JPH09171323A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color image forming device capable of performing fixation on a transparent sheet at a high speed, obtaining a high resolution, and securing the transparency of a color toner image by making the height of toner on material to be recorded which is pressed before passing through a fixing device and that on the material after passing through the fixing device satisfy a specified condition. SOLUTION: The transparent sheet being the material to be recorded 113 enters the press-contact part 209 of a pressing means from a direction shown by an arrow. By receiving bias electric field and pressing force, a pre-fixation image 205 is compressed to the height of toner h1 and charged. Furthermore, the sheet enters the press-contact part 204 (nip) of a fixing means. After the fixation in a heating roller 201 and a pressure roller 202, the image 205 becomes a post-fixation image 206, and the sheet is ejected from the fixing device. The height of toner at that time is h2. The relation between the height of toner h1 and h2 satisfies the condition h1/h2<=3.4, so that deforming compression amount applied to a toner layer becomes very little so as to obtain a high- resolution OHP image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming an image using an electrophotographic method, and more particularly to a color image forming apparatus used for forming a color image using contact heat fixing.

[0002]

2. Description of the Related Art Conventionally, in a fixing process of a color image forming apparatus, a heat fixing device such as a heat roller or a belt is used, and plain paper (thick letter, postcard, thin normal paper, etc.) is used as a recording material.
Alternatively, a transparent sheet (used for an overhead projector (hereinafter abbreviated as OHP)) is used, and in order to improve the color reproducibility of a plain paper color image or to secure the transparency of the transparent sheet, it is sufficiently heated and melted at the time of fixing. And was established. Therefore, a method of slowing the fixing speed or making the surface smooth is generally used.

For example, Japanese Unexamined Patent Publication No. 59-188673 describes that when a fixing rotator detects or designates a transparent sheet, the unmelted toner can be completely melted and fixed by switching the speed and slowing it down.

Further, in JP-A-62-235959, the fixing process is repeated so that the surface roughness is such that the frequency of unevenness is 8 cycles / mm or less and the amplitude is 9 μm or less to improve color reproducibility. The method is described. Also,
In Japanese Utility Model Laid-Open No. 63-73770, since the surface roughness of the heating roll is 0.1 μmRa or less, it is possible to obtain an image without black streaks and dots even when projected with an OHP, with a smooth surface without irregularities. Has been done.

Regarding the crushing of the toner by using the thermal fixing device, JP-A-6-230602 discloses that the toner height h1 / h2 before and after fixing is defined as 2 ≦ h1 / h2 ≦ 10 and the offset is set. Also, a method is described in which image stains due to offset and image stains during double-sided copying are less likely to occur.

[0006]

Conventionally, in fixing a color image, in general, the toner is largely deformed by applying a large amount of heat in order to ensure the color developability of the image by sufficiently melting and deforming the toners of a plurality of colors. Was there. In a transparent sheet such as an OHP sheet, this state was remarkable in ensuring transparency. For this reason, the fixing device and the image forming apparatus are large in size and consume a large amount of power, which is a problem. On the other hand, the advantage of the laser printer is its high speed,
When a transparent sheet is conveyed at high speed and fixed at high speed, heat cannot be sufficiently transferred to the transparent sheet, so the color toner image on the transparent sheet becomes opaque, and the projected image projected by OHP is black or considerably. The color will be close to black.

Therefore, in order to ensure transparency, the technique proposed in Japanese Patent Laid-Open No. 59-188673 is used, and when the transport speed of the fixing device is set slower when fixing the transparent sheet than when fixing the plain paper, It is necessary to switch various control constants such as control, pressure, and amount of oil applied, which causes the control device to be large-sized and expensive, and the user to be complicated to operate the switch. Further, in these fixing devices, since the printing speed of the transparent sheet is extremely slow, the high speed property of the laser printer cannot be utilized, and wasteful time is consumed, which is a problem.

Further, using the technique proposed in Japanese Patent Laid-Open No. 62-235959, when the fixing step is repeated so that the surface roughness is such that the frequency of unevenness is 8 cycles / mm or less and the amplitude is 9 μm or less. However, there is a problem in that the user performs complicated operations for re-fixing, wastes time, and takes a long time to obtain a print. Further, when the fixing process is automatically performed a plurality of times, the sequence becomes complicated due to the reversing operation, and a large reversing space is also required, which causes a large size of the apparatus, which is a problem.

Further, the technique proposed in Japanese Patent Laid-Open No. 6-230602 is an image using a magnetic toner, and no consideration is given to a color image, particularly a transparent sheet for color OHP. Also, using this technique, the toner is crushed, and the toner height h1 / h2 before and after fixing is 3.3 ≦ h
If 1 / h2 ≦ 10, the amount of deformation is too large and image distortion such as the collapse of fine lines occurs, the resolution deteriorates, and there is a problem that a clear image of electrophotography cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to fix a transparent sheet at a high speed, downsize the apparatus, reduce the amount of heat required, and suppress the amount of toner deformation. Another object of the present invention is to provide a color image forming apparatus having high resolution and capable of ensuring the transparency of a color toner image on a transparent sheet.

[0011]

In order to solve the above-mentioned problems, the color image forming apparatus of the present invention forms a plurality of non-magnetic toners of a plurality of colors on a recording material of a transparent sheet, and then heats and fixes them. An image forming apparatus for recording a multicolor image by
The toner height h1 on the recording material pressed by the pressing means before passing through the fixing device and the toner height h2 on the recording material after passing through the fixing device satisfy the condition of h1 / h2 ≦ 3.4. It is characterized by satisfying.

Further, the color image forming apparatus of the present invention is
The relationship between the toner height h1 and the toner height h2 is characterized in that the condition of h1 / h2 ≦ 2 is satisfied.

Further, the color image forming apparatus of the present invention is
The pressure P of the pressing means is 50 g / cm ² ≦ P.

Further, the color image forming apparatus of the present invention is
A primary transfer portion for sequentially transferring a color toner image visualized on a photoconductor to an intermediate transfer body, and a color toner image color-superimposed on the intermediate transfer body are collectively transferred onto a recording material. It is characterized in that it has a secondary transfer portion, and the pressing means is provided in at least one of the primary transfer portion and the secondary transfer portion.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments and drawings.

FIG. 1 is an explanatory view of the fixing means and the pressing means in the color image forming apparatus of the present invention.

The pressing means has a total load of 100 with respect to the pressing roller 207 from the back of the recording material 113 by pressing the pressing blade 208.
It is pressed with g to 700 g to form the pressure contact portion 209. still,
Although not shown, the pressing roller 207 and the pressing blade 20
Between 8 and 8, the bias electric field is applied in the direction in which the toner is separated from the pressing roller 207 and approaches the recording material 113. Further, the toner image is compressed at the pressure contact portion 209 to obtain an unfixed image 205.

Further, the fixing means is made of a metal cylinder having good heat conductivity such as aluminum and a rubber layer formed on the outer peripheral surface of the heating roller 201, and a heating body 203 such as a halogen lamp arranged inside the heating roller 201. And a pressure member composed of a pressure roller 202 having an elastic body such as silicone rubber formed on the outer peripheral surface of a metal shaft. The pressure rollers 202 are pressed against each other to form a pressure contact portion 204 of the fixing unit.

The transparent sheet, which is the recording material 113, enters the pressure contact portion 209 of the pressing means from the direction of the arrow, receives the bias electric field and the pressing force, and the pre-fixed image 205 is compressed and filled to the toner height h1. To be done. Further, the pressure contact portion 2 of the fixing means
04 (nip) and is driven to rotate by a driving device (not shown)
After the fixing is performed in (1), the post-fixed image 206 is discharged from the fixing device, and the toner height becomes h2.

First, although not shown, the toner image before pressing is laminated in a state in which there are many gaps between the toner particles and the packing density thereof is very low. When the toner image passes through the pressure contact portion 209 of the pressing unit, the bias electric field and the pressing force cause the toner to be compressed / filled only in the height direction without causing image deviation, and the toner height is compressed to h1 and the toner particles are separated from each other. Very few voids. Next, the toner image enters the nip of the fixing device with the toner height h1, heat and pressure are applied, the toner particles are deformed, and the toner particles are connected to each other in time, and the image after fixing has the image height h2 with the fixing device. It is discharged from, cooled and fixed.

In this process, the inventors have found that the toner height h1 before fixing has a great influence on the transparency in order to ensure the transparency of the transparent sheet, and the higher the packing density of the toner before fixing is, It was found that good transparency can be secured. That is, when the toner height h1 before fixing is small and the toner is in a high packing density state, the voids between the toners are small and the heat transfer in the toner layer is significantly improved. The toner particles are deformed, the toner particles are connected to each other, and not only the interface between the toner particles disappears,
Since there are originally few voids in the toner layer, it is possible to realize a high-density toner layer with very few voids in the molten toner layer and without bubbles. Therefore, it was found that an OHP image with few irregular reflections, black spots, and unevenness and having good transparency can be realized.

Further, since the toner height ratio h1 / h2 is small, the amount of deformation and compression applied to the toner layer can be very small, so that the image is not crushed and expanded, and the toner layer is not deformed due to collapse. It was also found that a high-resolution OHP image can be obtained. These cannot be achieved no matter how much the surface smoothness of the toner layer is improved or when the toner layer is deformed by applying a large amount of heat and a large amount of pressure.

In particular, when the value of the height h1 / h2 of the image before toner fixing is in the range of 3.4 or less, a clear image having good transparency and no image disturbance can be obtained. h1 / h2 is 3.
When it exceeds 4, the image is compressed and enlarged, and the image disorder becomes large, which is not preferable.

The pressing blade 208 is made of urethane or EP.
It is a conductive pressing blade that uses a mixture of carbon black and a conductive filler in DM, silicone rubber or the like. In order to ensure the uniformity of pressing, the pressing blade has a JIS-A hardness of 50 ° to 90 °. Nip at this time the pressure contact portion 209 is 0.2 to 2 mm, the pressure P1 in the nip is ^{50g / cm 2 ~500g / cm 2} . Further, the surface layer of the pressing blade 208 may be coated with conductive PFA or PTFE to reduce the friction coefficient and improve the paper passing property.

The heating roller 201 is provided with a layer of silicone rubber or fluororubber such as HTV, RTV, or LTV on a metal cylinder in order to improve contact with the recording material 113 such as a transparent sheet. In order to improve the peeling property, silicone or PFA may be coated or formed as a peeling layer by a tube. As the recording material 113, thin normal paper, plain paper such as thick letters and postcards, or a transparent sheet used for OHP is used.

Next, the structure of the color image forming apparatus of the present invention using the intermediate transfer member will be described with reference to FIG. The charging roller 102 holds the photoconductor 101 at a certain potential (for example, -7).
00V). A laser beam having a resolution of 600 dpi (dot per inch) formed by the exposure unit 103 is guided by the folding mirror 104 onto the photoconductor 101 to form an electrostatic latent image. Next, of the one-component contact type developing device 105 that can be contacted and separated in the direction of the arrow in the figure,
The yellow developing device 105Y is brought into contact with the other developing devices, and the negative charging yellow toner is reversely developed by the action of the electric field of a power source (not shown) to be visualized on the photosensitive member 101. The visualized yellow toner is ET
Intermediate transfer member 10 in which carbon is dispersed in FE (ethylene tetrafluoroethylene copolymer) and the resistance is adjusted to an appropriate value.
6, the primary transfer power source 108 for the primary transfer roller 107
A bias having a polarity opposite to that of the toner is applied by the toner and transferred by the action of the electric field, while the photoconductor 101 and the transfer roller 10 are transferred.
It is pressed by the pressure contact of 7. The transfer residual toner on the photoreceptor 101 is collected by a photoreceptor cleaner 109 which cleans the photoreceptor by bringing the blade into contact therewith, and then the photoreceptor potential is reset by a discharging lamp 110. By repeating the same operation for the magenta developing unit 105M, the cyan developing unit 105C, and the black developing unit 105K while synchronizing the position of the intermediate transfer member 106 and the light emission timing of the exposure unit 103, the toner of each color is formed on the intermediate transfer member 106. Are overlaid to form a full-color image. During this time, the secondary transfer roller 116 and the intermediate transfer member cleaner 119 are kept separated. On the other hand, the recording material 113 is a paper feed cassette 112.
From the sheet feeding means 111 to the registration roller pair 114, and is formed by the driving roller 115 and the secondary transfer roller 116 which can be moved in and away from the drive roller 115 in synchronization with the full-color image on the intermediate transfer body 106. It is conveyed to the secondary transfer portion. In the secondary transfer portion, in synchronization with the recording material 113, the secondary transfer roller 116 contacts the intermediate transfer member 106 to form and press the nip portion, and the primary transfer power source 10
The voltage determined by the calculation means 121 for calculating the voltage obtained from the control circuit 8 is controlled by the secondary transfer power source 117 at a constant voltage, and the electric field thereof forms a full-color toner image on the transfer material 113. After that, the recording material 113 is fixed to the fixing unit 120.
It is fixed by and discharged to the outside of the device.

FIG. 3A shows changes in toner height when a color toner image is formed using such an image forming apparatus.

As described with reference to FIG. 2, the respective color toners visualized on the photosensitive member are transferred onto the intermediate transfer member by the primary transfer roller and transferred up to a maximum of four colors to be superposed. At this point, the toner layer is transferred by the number of color superpositions, that is, four layers are transferred, like 301a. Since each toner layer is sandwiched between the photoconductor and the intermediate transfer member and transferred while being compressed by the pressing force of the primary transfer roller, the packing density of the lower toner layer becomes smaller as the number of color superpositions increases. Improve. After the color overlapping is completed on the intermediate transfer body, the toner image is transferred to the recording material while being pressed by the secondary transfer roller at the secondary transfer portion. At this point, the recording material 1 such as 302a
The toner on 13 is further compressed to the toner height h1, and the packing density of the toner is further increased. In particular, the upper toner layer having a low packing density at 301a is also sufficiently compressed and the packing density is increased. After that, the toner layer is fixed by the fixing unit 120 and has a height h2 like 303a.

As described above, in the color image forming apparatus using the intermediate transfer member, when the primary transfer portion and the secondary transfer portion are transferred by the contact transfer method, the toner image is compressed up to 5 times. Since the height h1 is small and the packing density of the toner is the highest, the gap between the toners is small, and the heat transfer of the toner layer is significantly improved. The particles are deformed, the toner particles are connected to each other, and the interface between the toner particles disappears. Moreover, since there are originally few voids in the toner layer, it is possible to realize a high-density toner layer having very few voids in the molten toner layer and no bubbles in the image after fixing. For this reason, it is possible to realize a 303a OHP image that has few irregular reflections and is uniform and has good transparency with little black spots or unevenness. Further, since there are few voids, there is little image unevenness such as image enlargement due to lateral displacement or collapse of toner, and high resolution image quality can be obtained.

The present invention is used in a tandem method or a color superposition method on a recording material in which a recording material is electrostatically adsorbed on a dielectric drum and each color toner visualized on a photoconductor is sequentially transferred. You can also do things. In this case, as shown in FIG. 3B, when the toner is transferred onto the recording material 113, the transfer section repeatedly repeats the number of color overlaps and receives high pressure to compress the toner layer 302b. It is formed on the recording material 113. Therefore, the packing density of the toner image before fixing is improved, and the fixed image having the toner image fixed thereon has few irregular reflections and is uniform and has good transparency with few black spots and unevenness.
An OHP image of 03b can be realized.

Further, the present invention can also be used in a color superposition method on a photoconductor in which toners of respective colors are sequentially visualized on the photoconductor and are collectively transferred onto a recording material by a transfer roller. In this case, as shown in FIG. 3C, the toner 301c on the photoconductor is
When the toner is collectively transferred onto the recording material 113, is pressed by the transfer roller and compressed under high pressure to form a toner layer 302c on the recording material. Therefore, the packing density of the toner image before fixing is improved, and the fixed image having the toner image fixed thereon can realize a 303c OHP image having few irregular reflections, black spots and unevenness, and good transparency.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0033]

EXAMPLE A color image forming apparatus used in this example is shown in FIG.
As shown in, the toner images on the photoconductor are sequentially transferred to the intermediate transfer body, and the color toner images with color superposition are collectively transferred to the transparent sheet that is the recording material, and then collectively transferred by the transfer roller at the secondary transfer section. did.

The fixing device used in this embodiment is shown in FIG.
As shown in FIG. 3, a transparent sheet as a recording material is nipped and conveyed in a nip between a pair of heating roller and pressure roller that are in pressure contact with each other, and the image forming surface of the sheet is in contact with the heating roller, and the heating member is placed inside the heating roller. A halogen lamp was arranged as a (heater) to perform fixing.

RTV rubber (outer diameter φ40 mm, wall thickness 1 mm) was formed on the outer peripheral surface of an aluminum cylinder (outer diameter φ38 mm, wall thickness 0.8 mm) as a heating roller, and silicon coating was further applied as a release layer.

Since the fixing device for color uses a soft heating roller, the heat resistance of the surface rubber is large and the fixing temperature is 18
If the temperature is not lower than 0 ° C., the temperature of the internal metal part exceeds 230 ° C. which is the heat resistant temperature of the adhesive part during continuous passage of narrow paper, and the adhesive part between the metal part and the rubber part melts and peels off. Therefore, the fixing temperature is preferably 180 ° C. or lower, and in this embodiment, the fixing temperature is 165 ° C.

As the pressure roller, a roller (outer diameter φ40 mm, wall thickness 4 mm) having a silicone rubber layer formed on the outer peripheral surface of the steel shaft by injection molding was used. The heating roller and the pressure roller were pressed against each other with a total weight of 30 kgf by a pressure means (not shown). The nip width was 4 mm, and the nip length in the axial direction of the pressure roller was 225 mm. Therefore, the pressure Pt is Pt = 30 / (0.4 × 22.5) = 3.3 kg
f / cm ² .

The heating roller was rotationally driven by a driving device (not shown), and the conveying speed was 180 mm / sec.
The environmental temperature was 20 ° C. and the environmental humidity was 50%.

The color toner used had a volume average particle diameter of 7 μm and a melting point (Tm) of 102 ° C. for each color. The melting point of the toner was measured by the flow tester method. In addition, the amount of monochromatic toner attached on the transparent sheet is 0.6 m.
g / cm ² , a 4 cm × 4 cm color batch was formed on a transparent sheet, and fixed at a predetermined fixing temperature and a conveying speed.

In this embodiment, HAZ is used as a measure of transparency.
E is used. Haze is a haze meter (NDH-10
01DP, manufactured by Nippon Denshoku Industries Co., Ltd.).
As is well known, the smaller the Haze, the higher the transparency. The transparent sheet is XEROXF made by FUJIXEROX.
ILM (REORDER No. V515) was used.
The image height before and after fixing was measured by using a laser microscope (1LM21W manufactured by Lasertec),
The level difference on the surface of the transparent sheet was measured.

Next, based on Table 1, a more detailed description of Examples 1 to 5 will be given. The image height h1 before fixing is
It can be changed by the pressure P of the transfer roller pressing portion. Pressure P
Is 40 g / c by changing the material, outer diameter, and total load of the transfer roller whose nip length in the axial direction is 210 mm.
It changed from m ^{2 to} 952 g / cm ² .

In Examples 1 and 2, a soft roller such as a sponge roller was used as the transfer roller in the secondary transfer section, and the pressure was applied with a total weight of 500 gf. Φ30 in Example 1
mm, and in Example 2, using a transfer roller having a diameter of 20 mm, the nip widths were 5.9 mm and 4.7 mm, respectively. In Example 3, the nip width was 2 mm by pressing the transfer roller in the secondary transfer portion with a total load of 1500 gf and using the transfer roller of φ20 mm. In Examples 4 and 5, the transfer rollers in the secondary transfer section were pressed with a total weight of 2500 gf and 3000 gf, respectively. φ15m
By using the transfer roller of m, the nip width was 1.4 mm and 1.5 mm, respectively. Each pressure P
Are shown in Table 1.

Table 1 shows the pressures P, h1, h1 / h2 and Haze when the toner adhesion amount and the fixing conditions are the same.
The relationship of image enlargement is shown.

[0044]

[Table 1]

From Table 1, when the packing density of the toner image before fixing is improved in the order of Examples 1 to 5, HAZ
It can be seen that E also decreases, and transparency improves even under the same fixing conditions.

When the toner height h1 before fixing is relatively large as shown in Example 1, h1 / h2 is 3.70,
Haze was 60, resulting in an opaque image, and image enlargement such as fine line collapse was large, and a clear image could not be obtained.

The toner height h1 before fixing is the second and third embodiments.
As shown in 4, when h1 / h2 is 3.40,
It is -2.20, and Haze becomes 45-22, and transparency improves. Further, the degree of image enlargement is reduced and a clear image can be obtained, which is sufficient for practical use. That is, good ranges were obtained in Examples 2, 3 and 4 in which the pressure P was 50 g / cm ² or more and h1 / h2 was 3.4 or less.

As shown in Example 5, the toner height h1 before fixing is relatively small, and when the image before fixing is well pressed, h1 / h2 is 2.0 and Haze is 18. , The transparency was good, the image expansion was small, and the resolution was good. That is, the pressure P is 952 g / cm
^When it is ² or more and h1 / h2 is 2.0 or less, the best image is obtained.

This is because the unfixed color toner deforms the toner particles when heat and pressure are applied, and eventually the toner particles are connected to each other, the interface between the toner particles (hereinafter referred to as a grain boundary) disappears, and bubbles in the toner layer occur. Disappears, while the surface of the toner layer becomes flat. According to this process, the transparency of the toner layer is improved. At this time, if the toner height h1 before fixing is small and the toner is in a high packing density state, the voids between the toners are small and the heat transfer to the toner layer is significantly improved. The toner particles are deformed, the toner particles are connected to each other, and the interface between the toner particles disappears. Also, since there are originally few voids in the toner layer, there are very few voids in the molten toner layer and there is no bubble or other high density toner. This is because layers can be realized.

When the pre-fixing image is pressed by the transfer roller of the secondary transfer section using the intermediate transfer member as described above, h1 becomes small and the packing density of the toner image becomes large, so that the high speed performance of the laser printer is sufficiently improved. It was possible to realize an OHP image having few irregular reflections, black spots and unevenness, and good transparency even at a speed at which it can be utilized.

Further, when a pressing roller is provided by applying a bias electric field while the recording material enters the fixing device from the secondary transfer roller and the reverse transfer phenomenon is suppressed and the toner layer is pressed, h1 becomes smaller and h1 / h2 was reduced, and a good OHP image with little image distortion could be realized.

Similar results can be obtained by changing the toner layer from a single color to a multicolor, and when h1 / h2 is 3.4 or less,
An image with good transparency and resolution was obtained, and a better image was obtained with h1 / h2 of 2 or less.

[0053]

According to the color image forming apparatus of the present invention,
By pressing the toner image in front of the fixing means to reduce the toner height h1 and increasing the packing density and reducing the voids in the toner layer, the thermal conductivity of the toner layer is increased, and the toner can be heated with a little heat and pressure. Is a high-density film without voids, so that the toner image on the transparent sheet can have a desired transparency and a good transparent image can be obtained. That is, since the toner height h1 before fixing is low and the toner layer does not contain air, the thermal conductivity is good and the toner melting proceeds rapidly, and sufficient color developability and transparency can be secured.

Further, the amount of deformation for sufficiently melting and deforming the toner is small, and it is not necessary to apply a large amount of heat to cause large deformation. Therefore, not only the fixing device but also the image forming apparatus can be downsized and power can be saved.

Further, since the toner height ratio h1 / h2 before and after fixing is small and the amount of deformation is small, it is possible to achieve a high-resolution transparent image without distortion due to image enlargement such as crushing of fine lines, and clear images of electrophotography can be obtained. It can also be obtained on a transparent sheet.

Further, since the toner height h1 before fixing is low and the toner layer does not contain air, the thermal conductivity is good and the high speed of the laser printer can be utilized, so that the fixing speed of plain paper and the fixing of transparent sheet are changed. Since it is not necessary, it is not necessary to switch among various control constants such as temperature control, pressure, and oil application amount, and the controller does not become large and expensive.
There is no need to give the user the trouble of operating the switch.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a fixing unit and a pressing unit in a color image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram of an example using an intermediate transfer member of the color image forming apparatus of the present invention.

FIG. 3 is an explanatory diagram of toner height of the color image forming apparatus of the present invention.

[Explanation of symbols]

 101 photoconductor 102 charging roller 103 exposure means 104 folding mirror 105Y yellow developing device 105M magenta developing device 105C cyan developing device 105K black developing device 106 intermediate transfer member 107 primary transfer roller 108 primary transfer power supply 109 photoconductor cleaner 110 charge removal lamp 111 paper feeding means 112 paper feeding cassette 113 recording material 114 registration roller pair 115 driving roller 116 secondary transfer roller 117 secondary transfer power supply 118 tension roller 119 intermediate transfer body cleaner 120 fixing means 121 computing means 201 heating roller 202 pressure Roller 203 Heater 204 Pressing part of fixing means 205 Image before fixing 206 Image after fixing 207 Pressing roller 208 Pressing blade 209 Pressing part of pressing means

Claims (4)

[Claims] 1. An image forming apparatus for recording a multicolor image by heating and fixing non-magnetic toners of a plurality of colors on a recording material of a transparent sheet, the pressing means before passing through the fixing device. Height h1 of the toner on the recording material pressed by the
And a toner height h2 on the recording material after passing through the fixing device satisfies a condition of h1 / h2 ≦ 3.4. 2. The color image forming apparatus according to claim 1, wherein a relationship between the toner height h1 and the toner height h2 satisfies a condition of h1 / h2 ≦ 2. 3. The color image forming apparatus according to claim 1, wherein the pressure P of the pressing means is 50 g / cm ² ≦ P. 4. The color image forming apparatus comprises a primary transfer section for sequentially transferring a color toner image visualized on a photoconductor to an intermediate transfer body, and a color superimposed on the intermediate transfer body. A secondary transfer portion for transferring a toner image onto the recording material all at once, and the pressing means is provided in at least one of the primary transfer portion and the secondary transfer portion. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a color image forming apparatus.