JP2000292986A - Toner for forming color image, fixing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make similarly fixable toner images different from one another in color in a molten state and to make fixable a color image on a transfer material by direct exposure with a halogen heater or the like. SOLUTION: A styrene-butyl acrylate copolymer is used as a resin material used as the binder of each toner and the molecular weight of the resin is varied in accordance with the heat absorption efficiency of the pigment of each toner so as to provide, e.g. 90 deg.C, 150 deg.C, 160 deg.C and 190 deg.C softening temperature to yellow, magenta, cyan and black toners, respectively. The resulting toners can be simultaneously fixed in a uniform molten state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming and fixing a toner image on a transfer material by an electrophotographic method, a fixing device for fixing a toner image adhered on a transfer material, and a color image. The present invention relates to a color image forming toner used for formation.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a charging means, a writing means, and a developing means are provided on a peripheral portion of a rotating photoreceptor. The latent image of the image is formed by performing image exposure by the means, and the latent image is developed by the developing means to form a toner image on the surface of the photoreceptor. On the other hand, the transfer material fed from the transfer paper storage means is sent to a transfer position, where the toner image is transferred onto the transfer material at the transfer position. The transfer material to which the toner image adheres is heated when passing through the image fixing device, and the toner is fused onto the transfer material to be fixed, and then discharged onto a paper discharge tray.

In a double-sided image forming apparatus for forming an image on both sides of a transfer material, a surface image is formed on one surface (front surface) of the transfer material, and then the image is fixed.
The toner image of the back side image formed on the photoreceptor surface is transferred to the back side of the transfer material at the transfer position, passes through the image fixing device again to fix the back side image, and is discharged onto the paper discharge tray.

Further, in a color image forming apparatus for forming a color image on a transfer material, a plurality of, for example, yellow (Y), magenta (M), cyan (C), and black (K) are provided on a peripheral portion of a rotating photosensitive member. Developing means incorporating color toners of different colors are formed on the surface of the photoreceptor, and color toner images of respective colors of Y, M, C, and K are superimposed and then collectively transferred onto a transfer material at a transfer position. The transfer material carrying the toner image superimposed thereon passes through a fixing device, and the color image is fixed on the transfer material. In addition, as a color image forming apparatus for forming a color image on a transfer material, other than a method in which a plurality of color toner images are formed on the photoreceptor surface as described above and these are collectively transferred onto the transfer material, An image forming unit having a plurality of photoreceptors was provided, a single-color toner image was formed on the photoreceptor surface, transferred to a transfer material, and formed on the photoreceptor surface on a transfer material carrying the single-color toner image. There is also known a color image forming apparatus in which a color toner image on a transfer material is fixed after a toner image of another color is overlaid and transferred. In either system, the different color toner image adhered on the transfer material is heated and fused onto the transfer material when passing through the fixing device.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the following problems.

In a fixing device for fixing a color image transferred onto a transfer material by irradiation light of a halogen heater, all the toners of each color are used because the light absorption efficiency varies depending on the color of the toner fused on the transfer material. Cannot fix at proper temperature.

That is, when the toner is irradiated with an amount of light such that the yellow (Y) toner having low light absorption efficiency is heated to a temperature at which the toner is sufficiently fixed, the black (K) toner having high absorption efficiency is heated more than necessary. This can lead to smoke. On the other hand, if an amount of light is applied such that the black (K) toner is heated at an appropriate temperature, the fixing of the yellow (Y) toner becomes insufficient and the toners of all colors are fused and fixed at an appropriate temperature. Can not.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner for forming a color image, which can fix a toner image of a different color in the same manner as a fused state.

When a narrow transfer material is fed to a fixing device having a fixing roller using a halogen heater as a heat source and a toner image is fixed, both ends of the fixing roller immediately after that are not involved in heating the toner and the paper. For this reason, both ends are hotter than the central part, and both ends are too hot, and if a wide transfer material is subsequently fed, there will be inconveniences such as offset and shortening the life of the fixing roller. there were.

An object of the present invention is to provide a fixing device capable of reducing a temperature difference between an end portion and a center portion of a fixing roller by mainly heating the width of a transfer material.

In general, a fixing device is composed of a fixing roller having a heat source and a pressure roller having a rubber layer on the outer periphery that is in pressure contact with the fixing roller, and a fed toner image on a transfer material is fixed by heating the fixing roller. However, the toner image of the transparency (OHP paper) used for the OHP cannot obtain a smooth toner image only by press-contact heating of the fixing roller, and if the toner image is not sufficiently translucent, it is bright when projected on the OHP. A color projection image cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of fixing a toner image on an OHP sheet with improved translucency by utilizing a sheet reversing device.

In general, a fixing device includes a fixing roller having a heat source and an elastic pressure roller which presses against the fixing roller. A toner image on a transfer material to be fed is a nip formed by the fixing roller and the pressure roller. The fixing roller is heated and fixed in the fixing portion, but the passing time of the nip portion is short, so that the fixing roller needs to maintain a considerably high temperature, and power consumption is not small.

Conventionally, there has been proposed a method in which the nip portion is inclined with respect to the path of the transfer material, the path of the transfer material is bent by an entry guide, the transfer material is fed into the inclined nip portion, and the fixing roller is brought into contact before pressing. However, when the transfer material is thick paper, there is a problem that it is difficult to enter along the entry guide.

According to the present invention, by setting the toner image to be heated even when the transfer material is thick paper and outside the nip area, the heating time is lengthened to lower the set temperature to the fixing roller. The purpose of the present invention is to provide a fixing device that saves power consumption.

The width of the transfer material fed to the fixing device is not constant. Therefore, if the heat amount distribution in the axial direction of the fixing roller is set uniformly for a wide transfer material, the transfer material of the narrow transfer material is After the fixing, the temperature of the end of the fixing roller becomes excessively higher than that of the center, and the heat distribution becomes uneven.

An object of the present invention is to provide a fixing device capable of changing the axial heat distribution of a fixing roller according to the width of a transfer material to be fixed.

[0018]

SUMMARY OF THE INVENTION The present invention achieves the above-mentioned objects, and the first object is to form a color image by superimposing toner images of respective colors developed with a plurality of color toners. This is achieved by the color image forming toner (the invention according to claim 1), wherein the toners of the respective colors used have different softening temperatures depending on the type of the color.

A second object of the present invention is to provide a fixing device for fixing a toner image by heating a fixing roller containing a heater, wherein the fixing roller is provided with a variable angle reflecting member inside. (The invention according to claim 7).

A third object of the present invention is to provide an image forming apparatus provided with a fixing device comprising a fixing roller for heating and a pressing roller pressed against the fixing roller, wherein the pressing roller has an elastic layer on its outer periphery. Wherein the toner image is fused by heating the fixing roller, and then pressed and fixed by the elastic layer of the pressure roller, thereby achieving the image forming apparatus (the invention according to claim 11). .

The fourth object is to comprise a fixing roller for heating and a pressure roller for pressing against the fixing roller.
In a fixing device in which a transfer material is sandwiched and conveyed between the fixing roller and the pressure roller to fuse a toner image, one of the fixing roller and the pressure roller is positioned when the transfer material is sandwiched and conveyed. This is achieved by a fixing device characterized by being changed (the invention according to claim 14).

The fifth object is to comprise a fixing roller for heating and a pressure roller for pressing against the fixing roller,
In a fixing device that sandwiches and transfers a transfer material between the fixing roller and the pressure roller to fuse a toner image, the fixing roller includes a plurality of heat sources, and the plurality of heat sources are moved in a transfer direction of the transfer material. This is achieved by a fixing device (the invention according to claim 22), which is movable in the vertical direction.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the image forming apparatus of the present invention will be described. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms.

FIG. 1 is a sectional view of a color image forming apparatus showing an embodiment of an image forming apparatus having a process cartridge.

Belt photoconductor 10 as a belt-shaped image carrier
Is an endless flexible photosensitive belt stretched around a driving roller 1, a first rotating roller 2 and a second rotating roller 3 as a roller member. And the backup member 4 provided on the inner peripheral surface.
1 and 4b, while rotating in the clockwise direction indicated by the arrow in FIG. The belt photoreceptor 10 is provided with a thin metal film such as tin oxide, lead oxide, or indium oxide as a conductive layer on a flexible substrate such as polyester, polyimide, or polyethylene terephthalate.
C), and the conductive layer is grounded. The belt photoreceptor 10 used in the present embodiment has a base of 80 μm thick polyethylene terephthalate and is coated with OPC.
It is molded with high accuracy so as to have a uniform thickness of 100 μm.

The belt photoreceptor 10 is provided with a cleaning device 19 as a belt-shaped image carrier cleaning means described later.
And the waste toner collecting container 190 and the resin casing 140
And is configured as a process cartridge 300.

A scorotron charger 11 as a charging unit, an exposure optical system 12 as a scanning unit, and a developing unit 13 as a developing unit, which will be described below, are respectively yellow (Y), magenta (M), and cyan (C). And black (K)
Are used for the image forming process of each color, and in the present embodiment, the belt photoconductor 1
0, Y, M, C, and K are arranged in this order with respect to the rotation direction of the belt photoconductor 10 indicated by the arrow in FIG.

A scorotron charger 11 as a charging means for each color is opposed to and close to the belt photoreceptor 10 in a direction orthogonal to the moving direction of the belt photoreceptor 10 as an image forming body (a direction perpendicular to the paper of FIG. 1). A control grid (without a sign) maintained at a predetermined potential with respect to the aforementioned organic photosensitive layer of the belt photoreceptor 10 and a corona discharge electrode (without a sign), for example, a saw-tooth electrode, The charging action (minus charging in the present embodiment) is performed by corona discharge having the same polarity, and the belt photoconductor 10 is charged.
To give a uniform potential. As a corona discharge electrode,
In addition, a wire electrode or a needle electrode can be used.

Exposure optical system 12 as a scanning means for each color
Scans (exposes) a laser beam emitted by a semiconductor laser with a polygon mirror rotated by a drive motor, scans (exposes) scanning light (exposure light) on the belt photoreceptor 10 via an fθ lens, and forms a latent image. Perform formation. This scanning light is performed by subjecting image signals of respective colors read by a separate image reading device to image processing and inputting them to the exposure optical system 12 as electric signals.

The exposure optical system 12 for each color moves the scanning position on the belt photoconductor 10 between the scorotron charger 11 and the developing unit 13 by scanning the belt photoconductor 10 with scanning light. It is arranged outside the photoconductor 10 away from the photoconductor 10.

The developing device 13 as a developing means for each color includes
Inside yellow (Y), magenta (M), cyan (C)
Alternatively, a two-component (or one-component) developer of black (K) is accommodated, and the belt surface is arranged on one side of the vertically arranged belt photoconductor 10 at right angles to the moving direction of the belt photoconductor 10. It is arranged up and down so as to be positioned in parallel with the.

In the developing area, the belt is applied to the developing sleeve 131 by applying a DC voltage of the same polarity as the toner (minus polarity in the present embodiment) or a voltage that superimposes the AC voltage AC on the DC voltage as a developing bias. Non-contact reversal development is performed on the exposed portion of the photoconductor 10.

As described above, the developing device 13 transfers the electrostatic latent image formed on the belt photoreceptor 10 by the charging by the scorotron charger 11 and the scanning light by the exposure optical system 12 to the belt photoreceptor in a non-contact state. The reversal development is performed with toner having the same polarity as the charge polarity of No. 10 (in this embodiment, the belt photoconductor is negatively charged, and the toner has negative polarity).

At the start of image recording, the drive motor rotates and the belt photoreceptor 10 rotates clockwise via the drive roller 1, and the belt S is charged to the belt photoreceptor 10 by the charging action of the Y scorotron charger 11. The application of the potential is started. After a potential is applied to the belt photoreceptor 10, scanning exposure is started in the Y exposure optical system 12 by an electric signal corresponding to a first color signal, that is, an image signal of yellow (Y), and rotation of the belt (sub-scanning) is performed. ), An electrostatic latent image corresponding to the yellow (Y) image of the developed image is formed on the photosensitive layer on the surface. This latent image is reversely developed with the yellow (Y) developer adhered and conveyed onto the developing sleeve 131 by the Y developing device 13 in a non-contact state, and the belt photosensitive member 1
Yellow (Y) on the belt photoreceptor 10 according to the rotation of 0
Is formed.

Next, the belt photoreceptor 10 places an M scorotron charger 11 on the yellow (Y) toner image.
A potential is applied by the charging action of the M exposure optical system 12
The second color signal, that is, the scanning exposure with the electric signal corresponding to the magenta (M) image data is performed, and the non-contact reversal development by the M developing unit 13 causes the yellow (Y) toner image to be formed on the yellow (Y) toner image. A magenta (M) toner image is formed to overlap.

According to the same process, the cyan (C) toner image corresponding to the third color signal is further obtained by the C scorotron charger 11, the exposure optical system 12, and the developing device 13, and the K scorotron charger 11 , Exposure optical system 1
A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the second and developing units 13, and a color toner image is formed on the peripheral surface within one rotation of the belt photoconductor 10. You.

After the color toner image formed on the peripheral surface of the belt photoreceptor 10 is adjusted in potential by the scorotron charger 11A, the charge is removed by the pre-transfer exposure unit 16a.

On the other hand, the recording paper P as the transfer material is sent out from one of the paper feed cassettes 15A and 15B as the transfer material storage means by the corresponding feed rollers 15a and 15b, and is conveyed to the timing roller 15c.

The recording paper P is fed to the transfer area in synchronization with the color toner image carried on the belt photoreceptor 10 by the driving of the timing roller 15c, and is driven in the transfer area. A transfer roller 16b as a transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied opposite to the lower portion of the driving roller 1 for transfer, and the peripheral surface of the belt photoreceptor 10 Are collectively transferred to the recording paper P.

The recording paper P to which the toner image has been transferred is separated from the peripheral surface of the belt photoreceptor 10 along the curvature of the driving roller 1 and then conveyed to the fixing device 50, where a heater (not shown) is provided. ) And a pressure roller 52
The heat and pressure are applied between the rollers to fix the toner adhered to the recording paper P, and the discharge rollers 18a, 18
b, and is sent by the paper discharge roller 18 and discharged with the toner image surface on the recording paper P down to the paper discharge tray 20 which is also provided at the top and serves as an opening / closing lid for taking out the process cartridge 300. Is done.

The toner remaining on the peripheral surface of the belt photoreceptor 10 after the transfer is removed from the surface of the belt photoreceptor 10 by a cleaning blade 19a which is a cleaning member provided in a cleaning device 19 as a belt-shaped image carrier cleaning means. The rubbing is performed, the residual toner is removed and cleaned, and the formation of the toner image of the next original image is continued, or
Alternatively, stop temporarily and wait.

FIG. 2 shows a general configuration of the fixing device 50. The fixing roller 51 is a metal cylindrical roller whose outer periphery is covered by a silicon tube, and is a halogen heater H which is erected and fixed. Is included in the center of rotation, and is driven and rotated clockwise by power.

On the other hand, the pressure roller 52 is an elastic roller in which a silicon rubber layer is formed on the outer periphery of a cylindrical cored bar, and is pressed against the peripheral surface of the fixing roller 51 by urging means (not shown) to form a nip portion N. At the same time, the fixing roller 51 is driven to rotate by the rotational force.

The transfer paper P on which the toner image has been transferred onto the upper surface is conveyed to the fixing device 50 in the direction of arrow A, and the leading end thereof comes into contact with the outer periphery of the fixing roller 51. Welded.

The transfer paper P on which the toner is deposited is separated from the separation claw 51A.
Alternatively, the sheet is separated from the outer periphery of the fixing roller 51 or the pressing roller 52 by 52A, is conveyed in the direction of arrow B via the sheet discharging roller 53, and is discharged out of the fixing device 50.

A cleaning roller 54 and an oil application roller 55 are provided on the outer peripheral surface of the fixing roller 51. Unnecessary toner on the fixing roller 51 adhered at the time of welding the toner is removed by the cleaning roller 54. The silicone oil is applied by 55 to prevent the toner from adhering to the fixing roller 51 in advance.

(Embodiment 1) This embodiment is characterized by claim 1
The present invention relates to a color image forming toner used in a color image forming apparatus of a type in which color toner images formed by superimposing toner images of a plurality of colors are collectively fixed. A fixing means using an irradiation light system as shown in FIG. 3A is used instead of the heat roller system, and a so-called flash lamp system is also included in this.

Transfer paper P on which a color toner image is transferred on the upper surface
Is fed to the fixing area, the rod-shaped halogen lamp H is turned on, and the irradiation light of the halogen lamp H is combined with the light reflected by the reflector R to form an upper surface of the transfer paper P via a cylindrical condenser lens L. Almost the entire amount of emitted light is converged at right angles to the paper feeding direction, and the toner of each color reaches the softening temperature uniformly by the amount of heat of the irradiated light, melts, and partially penetrates the paper fibers.
When the paper exits from the area irradiated with the halogen heater, the toner temperature decreases due to heat conduction and radiation to the outside air, and the toner is solidified to complete the fixing.

The toner of each color forming the color toner image is composed of a pigment and a resin material called a binder. The pigment has a different absorptivity of irradiation light depending on the type of the color, and generally has a yellow (Y) ) Is the lowest, black (K) is the highest, and magenta (M) and cyan (C) are located approximately in the middle.

As a resin material constituting the toner of each color, for example, a copolymer of styrene and butyl acrylate is used, and by selecting a resin having a different molecular weight according to the type of the color of each pigment, a resin of each color can be obtained. The softening temperature of the toner is set, for example, as follows in accordance with the absorption efficiency of the irradiation light of each pigment.

Yellow (Y) 90 ° C. Magenta (M) 150 ° C. Cyan (C) 160 ° C. Black (K) 190 ° C. Since the absorptance differs depending on the wavelength, it cannot be uniquely determined. Melt at the temperature at that time. In the example, the softening temperature is set at a predetermined linear velocity and a light amount to be about 10 ° C. lower than the temperature at the time of exposing the unfixed image. These values must be experimentally determined each time depending on the type of pigment or resin, the linear velocity, the amount of light, and the like. The reason for the change depending on the linear velocity and the amount of light is because the balance between heat dissipation to the paper and the surroundings and heating changes.

The softening temperature of the toner of each color is determined by pressing a sample obtained by press-molding a resin material to be used under the conditions specified by an elevated type flow tester while applying a constant heating rate to the amount of drop of the plunger and the temperature. Calculated from the rising graph. FIG. 3 (b) shows an example, where the height T of the S-shaped portion of the graph is h, and the temperature T corresponding to the height of h / 2 is the softening temperature. Note that the temperature at which the sample starts to flow is defined as the flow start temperature.

The softening temperature can be set by a method of adding an additive having a different softening point to the resin material, a method of using a different kind of resin material, or the like.

The softening point (temperature) is an index of the viscoelastic properties of the toner. The intention of the present invention is to appropriately set the temperature dependence of the viscoelastic properties of the toner according to the temperature rise state of the toner color, and to select the softening point (temperature) as one expression thereof.

The toner of each color which has been uniformly melted by the irradiation of the halogen heater is transferred to the outside of the fixing region sequentially with the transfer of the transfer paper P, and is naturally cooled by outside air and solidified. Therefore, the color toner image is fixed in the same manner regardless of the toner color in a non-contact state all the time, so that the image is fixed as a high-quality image without deformation or blurring of the image due to pressure bonding.

(Embodiment 2) An embodiment of the invention according to claim 2 will be described with reference to FIG.

FIG. 4A is a longitudinal section of the fixing roller 51 incorporated in the fixing device 50, and FIG.
A, the fixing roller 51 is provided on the left and right side walls 5 of the container.
At 0A, it is supported via a bearing B and is driven and rotated by the power of the gear G of the motor shaft. On the other hand, the halogen heater included is supported between sockets mounted on the inner surface of the side wall 50A.

Near the outer periphery of the halogen heater H, four rods 151 having a square cross section are erected at parallel and symmetrical positions. Each rod 151 has an elastic plate 153 to which a thin reflector 152 is welded. It is fixed in an upright state in the axial direction at a predetermined interval.

The reflecting plates 152 are arranged such that the reflecting surfaces plated with gold or platinum face each other so as to be symmetrical with respect to the center of the fixing roller 51.

Two rods 154 and 155 having one end connected to the outside of the top of each reflector 152 are provided movably through the left and right side walls 50A, and each frame member is integrated with the connection. An integral eccentric cam C1 having a rotation phase different by 回 転 rotation is engaged with 156 and 157, respectively.

If the transfer paper P fed by the size detection signal of the transfer paper P or the manual size selection signal is judged or designated to have the maximum width _WMAX , the control unit controls the solenoid for driving the eccentric cam C1. Does not operate,
Therefore, each of the rods 154 and 155 is in the state shown in the figure, and each of the reflection plates 152 is in an upright state shown by a solid line. As a result, the halogen heater H causes the full length of the fixing roller 51 to be irradiated by the full length irradiation light. Heating is performed in accordance with the irradiation light distribution of the halogen heater H, and the transfer paper P having the width W _MAX is melted and fixed uniformly over the entire width of the toner.

On the other hand, if the transfer paper P is judged or designated to have the minimum width W _MIN , the control unit issues a command and the eccentric cam C 1 rotates by ２ by energizing the solenoid. The rod 154 is moved to the right by a predetermined amount, and the other rod 155 is moved to the left by a predetermined amount.

As a result, the projections 154 A of the rods 154 and 155 lie on the top of each of the reflection plates 152.
3 against the elasticity of the fixing roller 51 by a stroke set in accordance with the width W of the transfer paper P, whereby the respective reflection plates 152 are respectively provided at predetermined positions as indicated by a dashed line. Inclined to an angle.

Therefore, the irradiation light near the end of the halogen heater H is converged toward the center of the fixing roller 51, and as a result, the fixing roller 51 has a width W near the center due to the total irradiation of the halogen heater H. The area is efficiently heated, and the toner on the transfer paper P is quickly and sufficiently melted. Also, at the end of the fixing roller 51 through which the transfer paper P does not pass, an excessive rise in temperature can be avoided.

The other rods 254 and 255 and the eccentric cam C2 have the same configuration with respect to the other reflectors 152 arranged in the horizontal direction perpendicular to the respective reflectors 152 shown in FIG.
Are provided, and the operations of the eccentric cams C1 and C2 are performed in synchronization.

(Embodiment 3) An embodiment of the invention according to claim 11 will be described with reference to FIG. The image forming apparatus according to the present embodiment is a non-stack type double-sided image forming apparatus. Transparency for OHP (hereinafter, referred to as OHP paper) used as a transfer material is manually transmitted from the manual feed unit 42 described above. The paper is fed to the guide roller 43.

When the fed transfer material is determined to be an OHP sheet by the sheet detection sensor S2, the image forming section C
Is set to the single-sided image forming mode for
Is switched to the position indicated by the solid line.

The OHP sheet transfers the toner image formed on the photosensitive drum 21 in the image forming section C on the upper surface, and is fixed by the fixing roller 51 facing the fixing device 50, and is then switched over by the paper discharging roller 61. The sheet is conveyed along the inclined surface of the member 62 to the first reverse conveyance path 60, and is conveyed toward the switchback path 60a via the plurality of conveyance rollers R1.

The OHP sheet then enters the switchback path 60a by the conveying roller R2, and when the trailing end is detected by the sheet detecting sensor S3, the reversing switching member 62 changes to the angle indicated by the one-dot chain line, and the conveying roller R2 reverses. The rotation is switched, and the sheet is fed again with the image surface downward toward the sheet feeding path 44 via the second reverse conveying path 60b. Prior to refeeding, when the temperature of the pressure roller is low, only the fixing device is rotated, and the pressure roller is heated by the fixing roller.

The OHP sheet is again conveyed to the fixing device 50 by the rotation of the photosensitive drum 21 where the image formation has been interrupted, and the toner image on the underside of the OHP sheet, which has already been fixed by the fixing roller 51, is transferred to the silicone rubber layer And is fixed as a smooth and dense toner layer. As a result, the OHP sheet is discharged onto the discharge tray 64 via the discharge rollers 63 with the transparency of the image improved.

The fixing of the OHP sheet may be repeated twice or more depending on the toner density. It is also effective to incorporate an auxiliary heat source in the pressure roller 52 to control the temperature of the lower roller. By taking such measures, appropriate OHP fixing can be performed, and the set temperature of the fixing roller 51 can be set to a low temperature to improve durability.

Although the non-stack type sheet reversing device is used in the present embodiment, it is needless to say that the stack type can be applied, and the time required for various operations can be shortened when a plurality of OHPs are fixed. Yes, more desirable.

(Embodiment 4) An embodiment of the invention according to claim 14 will be described with reference to FIGS.

FIG. 6 shows a fixing device 50A in which the position of the fixing roller 51 facing the image side can be changed, and the rotating shaft 52S of the pressure roller 52 is used as a fulcrum on the outer surface of the container. A bracket-shaped swinging member 70A having a U-shape is provided, and an eccentric cam C3 rotated by a solenoid or the like is engaged with the elongated hole 71 thereof.

On the other hand, a pair of supporting members 80 integrated with the swinging member 70A via a connecting shaft 80A concentric with the fixing roller 51 penetrating the wall surface is provided on the inner side surface of the apparatus container. , A cleaning roller 54, and an oil application roller 55 are supported and supported between the support members 80.

The fixing device 50A is operated by a driving source dedicated to the fixing device different from a driving source for operating the image forming process. A gear G connected to the fixing device 50A is coaxial with the pressure roller 52. The power is transmitted to an integral 51G of the fixing roller 51 via an idle gear 52G.

The fixing roller 51 is kept in the position shown in FIG. 6A until the leading end of the conveyed transfer paper P is clamped in the nip portion N.
As shown in FIG. 5, the transfer paper P is maintained at a position immediately above the pressure roller 52, but after a lapse of a predetermined time since the leading edge of the transfer paper P is detected by the paper detection sensor S4, that is, by the upper and lower rollers of the transfer paper P by the nip N Simultaneously with the pinching, the eccentric cam C3 is gently rotated by 回 転, and as shown in FIG. 6B, the rocking member 70B is rotated clockwise while the formation of the nip N and the meshing of the gear system are maintained. At a predetermined angle.

Therefore, as shown in FIG. 6C, the fixing roller 51 is transported while being nipped and transported by the transfer roller P, with its position being changed from just above the pressure roller 52 to the entrance side of the transfer paper P, that is, upstream of the transport. The transferred transfer paper P abuts on the peripheral surface of the fixing roller 51 on the upstream side of the nip portion N, and then adheres along the peripheral surface. As a result, the transfer paper P is moved in the contact region m shown in the drawing prior to heating at the nip portion N. Also receives the preliminary heating of the fixing roller 51, so that a sufficient heating time can be taken and the fixing temperature of the fixing roller 51 can be set low, and the warming-up time can be shortened and consumed by lowering the set temperature. Power reduction is also achieved.

When the fixing operation proceeds and the trailing end of the transfer sheet P is detected by the sheet detection sensor S4, a predetermined time later, that is, the trailing end of the transfer sheet P comes out of the nip portion N, The eccentric cam C3 is further rotated by 1/2, and the swinging member 70A returns to the initial position, whereby the fixing roller 51 is again turned to the pressing roller 5 shown in FIG.
The transfer paper P is reset to a position for receiving the transfer paper P just before the transfer paper 2 before the transfer.

FIG. 7 shows the pressure roller 5 facing the non-image side.
2 shows a fixing device 50B capable of changing the position of the fixing device 51. A rotating shaft 51 of the fixing roller 51 is provided on the outer surface of the device container.
An "I-shaped" bracket-type swing member 70B having a fulcrum at S is provided, and an eccentric cam C3 rotated by a solenoid or the like is engaged with the long hole 71 thereof.

The oscillating member 70 B rotatably supports a rotation shaft 52 S of the pressure roller 52 protruding from the wall surface of the apparatus container, and at the same time, presses the peripheral surface thereof into pressure contact with the peripheral surface of the fixing roller 51.

The fixing device 50B is operated by a driving source dedicated to the fixing device different from the driving source for operating the image forming process, and a gear G connected thereto is integrated with the fixing roller 51. The power is directly transmitted to the gear 51G.

The pressure roller 52 is maintained at, for example, a position immediately below the fixing roller 51 as shown in FIG. 7A until the leading end of the conveyed transfer paper P is clamped in the nip portion N. Is a predetermined time after the leading edge of the transfer paper P is detected by the paper detection sensor S4, that is, simultaneously with the nip portion N holding the transfer paper P by the upper and lower rollers and the eccentric cam C
7 is gently rotated by ２, and the swinging member 70B is rotated clockwise by a predetermined angle as shown in FIG. 7B.

Accordingly, as shown in FIG.
Reference numeral 2 denotes a state in which the position of the transfer sheet P is changed from immediately below the fixing roller 51 to the discharge side of the transfer sheet P, that is, the transfer downstream side, while nipping the transfer sheet P. 51 and comes into close contact with the peripheral surface on the upstream side of the nip portion N.

As a result, before the transfer paper P is heated in the nip portion, the fixing roller 51
Will be heated.

In the fixing device 50B as well, after a predetermined time, that is, after the trailing edge of the transfer sheet P escapes from the nip portion N, the eccentric cam C3 is changed to the above state based on the signal of the trailing edge detection of the transfer sheet P by the sheet detection sensor S4. The swinging member 70B is further returned to the initial position by a half turn, whereby the pressure roller 52 is again returned to the position for receiving the transfer paper P before transfer immediately below the fixing roller 51 shown in FIG. Is set.

Also in the present embodiment, the transfer paper P is subjected to the preliminary heating of the fixing roller 51 even in the close contact area m shown in the drawing prior to the heating in the nip portion N, so that a sufficient heating time can be taken to fix the transfer paper P. The fixing temperature of the roller 51 can be set low, and by reducing the set temperature, the warm-up time can be reduced and the power consumption can be reduced.

The fixing roller 51 and the pressure roller 52
Since each of the separation claws 51A and 52A provided is contacted with the peripheral surface by elastic biasing, the contact state is maintained the same even if the position of each roller changes.

In this embodiment, the fixing device has a drive source separate from the image forming apparatus main body. However, the drive load fluctuates due to the change in the position of the roller, and this causes the speed fluctuation of the image forming means. This is to prevent the occurrence of
If the drive source and the transmission mechanism have a sufficient margin against load fluctuation, they may be the same drive source.

(Embodiment 5) An embodiment of the invention according to claim 22 will be described with reference to FIGS.

FIG. 8 shows a main part of the fixing device. FIG. 8 (a) is a top view of the fixing device, and FIG. 8 (b) is a sectional configuration diagram showing a supporting structure of a heat source included in the fixing roller. FIG. 9 is an explanatory diagram showing the distribution of the amount of heat of the fixing roller.

Generally, a halogen heater H is used as a heat source for the fixing roller 51. However, since the fixing roller 51 has a large heat loss from the end, the halogen heater H is used to change the winding density of the light emitting coil. As shown in FIG. 9A, the heat amount distribution of the fixing roller 51 by the irradiation light has a light emission characteristic such that the heat amount h2 at both ends is higher than the heat amount h1 at the center portion. Become uniform. When two halogen heaters H are included, the heat amount distribution of the fixing roller 51 is in a state where the heat amount is doubled as shown in FIG. 9B. If the transfer paper P having a small width W is continuously fixed, the heat of the fixing roller 51 at both ends is not consumed, and the temperature at both ends excessively rises, so that the deterioration is accelerated and the damage is easily caused.

The present invention solves this problem. Two halogen heaters H included in the fixing roller 51 of the present embodiment are connected to sliding members 90A and 90B which move on the upper surface of the fixing container, and are connected to the side walls. It is supported between supporting members 91 and 92 inserted through 50A.

Each of the sliding members 90A and 90B has a rack R on the opposite side meshed with a gear G driven by a driving source of the fixing device, and the rotation of the gear G in the clockwise direction causes the transfer paper P to move. They are symmetrically moved in opposite directions perpendicular to the transport direction.

When a manual designation signal of the size of the transfer paper P or a detection signal by a sensor is input to the control unit of the drive source, the rotation amount of the gear G is controlled in accordance with the width W of the transfer paper P, As an example, in the case of the minimum size, each of the sliding members 90A and 90B is moved to a symmetric position indicated by a dashed line in FIG.

As a result, the distribution of the amount of heat received on the fixing roller 51 side by the irradiation light of each halogen heater H is shown in FIG.
Since the phase is different as shown by the solid line in FIG. 7, the fixing roller 51 doubles the amount of heat in the central portion while keeping the increase in the amount of heat at both ends relatively small as indicated by the dashed line in the heat distribution of the entire length. It becomes possible.

Further, the halogen heater H is provided with a non-heat generating area extending in the moving direction as shown in FIG. It is desirable not to receive light. In this case, as shown in FIG. 10A, the halogen heater H is set in parallel with the transfer paper P having a small width W (W _MIN ), and the halogen heater H is set in parallel with the transfer paper P having a wide width W (W _MAX ). The heater H is placed at the moved position.

Further, as shown in FIG. 10B, a shielding plate can be attached to the terminal portion on the opposite side of the moving direction to prevent the irradiation light from being applied. In this case, as shown in the drawing, the halogen heater H is set in parallel with the transfer paper P having a large width W (W _MAX ), and the halogen heater H is provided for the transfer paper P having a small width W (W _MIN ). Will be placed in the moved position.

The heater is controlled based on the surface temperature of the fixing roller 51 measured by a non-contact temperature sensor installed in the paper passing portion. In the paper passing area, the heat to the halogen heater H is controlled according to the output of the temperature sensor. Supply is well controlled. Since there is no heat taken out by the transfer paper P outside the paper passing area, the temperature rises as compared with the paper passing area. Since the ratio of heat supplied at a position close to the heat outflow path increases, the temperature rise in the non-sheet passing area can be further reduced, and there is no practical problem. Further, since the heating range outside the paper passing area including the flange and the like is widened, the temperature rising speed is small, and when the number of small size paper passing is small (for example, about 10), the temperature rising amount is further smaller. Can be suppressed.

In this embodiment, the fixing paper is configured to move symmetrically with respect to the center of the temperature distribution. However, in an image forming apparatus in which the position of one end of the fixing paper is fixed and fed (one-side reference), the center position of the paper is fixed. Because of the change, the heat distribution is configured to be symmetrical with respect to the changed center.

With the configuration described above, even when small-size paper is continuously passed, it is possible to prevent roller damage due to an excessive rise in the temperature of the end roller, and to pass large-size paper after passing the small-size paper. It becomes possible to shorten the time until it becomes possible.

Although the present embodiment has been described with respect to an example in which the fixing roller includes a halogen heater, the present invention is also effective when the halogen heater is installed outside the fixing roller. This is particularly effective when a small iron material or the like is used or when rubber is coated.

[0103]

According to the first aspect of the present invention, it is possible to fix a color image on a transfer material by directly exposing with a halogen heater or the like, and such multicolor toners are preferable according to the second to sixth aspects. It was realized in a state.

Next, according to the present invention, the heat of the fixing roller can be efficiently converged in accordance with the size of the transfer material, and the heat can be supplied in accordance with the distribution of heat taken by the paper, and the offset at the end of the fixing roller can be reduced. Thus, the effect of increasing the durability of the fixing roller was produced. In addition, the focusing of the heat quantity is realized in a preferable state according to claims 8 to 10.

According to the eleventh aspect, a high-quality image with good translucency suitable for projecting with the OHP with respect to the transparency for the OHP is formed. 13 has been achieved in a favorable state by using a double-sided image forming apparatus having a sheet reversing device.

According to the fourteenth aspect, the fixing roller of the fixing device can heat the toner image on the transfer material at both the peripheral surface portion and the nip portion, so that the temperature of the fixing roller can be set low, and the warm-up can be achieved. This has the effect of shortening the time, reducing power consumption, and improving durability. In addition, the heating of the peripheral surface portion is realized in a preferable state according to claims 15 to 19 and 21, and the effect on the image forming process according to the embodiment of the present invention is avoided by claim 20.

Further, according to the present invention, the range of the fixing roller of the fixing device corresponding to the width of the transfer material is always adjusted to an appropriate temperature, and the durability is improved by preventing local overheating. Adjustment of the calorific value distribution is easily and reliably realized by claims 23 to 25, and abnormal temperature rise of the terminal portion of the heat source is prevented by claims 26 and 27.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus including a sheet reversing device.

FIG. 2 is a cross-sectional configuration diagram of a heat roller type fixing device.

FIG. 3 is a sectional configuration diagram and a graph of an irradiation light type fixing device.

FIG. 4 is a cross-sectional configuration diagram of a fixing roller including a reflection plate.

FIG. 5 is a cross-sectional configuration diagram of a sheet reversing device.

FIG. 6 is a diagram illustrating a position switching operation of a fixing roller.

FIG. 7 is a diagram showing a position switching operation of a pressure roller.

FIG. 8 is a diagram showing a position switching operation of a heat source.

FIG. 9 is an explanatory diagram illustrating a calorific value distribution of a fixing roller.

FIG. 10 is an explanatory view showing heat shielding means at a terminal portion of the heat source.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 belt photoconductor 11 scorotron charger 12 exposure optical system 13 developing device 21 photoconductor drum 24 transfer device 25 separator 42 manual feed unit 44 registration roller 50 fixing device 51 fixing roller 52 pressure roller 60 first reversing conveyance path 60a Switchback path 60b Second reversing conveyance path 62 Reversing switching member 70, 90 Swing member 80, 90, 91 Support member 151 Bar member 152 Reflection plate 153 Elastic plate 156, 157 Frame member C1-C3 Eccentric cam S1, S3, S4 Paper detection sensor S2 Paper detection sensor N Nip P Transfer paper

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/00 345 G03G 9/08 321 3/10 365 F-term (Reference) 2H005 AA01 AA06 AA21 CA04 CA21 EA03 EA06 FB01 FB02 2H033 AA11 AA46 BA08 BA58 BB18 BB21 CA17 CA26 3K058 AA86 BA18 DA02 DA06 EA02 GA06 3K092 PP18 QA01 QB27 QB42 QC70 RA03 RE10 SS47 VV22

Claims (27)

[Claims] 1. A color toner, wherein toners of respective colors used to form a color image by superimposing toner images of respective colors developed with toners of a plurality of colors have different softening temperatures according to the type of color. Image forming toner. 2. The method according to claim 1, wherein the softening temperature is set based on a temperature rise during irradiation of the fixing light source light.
4. The toner for forming a color image according to item 1. 3. The color image forming toner according to claim 2, wherein the softening temperature is set based on a level of a rising temperature when the fixing light source light is irradiated. 4. The color image forming toner according to claim 3, wherein the softening temperature is set by selecting a main resin material having a different molecular weight distribution. 5. The color image forming toner according to claim 3, wherein the softening temperature is set by using different additives. 6. The color image forming toner according to claim 3, wherein the softening temperature is set by selecting different main resin materials. 7. A fixing device for fixing a toner image by heating a fixing roller including a heater, wherein the fixing roller is provided with a variable angle reflecting member inside. 8. The fixing device according to claim 7, wherein the angle is changed according to the width of the transfer material to which the reflection member is fixed. 9. The fixing device according to claim 8, wherein the amount of change in the angle of the reflection member is set in accordance with the axial position of the fixing roller. 10. The fixing device according to claim 7, wherein the reflection member has a reflection surface plated with gold or platinum. 11. An image forming apparatus comprising a fixing device comprising a fixing roller for heating and a pressing roller pressed against said fixing roller, wherein said pressing roller has an elastic layer on its outer periphery, and has a toner image. An image forming apparatus, wherein the fixing roller is fused by heating the fixing roller, and then is fixed by being pressed against the elastic layer of the pressing roller. 12. The image forming apparatus according to claim 11, wherein the toner image passes through the fixing device at least once, and is fed again to the fixing device via a sheet reversing device. 13. The image forming apparatus according to claim 12, wherein the sheet reversing device is used for forming images on both sides of a sheet. 14. A fixing device comprising: a fixing roller for heating; and a pressing roller for pressing against the fixing roller, wherein a transfer material is sandwiched and conveyed between the fixing roller and the pressing roller to fuse the toner image. In the apparatus, a position of one of the fixing roller and the pressure roller is changed when the transfer material is nipped and conveyed. 15. The fixing device according to claim 14, wherein the position of the roller whose position is changed is changed on a circumference around the rotation axis of the other roller. 16. The fixing device according to claim 15, wherein the roller whose position is changed faces the image side during fixing. 17. The fixing device according to claim 16, wherein the roller whose position is changed is moved to an entrance side of the transfer material. 18. The fixing device according to claim 15, wherein the roller whose position is changed faces the non-image side during fixing. 19. The fixing device according to claim 18, wherein the roller whose position is changed is moved to a transfer material discharge side. 20. The fixing device according to claim 15, wherein a driving source of the fixing device is provided separately from a driving source of a main body of the image forming apparatus. 21. The fixing device according to claim 15, wherein the fixing device is provided with a detection unit for detecting the presence or absence of a transfer material in an entrance path of the transfer material. 22. A fixing device comprising: a fixing roller for heating; and a pressing roller for pressing against the fixing roller, wherein a transfer material is sandwiched and conveyed between the fixing roller and the pressing roller to fuse the toner image. In the apparatus, the fixing roller includes a plurality of heat sources, and the plurality of heat sources are movable in a direction perpendicular to a transfer material conveying direction. 23. The fixing device according to claim 22, wherein the plurality of heat sources are moved corresponding to a width of a transfer material to be fixed. 24. The fixing device according to claim 22, wherein the plurality of heat sources are paired, and each heat source is moved in directions opposite to each other. 25. The fixing device according to claim 24, wherein the plurality of heat sources are moved to symmetric positions with respect to a center line of a width of the transfer material. 26. The heat source according to claim 22, wherein the plurality of heat sources are halogen heaters, and each heat source has a non-heat generating area between a terminal portion at both ends and a central heat generating area. Fixing device. 27. The fixing device according to claim 22, wherein the plurality of heat sources are halogen heaters, and each of the heat sources has a terminal portion opposite to the moving direction covered by a shielding member.