thereafter, the toner resin remaining on the surface of the heat-resistant sheet 80 of the intermediate transfer member is brought into contact with intermediate cleaning means 84 such as a felt pad containing silicone oil as a release agent. In addition to the cleaning, a release agent is applied, and thereafter, an appropriate amount of the spacer particles p is supplied by the spacer particle supply means 85 to prepare for the next step.

The operation of the intermediate transfer member 8 of this embodiment used in the image forming apparatus will be described with reference to FIGS. FIG. 1 is an enlarged view of the intermediate transfer body 8 in the present embodiment, FIG. 2 is an enlarged perspective view, and FIG. 3 is an enlarged view of a primary transfer unit.

The intermediate transfer member 8 is stretched around a driving roller 81 also serving as a transfer roller, a driven roller 82 also serving as a film tension roller, and a heating member (thermo heater) 83. Endless belt type thin film heat resistant film 80 is provided. The driving roller 81, the driven roller 82, the heating member 83, the pressure roller 9, the intermediate member cleaning means 84, and the spacer particle supply means 85 are arranged with respect to the rotation axis of the photosensitive drum 1. Are arranged substantially in parallel.

The spacer particle supply means 85 includes a driven roller.
The spacer particles s are mechanically or electrostatically supplied to the surface of the film material 80 in a contact or non-contact manner against the rubber 82. Thereafter, the film 80 is conveyed to the primary transfer portion X by driving the film 80, and is sandwiched between the photoreceptor 1 and the intermediate transfer member 8 as shown in FIG.

As a result, the toner formed on the photosensitive member 1
It is possible to prevent the contaminant p adhered to the surface of the film 80 from adhering to the surface of the photoreceptor without substantially disturbing the image t.

The spacer particles s may be larger than the thickness of the contaminant p attached to the surface of the film 80. For example, the spacer particles s have an average particle diameter of 1 to 50 μm, preferably 3 to 20 μm, for example, nickel, Copper, aluminum, brass, iron, manganese, cobalt, tungsten, black
Alloys and compounds such as boron, boron nitride, titanium nitride,
Zirconium nitride, boron carbide, titanium carbide, zirconium carbide, tungsten carbide, silicon carbide, silicon oxide, titanium boride, zirconium boride, cerium oxide, iron oxide, chromium oxide, zirconium oxide, titanium oxide, alumina, silica, Metal salts of higher fatty acids such as molybdenum disulfide, tungsten disulfide, boron nitride, lead oxide, antimony oxide, strontium sulfate, aluminum sulfate, calcium carbonate, strontium titanate, strontium oxide, zinc stearate, graphite, barium fluoride, Known inorganic or organic particles such as calcium fluoride, carbon fluoride, carbon black, conductive tin oxide, silicone resin, polytetrafluoroethylene powder, polyvinylidene fluoride powder, and toner binder. Used as Olefin resins such as polyethylene and polypropylene, polymethacrylic acid esters, methacrylic acid copolymers, acrylic resins such as acrylic acid copolymers, styrene copolymers such as styrene-acrylic acid copolymers, ethylene-vinyl acetate Copolymer,
Various vinyl resins such as polyvinyl chloride, polyamide resins such as polymerized fat-modified polyamide, alkyd resins such as phthalic acid resin and maleic acid resin, synthetic resins such as epoxy resin and phenol formaldehyde resin, and polyester resins And particles of one or more of various resins such as It is desirable that these particles have a uniform particle size distribution.

In the present invention, among these particles,
In particular, by using particles of a styrene-acrylic copolymer or polyester resin of the same type as the toner binder, a stable effect as spacer particles is exhibited, and at the time of simultaneous transfer fixing in the secondary transfer portion. In addition, since the fixing to the paper P as the transfer material was facilitated, the residue of the spacer particles s was reduced, and the addition to the intermediate cleaning means 84 could be reduced.

The spacer particles s are electrostatically or mechanically supplied to the surface of the film 80 by a spacer particle supply means 85 having a general fur brush, magnetic brush, elastic roller, or the like. You. The supply amount is, for example, a spacer particle s having an average particle diameter of 5 μm in order to reduce disturbance of the toner image t formed on the photoreceptor 1 as much as possible.
Is used, it is desirable to make it 40,000 / cm ² or less. The supply amount of the spacer particles s to the surface of the film 80 is Luzex-F (trade name) manufactured by NIRECO.
Was measured.

The spacer particles s are supplied to the surface of the film 80 before the primary transfer of the toner image t formed on the photoreceptor 1 to the surface of the film 80, that is, the intermediate cleaning means 84. It is desirable that they come and go at approximately the same timing as the operation of.

Both ends of the driving roller 81 and the driven roller 82 are rotatably supported between bearing members (not shown), and the heating element 83 is fixedly supported on an immovable member (not shown). However, instead of using the driving roller 81 as the transfer roller, the driven roller 82 is used as the transfer roller.
It can also be la.

The driving roller 81 is driven to rotate clockwise in the drawing by a driving system (not shown).
In the reference numeral 0, the conveying force is applied by the frictional force between the outer peripheral surface of the driving roller 81 and the inner surface of the film, and the inner surface of the film slides on the heating surface of the heating element 83 while the driving roller 81, the driven roller 82 and the heating roller 81 are heated. The transfer speed of the transfer paper P as the material to be heated (5 in this embodiment) is shown in FIG.
0 mm / sec).

Since the driving roller 81 of this embodiment is also used as a transfer roller, a core made of a conductive rigid material such as metal is used to add polyurethane, EPDM (ethylene propylene dimethyl rubber), polyisoprene, butadiene. Styrene copolymer, polybutadiene, isobutylene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-propylene copolymer, chlorosulfonated polyethylene, acrylate copolymer, organic polysiloxane, perfluoropropene, fluorine Conductive particles such as carbon are dispersed in a rubber elastic member such as a vinylidene fluoride copolymer, and the volume resistance RV is 10 ⁵ to 10 ¹⁰ Ωcm, and the
It is composed of an elastic layer formed of, for example, a foamable or rubber elastic body, having a C hardness adjusted to 10 to 65 degrees, preferably about 20 to 50 degrees.

The drive roller 81 in this embodiment places importance on the drive conveyance and heat resistance of the film drive belt 86,
Conductive particles are dispersed in a heat-resistant rubber elastic material such as silicone rubber or the like, and the volumetric resistance is 10 ⁷ to 10 ⁹ Ωcm, the Asker C hardness is 40 to 50 degrees, the outer diameter is 30 mm, and the thickness of the silicone rubber is 5 mm. And layers.

The contact pressure of the drive roller 81 with the photosensitive drum 1 is 10 gf to 2 kgf, preferably 0.3 gf to 1 kgf, with the film 80 and the film drive belt 86 being sandwiched therebetween. It is pressed.

A bias of 1-2 KV is applied from a transfer bias power supply 86 to a core of the drive roller 81 as the transfer roller. This bias is sequentially increased according to the order of lamination of the toner, and is 1 KV for the first color and 1.5 KV for the second color.
KV, 2 KV for the third color, and 2.5 KV for the fourth color. When only a single color is used, the voltage is 1 KV as in the case of the first color. These transfer biases are controlled by a constant voltage or a constant current. In this embodiment, the transfer bias is only DC, but an AC component can be superimposed.

The heating element 83 includes a heater substrate 83a,
A heating element layer 83b formed in a narrow band or linear shape along the longitudinal direction at a substantially central portion of the upper surface of the substrate, and a surface protection layer covering the upper surface of the substrate including the heating element layer 83b with a thickness of about 10 μm. , A heat detecting element 83d provided on the lower surface of the substrate 83a, and a heater support 83e for thermally insulating the substrate.

The heater substrate 83a is a member having heat resistance, insulation, and low heat capacity. As an example, the thickness is 1 mm and the width is 5 to 5.
An alumina substrate having a length of 10 mm and a length of 330 mm can be used.

The heating element layer 83b is formed by screen printing or the like made of an electric resistance material such as Ag / Pd (silver palladium) / Ta2N and having a thickness of 10 μm, a width of 1 to 3 mm and a length of 310 mm. Layer.

The temperature measuring element 83d is, for example, a low-heat-capacity temperature-measuring resistor such as a Pt film coated on the lower surface of the substrate by screen printing or the like, and a silicone-based adhesive having good thermal conductivity is attached to a substantially central portion of the lower surface of the substrate. This is a low heat capacity NTC thermistor bonded with an agent or the like.

The heater support 83e supports the above-mentioned heating element components 83a to 83d insulated from the whole of the fixing device and the copying machine, and has heat insulation, high heat resistance and rigidity, for example, polyphenylene sulfide. And high-heat-resistant resins such as polyamideimide, polyimide, polyetheretherketone, and liquid crystal polymer, and composite materials of these resins with ceramics, metal, glass and the like.

When electricity is supplied to the heating element layer 83b, heat is generated and the heater substrate 83a is heated. This heater substrate 83a
Is fed back to a control circuit (not shown) by controlling the power supply to the heating element layer 83b, and the temperature of the heating element 83 is controlled to a predetermined fixing temperature (180 ° C.). You.

The temperature control of these heating members is controlled so that the paper P serving as a transfer material has a predetermined temperature immediately before passing through the secondary transfer portion Y. To prevent

Here, the energization is performed, for example, by applying a pulse having a pulse shape corresponding to a desired temperature and energy release amount controlled by the temperature detecting element 83d with a pulse shape having a DC 20 V cycle of 20 ms. Generally, the pulse width is 0.5 to 5 ms. Or AC100V
Then, the energized power is controlled by controlling the phase angle of energization by an energization control circuit (not shown) including a triac according to the heater substrate temperature detected by the temperature detecting element 83d.

The heating element 83 has a small heat capacity of the heater substrate 83a, the heating element layer 83b, the surface protection layer 83c, and the temperature detecting element 83d, and is insulated by the support 83e. The temperature of the heater substrate 83a reaches the temperature at which the toner layer on the film 80 and the transfer paper P can be fixed in a short time (quick start property), and the heating element 83 is heated.
There is no need for standby temperature control to preheat electricity
Energy saving can be realized, and the temperature rise in the apparatus such as the intermediate transfer body 8 and the photosensitive drum 1 around the intermediate transfer body 8 can be prevented.

When the temperature of the heater substrate 83a is
The temperature is detected by d, and the temperature is fed back to a control circuit (not shown), and the power supply to the heating element layer 83b is controlled so that the temperature of the heating element 83 is controlled to a predetermined fixing temperature (180 ° C.).

The intermediate cleaning means 84 is provided with a cleaning means such as a felt pad or a web so as to contact the outer surface of the film 80.

The felt pad contains a release agent such as silicone oil, and the surface of the film 80 is cleaned and applied with the release agent by contact with the film 80.

However, as for the toner produced by the pulverization method, as described above, the felt pad needs to contain an oil containing a release agent such as a silicone oil, which is proposed in, for example, Japanese Patent Publication No. 36-10231. A polymer or polymer solution having a mold release agent enclosed therein, which is produced by a polymerization method such as suspension polymerization, emulsion polymerization, precipitation polymerization, dispersion polymerization, so-free emulsion polymerization, or seed polymerization. When an encapsulated capsule toner is used, the toner does not need to be applied to the film 80 because the toner contains the release agent.

The pressure roller 9 is, like the pressure roller in a general fixing device, provided on a heat-resistant rubber elastic body such as silicone rubber, and provided with a highly releasable skin such as PFA or PTFE. A layer is formed, and this is brought into contact with and separated from the heating surface of the heating element 83 by pressing the film 80.

The contact / separation timing may be set after the toner image of the fourth color (here, black and the final color) is formed on the film material 80 in the primary transfer portion X, immediately before passing through the secondary transfer portion Y, or Paper P, which is a transfer material, is fed by a paper feed roller 101, and a registration roller 102, 10
3. Immediately before being conveyed to the secondary transfer portion Y of the intermediate transfer body via the paper feed guide 104, the heating is performed by pressing the film material 80 with a contact force of 2 to 20 kgf, preferably 4 to 8 kgf. The film 8 is pressed against the upper surface of the
With the rotation of 0, the film rotates in the forward direction with the rotation direction of the film at substantially the same speed as the film speed.

Next, the film 80 will be described with reference to FIG. The film 80 is a base layer (base film) 80a.
And a high release layer 80b having a heat resistance of, for example, 5 μm thickness.
It is composed of The base layer 80a is made of a heat-resistant resin such as polyester, PET (polyethylene terephthalate),
High heat-resistant resins such as PFA (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer), PTFE (polytetrafluoroethylene), polyethylene sulfide, polyamideimide, polyimide, polyetheretheroketone, liquid crystal polymer, etc. Or a metal sheet of aluminum, nickel, or the like, or a composite material of these with ceramics, metal, glass, or the like.

For the high release layer 80b, for example, the same fluororesin or fluororubber such as PET, PFA, PTFE, or the like as the above-mentioned base layer, silicone resin, or silicone rubber is used.

Further, a more preferable structure of the film is that these heat-resistant sheets have a low-resistance layer, and have a volume resistance RV equivalent to that of the driving roller 81 and the film driving belt 86 to 10 ⁵ to 10. ¹⁰ Ωcm.

The film 80 has an endless structure.
Perimeter 40mm, width 320mm, total thickness 100μ
m, preferably 40 μm or less. In this embodiment, as the base layer (base film) 80 a of the film 80, a polyimide film having a thickness of 20 μm, a high release layer 80 b
As a 5 μm-thick P
The FA layer is applied. Since the film 80 having this configuration is particularly excellent in the releasability, the transfer efficiency to the transfer material in the secondary transfer is close to 100%.

As an embodiment of the present invention, an apparatus for performing simultaneous transfer and fixing in a secondary transfer section has been described. However, in the secondary transfer as shown in the conventional example, only transfer onto a transfer material is performed.
It is also effective for an apparatus configuration in which fixing is performed by a separately provided fixing device.

Similarly, the photoreceptor has been described as having a drum shape. However, the photoreceptor may have a drum shape or a belt shape, and the same applies to an intermediate transfer member. Not done.

Further, although a system using a semiconductor laser has been described as a latent image forming means, the present invention is not limited to this, and a digital latent image forming means such as an LED, a liquid crystal, an ionography, etc. It is also effective in an analog latent image forming means for directly forming an image signal directly on a photoreceptor without using an image reading means as described above.

Although the full-color image forming apparatus having a four-color developing system has been described as an embodiment of the present invention, it goes without saying that the present invention can be applied to a single-color or plural-color image forming apparatus.

[0084]

【Example】

Example 1 In this example, a colorless polyester resin powder having an average particle diameter of 15 μm manufactured by a conventionally known pulverizing method was used as the spacer particles s.

The spacer particles s are carried by spacer supply means 85 and applied to the surface of the film 80 by mechanical rubbing so as to have a density of about 2000 particles / cm ² .

In this embodiment, the developer has an average particle diameter of 50.
So-called two-component development in which toner particles of four colors of yellow, magenta, cyan and black, each having a binder of a polyester resin having an average particle size of 8 μm, are mixed with carrier particles obtained by resin coating ferrite powder having a particle size of μm. Agent was used.

The present embodiment will be described below as an example of application to an apparatus for simultaneously transferring and fixing a toner image on an intermediate transfer member to a transfer material in a secondary transfer portion in FIG.

The photosensitive drum 1 serving as an image carrier is composed of an OPC photosensitive drum, around which a pre-exposure lamp 7,
An exposure unit including a corona charger 2, a laser scanner 3 for irradiating laser light corresponding to each color signal, a mirror-4, and the like, and yellow, magenta, cyan, and black toners, respectively. Rotary developing device 5 having four developing devices to accommodate
, An intermediate transfer member 8, a cleaning unit 6, and the like. A pressure roller 9 is provided above the intermediate transfer member 8.
Are arranged so that they can come and go.

The sequence of the entire image forming apparatus having the above configuration has been described in the above-described embodiment of the present invention and will not be described.

The yellow image developed on the photosensitive drum 1 in this manner is transferred onto the film 80 of the intermediate transfer member 8 at the primary transfer portion X where the photosensitive drum 1 contacts the intermediate transfer member 8. It is transferred electrostatically.

Here, the gap between the primary transfer portion X where the photosensitive drum 1 and the film 80 are in contact with each other becomes equal to the particle size of the spacer particles s by sandwiching the spacer particles s.

As described above, the surface of the film 80 is coated with silicone oil as a release agent in advance, but since the spacer particles s are supplied on the silicone oil film, the surface of the film 80 The silicone oil film comes into non-contact with the surface of the photosensitive drum 1, and the transfer of the silicone oil to the surface of the photosensitive drum 1 can be prevented.

Thus, the film 80 of the intermediate transfer member 8 is
It rotates in the direction of the arrow in synchronization with the photosensitive drum 1 and continues to rotate while holding the yellow toner image on the surface, preparing for the transfer of the next color (magenta in FIG. 4).

On the other hand, the surface of the photosensitive drum 1 is cleaned by the cleaning unit 6 and then uniformly charged again by the corona charger 2, and is subjected to image exposure in accordance with the next magenta image signal.

The rotary developing device 5 rotates while an electrostatic latent image is formed on the photosensitive drum 1 in accordance with the magenta image signal by the above-described image exposure, and fixes the magenta developing unit 5M at the developing position. A predetermined magenta development is performed, and the image is transferred onto the film 80 at the primary transfer section X.

In this case, as described above, the transfer of silicone oil to the photosensitive drum 1 could be prevented.

Subsequently, the above-described process is also performed for the cyan and black colors, respectively, so that the transfer of the four colors to the intermediate transfer member is completed or the transfer of the final color black is completed. The paper P serving as a transfer material accommodated in the printer is supplied by a paper supply roller 101.
The paper P is supplied to the registration rollers 102 and 103, the paper feed guide 1
Then, the sheet P is conveyed to the secondary transfer portion Y of the intermediate transfer member via the printer 04 so as to match the toner image of four colors on the intermediate transfer member which is previously equivalent to the size of the paper P.

In this manner, the four-color toner-visible images formed on the intermediate transfer member are heated by the heating member 8 arranged in the intermediate transfer member 8.
3 is transferred and fixed on the paper by the heat of 3 and the pressure of the pressure roller 9 which is brought into contact with the conveyance of the paper P, and is discharged onto the discharge tray 107 through the discharge rollers 105 and 106. Then, the full color image formation on the paper is completed.

Thereafter, the toner resin remaining on the heat-resistant sheet surface of the intermediate transfer member is brought into contact with an intermediate cleaning unit 84 such as a felt pad containing silicone oil as a release agent. And a silicone oil is applied. Thereafter, an appropriate amount of the spacer particles p is supplied by the spacer particle supply means 85 to prepare for the next step.

A modified LBP2030 machine manufactured by Canon Inc. equipped with the configuration of the present embodiment as described above
When a full color copy was performed, no problem occurred.

As described above, in the present configuration, in the image forming apparatus using the intermediate transfer member, accumulation of various contaminants such as silicone oil on the surface of the photosensitive drum or the surface of the intermediate transfer member, and image defects due to fusion. Can be prevented, and stable image output can be performed over a long period of time.

Comparative Example 1 Full color copying was performed by stopping the supply of the spacer particles s from the apparatus described in Example 1, but an image defect considered to be a cleaning defect occurred from about 40 sheets. did. Observation of the surface of the photoreceptor drum revealed that a cleaning defect occurred due to the adhesion of silicone oil, and that toner was fused on the drum surface of the photoreceptor drum.

Example 2 In this example, a colorless spherical silicone resin having an average particle diameter of 10 μm (Tospar, manufactured by Toshiba Silicone Corporation) was used as the spacer particles s. .

The spacer particles s were carried by a spacer supply means 85 and applied to the surface of the film 80 at a rate of about 1000 particles / cm ² .

Also, in Example 1, the effect of the present invention on toner produced by the pulverization method has been described. In this example, however, the toner produced by the suspension polymerization method was used.
The case where a polymer or a polymer solution-encapsulated capsule toner in which a release agent is encapsulated is used will be described.

In this embodiment, the device construction and the like are substantially the same as those in Embodiment 1. However, since the toner used in this embodiment is sealed with a release agent, the intermediate cleaning means 84 is used.
The felt pad does not necessarily contain a release agent such as silicone oil.

Next, a method for producing a capsule toner in which a polymer or a polymer solution is sealed as a release agent used in the present embodiment will be described. (Production Example of Polymerized Toner) Styrene: 185 parts Trifluoroethyl acrylate: 15 parts Cyclic rubber [Albex CK-450 (manufactured by Hoechst Japan)]: 10 parts Cyanimble-4920 (manufactured by Dainichi Seika Co., Ltd.) ): 20 parts Paraffin wax T-550 (manufactured by Nippon Seiro Co., Ltd.): 32 parts Initiator [V-601 (manufactured by Wako Pure Chemical Industries, Ltd.)]: 10 parts The above formulation is heated to 70 ° C. in a container. , Dissolved or dispersed to prepare a monomer system.

Separately, 10 g of aminoalkyl-modified colloidal silica was added to 1200 ml of ion-exchanged water, and HCl was added.
PH was adjusted to 6 with 1 g of Na ₂ CO ₃ ,
The mixture was heated to ℃ and dispersed with a TK homomixer type M (manufactured by Tokushu Kika Kogyo KK) at 10,000 rpm for 15 minutes.

Further, 1.1 g of Al ₂ (SO ₄ ) ₃ was added,
The mixture was dispersed at 10,000 rpm for 15 minutes, the dispersion medium was adjusted, the above monomer composition was charged, and the mixture was charged to 60 ° C. at 10,000 rpm using a TK homomixer at 70 ° C. under a nitrogen atmosphere.
The mixture was stirred for minutes, and the monomer composition was granulated.

Thereafter, the mixture was stirred at 70 ° C. while stirring with a paddle stirring blade.
Polymerization took place in 10 minutes. After the completion of the polymerization reaction, the reaction product was cooled, NaOH was added to dissolve the dispersant, and the polymer was filtered, washed with water and dried to obtain a polymer as a paraffin wax or a capsule toner encapsulating the polymer solution. Obtained.

Various external additives were added to the toner similarly to the toner produced by the pulverizing method of Example 1, and mixed with a carrier to obtain a two-component developer.

In this example, carrier particles obtained by resin coating ferrite powder having an average particle size of 40 μm were added to yellow, magenta, and magenta particles having an average particle size of 6 μm.
A so-called two-component developer in which four color toners of cyan and black were mixed was used.

The LB manufactured by Canon Inc. described in Example 1
2000 full color copies with P2030 remodeling machine
As a result, no problem occurred in this embodiment.

As described above, even when the polymer or the encapsulated toner in which the polymer solution is sealed is used as the release agent, the contamination of the surface of the intermediate transfer member and the photosensitive drum of the release agent is caused by the release agent. For example, various problems such as a change in transfer efficiency were suppressed as much as possible, and a stable image output could be maintained.

Comparative Example 2 Full color copying was performed by stopping the supply of the spacer particles s from the apparatus described in Example 1, but an image defect considered to be a cleaning defect occurred from about 200 sheets. did.
Then, when observing on the photoreceptor drum, an adhering substance which was seen as paraffin wax was observed,
The toner was fused on the surface of the photosensitive drum.

Embodiment 3 In the above embodiment, the spacer particles are supplied by arranging the spacer particle supplying means 85 near the intermediate transfer member. However, in this embodiment, the spacer particles are supplied. The supply of the spacer particles to the primary transfer portion is performed from a developing device.

A spacer particle is externally added to at least one of the developing devices 5Y, 5M, 5C, and 5Bk, and the spacer particle is exposed at a timing other than when an image is formed on the photosensitive drum 1. By developing the toner on the body drum and indirectly transferring the spacer particles to the surface of the intermediate transfer member 8, the same effect as in Example 1 or 2 was obtained.

FIG. 6 is a block diagram showing one embodiment of a full-color image forming apparatus to which the present invention is applied.
A configuration in which spacer particles are externally added to the developers included in Y, 5M, 5C, and 5Bk will be described.

When the photosensitive drum 1 rotates in the direction of the arrow and is uniformly charged by the corona charger 2, first, the yellow developing unit 5Y previously set at the developing position by the rotation of the rotary developing device 5 causes the photosensitive drum 1 to rotate. A bias is applied so that only the spacer particles are developed.

In this example, a negatively charged toner having an average particle diameter of 7 μm was used, and spacer particles which were to be positively charged were selected. Strontium titanate having an average particle diameter of 12 μm was used for the toner. 2% is externally added.

During development in the developing devices 5Y, 5M, 5C, and 5Bk in the above-described image forming process, an appropriate amount is set so as to be about 1500 / cm ² especially in the non-image area on the photosensitive drum 1. Spacer particle replenishment is performed.

The spacer particles thus developed on the photosensitive drum are conveyed to the primary transfer section as the photosensitive drum 1 rotates.

When 2000 full-color copies were made using the modified LBP2030 manufactured by Canon Inc. described in Example 1 with such a configuration, no problem occurred in this example.

As described above, this configuration can also prevent the accumulation of various contaminants on the surface of the photosensitive drum or the surface of the intermediate transfer member in the image forming apparatus using the intermediate transfer member, and prevent image defects due to fusion. It is possible to output images stably for a long period of time.

Embodiment 4 In this embodiment, as shown in FIG. 7, which shows an embodiment of the image forming apparatus of the present invention, the primary part is located downstream of the opposing portion of the photosensitive drum 1 and the rotary developing device 5. The structure is such that spacer particle supply means 85 is provided at a position upstream of the transfer section X.

Here, the spacer supply means 85 used in this embodiment will be described with reference to FIG. Spacer
The supply means 85 includes a container 85 containing the spacer particles s.
0 and a photosensitive particle drum 1 and a spacer particle carrier 851 composed of an aluminum cylinder carrying a spacer particle s on the surface thereof.

In this example, a spherical polyester resin having an average particle size of 15 μm was used as the spacer particles s. The spacer particle s is a spacer particle carrier 851
Is coated in a thin layer by a conventionally known blade coating means, and is electrostatically applied onto the photosensitive drum 1 by a bias applied between the photosensitive drum 1 and the spacer particle carrier 851. Transferred.

Here, the spacer particle carrier 851 has:
A DC bias of −600 V is applied to the photosensitive drum 1
On the upper side, about 1000 particles / cm ² are supplied.

The spacer particles s are conveyed to the primary transfer section X by the rotation of the photosensitive drum 1 and transferred to the film 80.

It is preferable that the step of applying the spacer particles s be performed before the formation of the latent image on the photosensitive drum 1. However, each latent image formed on the photosensitive drum 1 is separated from the developing device 5Y, 5M,
After development by 5C and 5Bk, spacer particles may be transferred to the surface of the photosensitive drum 1.

When 2000 full color copies were made using the modified LBP2030 manufactured by Canon Inc. described in Embodiment 1 with such a configuration, no problem occurred in this embodiment.

As described above, this configuration can also prevent the accumulation of various contaminants on the surface of the photosensitive drum or the surface of the intermediate transfer member in the image forming apparatus using the intermediate transfer member, and prevent image defects due to fusion. It is possible to output images stably for a long period of time.

[0133]

The image forming apparatus of the present invention has an image having a primary transfer portion for transferring a toner image formed on an image carrier to an intermediate transfer member and a secondary transfer portion for transferring the toner image from the intermediate transfer member to a transfer material. In the forming apparatus, spacer particles are interposed at least between the image carrier in the primary transfer section and the intermediate transfer body to form minute gaps, thereby accumulating various contaminants on the surface of the photoconductor or the intermediate transfer body. This has the remarkable effect that image defects due to fusion can be prevented and stable image output can be performed over a long period of time.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of an intermediate transfer member used in an image forming apparatus of the present invention.

FIG. 2 is an enlarged perspective view of an intermediate transfer member used in the image forming apparatus of the present invention.

FIG. 3 is an enlarged cross-sectional view of a primary transfer section of an intermediate transfer member used in the image forming apparatus of the present invention.

FIG. 4 is a schematic configuration diagram showing an embodiment of the image forming apparatus of the present invention.

FIG. 5 is an enlarged view of a film used for an intermediate transfer member used in the image forming apparatus of the present invention.

FIG. 6 is a schematic configuration diagram showing another embodiment of the image forming apparatus of the present invention.

FIG. 7 is a schematic configuration diagram showing another embodiment of the image forming apparatus of the present invention.

FIG. 8 is an explanatory diagram of a spacer particle supply unit shown in a schematic configuration diagram showing another embodiment of the image forming apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum (image carrier) 2 corona charger 3 laser scanner 4 mirror 5 rotary developing device 5Y yellow developing device 5M magenta developing device 5C cyan developing device 5Bk black developing device 51 toner hopper 6 cleaning Unit 7 Pre-exposure lamp 8 Intermediate transfer member 80 Film 80a Base layer (base film) 80b High release layer 81 Drive roller 82 Follower roller 83 Heater (thermal heater) 83a Heater Substrate 83b Heating element layer 83c Heat resistant glass 83d Temperature sensor 83e Heater support 84 Intermediate cleaning means 85 Spacer particle supply means 850 Container 851 Spacer particle carrier 86 Film drive belt 9 Pressure roller 100 Paper supply unit 101 Paper supply roller 102 Registration roller 103 Registration roller 104 Paper supply guide 105 Discharge Roller 106 Discharge Roller 107 Discharge Tray 201 CCD Line Sensor or CCD 202 Halogen Lamp D Printer E Laser Light O Original P Paper R Leader X Primary Transfer Part Y Secondary Transfer Part s spacer particle t toner image p spacer particle

Claims (1)

[Claims] 1. An image forming apparatus comprising: a primary transfer portion for transferring a toner image formed on an image carrier to an intermediate transfer member; and a secondary transfer portion for transferring the toner image from the intermediate transfer member to a transfer material.
An image forming apparatus characterized in that a spacer is interposed between a photosensitive member and an intermediate transfer member in at least a primary transfer section to form a minute gap.