JP2003005479A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent blister from occurring at fixing time and to obtain a copy having high image quality. SOLUTION: This image forming device for forming a color image by using an electrophotographic method is equipped with a variable adjusting means for changing a fixing condition based on a means for detecting the moisture content of transfer material used in the image forming device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry electrophotographic transfer paper, and more particularly to a monochrome and color electrophotographic copying machine which reproduces image quality comparable to that of photographic printing.
The present invention relates to a dry electrophotographic transfer paper suitable for obtaining a high quality copy.

[0002]

2. Description of the Related Art Conventionally, electrophotographic color recording apparatuses have been digitized to achieve high image quality. Along with this, in the field of on-demand publications, in order to more easily publish a small number of copies, a color copying machine or a color printer is increasingly used. In addition, this printed matter is also being produced by a copying machine or a printer.

Coated paper generally used for printing is usually called art paper or coated paper, and has been used for forming high images. Also, in electrophotography, coated paper has become indispensable in order to obtain high image quality. However, when such coated paper is used in electrophotography, it has been found that blister (blister) is generated by heat and pressure applied by the fixing roller.

The blister phenomenon is caused by peeling of the paper layer when steam in the paper is heated and expanded because the air permeability of the coated paper for printing is usually small. For that, a coating containing a pigment having a large oil absorption having an average particle diameter of 1.5 μm or less in Japanese Patent Publication No. 5-82940 is applied to both sides of the base paper to form a coating layer,
A transfer sheet for dry electrophotography, which has been subjected to a smoothing treatment and adjusted to have a center line average roughness of the surface of the coating layer of 2.0 μm or less and an air permeability of 4000 seconds or less, is proposed. However, in the case of ordinary coated paper, the air permeability is about 6000 seconds, which is the view that such coated paper cannot be passed.

As a result, as a result of diligent examination of the coated paper used for general printing, the frequency of occurrence of blisters changes depending on the amount of water contained in the paper, which can be dealt with by changing the conditions of the fixing roller. I understood.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to improve the above-mentioned drawbacks of the prior art, and to prevent the occurrence of blisters at the time of fixing in dry electrophotography, and to obtain an electrophotographic transfer apparatus of high image quality. To provide.

[0007]

In an image forming apparatus for forming a color image using an electrophotographic method, a means for detecting the water content of a transfer material used in the image forming apparatus, and fixing based on the detecting means. An image forming apparatus comprising: a variable adjusting unit that changes the image forming apparatus.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a coated paper used in the present invention. As a base material, general paper such as acidic or neutral high-quality paper, neutral paper, waste paper, recycled paper may be used.

As for the coating layer to be coated on at least one side, common pigments such as heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfate, barium sulfate, and oxidation are used. Zinc, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin,
Mineral pigments such as aluminosilicate, sericite, bentonite, polystyrene resin fine particles, urea formaldehyde resin fine particles, hollow particles and other organic pigments may be used alone or in combination.

As the adhesive in the coating layer, a water-soluble adhesive which is generally used for coating and has a strong adhesive force with additives such as base materials and pigments, or emulsion or latex is used alone. it can. For example, polyvinyl alcohol,
Modified polyvinyl alcohol, starch, gelatin, casein, methyl cellulose, hydroxyethyl cellulose, acrylic acid amide-acrylic acid ester copolymer,
Acrylic amide-acrylic resin-methacrylic acid terpolymer, styrene-acrylic resin, isobutylene-maleic anhydride resin, water-soluble resin such as carboxymethyl cellulose, acrylic emulsion, vinyl acetate emulsion, vinylidene chloride emulsion, polyester emulsion , Vinylidene chloride emulsion, polyester emulsion, styrene-butadiene latex, acrylonitrile-butadiene latex, acrylonitrile-butadiene latex and the like are used.

With respect to the coating method, generally, gate roll coating, which is an on-machine coater, is performed, and size smoothing is performed by calendering to form a smoother surface property.

[0012] Further, off-machine coaters can be coated, and there are blade coating, air knife coating, roll coating, curtain coating and the like. However, the transfer material is formed by coating such as silk screen. Good.

Here, a multi-transfer type electrophotographic apparatus used for the transfer paper has been put into practical use. One example is shown in FIG. This apparatus has a yellow developing device 212, a magenta developing device 213, a cyan developing device 214, and a black developing device 215 that are attached and detached around the photosensitive drum 211 in the order of image formation, and a transfer material such as the above film is wound around the photosensitive drum. It has a rotatable transfer drum 207 for sequentially electrostatically transferring the toner image from the above, a charger 219 necessary for forming a latent image, an image exposure system E, and the like. This device 20
0, in the case of forming a full-color image, the transfer material P drawn from the paper feed tray 202 or the like is taken out in the direction of the arrow by the paper feed roller 205 or the like, and the conveyance roller 22
Transfer drum 207 by 0, 221, 222, 223
And is wound around the transfer drum 207 by electrostatic attraction by the attraction brush 208.

Then, toner images of a large number of colors are sequentially transferred from the photosensitive drum 211 to the transfer material P on the transfer drum 207 according to the image forming procedure. The transfer at this time is performed by the transfer brush 216. That is, the transfer drum 2 made of a dielectric sheet such as PVDF (polyvinylidene fluoride)
From the inside of 07, the transfer brush 216 is provided with an electric charge having a polarity opposite to that of the charging characteristic of the toner on the back surface of the transfer drum 207.
The electric field generated by the applied charges attracts toner to the surface of the transfer material on the dielectric sheet to transfer the toner.

Next, this transfer is repeated many times for each color toner of magenta (M), cyan (C), yellow (Y), and black (K), so that M, C, Y, and K are transferred onto the transfer material.
An image of each color is formed, and the transfer material is passed through the heat fixing device 218 to melt the toner of each color and mix the colors to obtain a full-color image.

The transfer material transport system comprises transfer material paper feed trays 201 and 202, 203 below the apparatus main body 200, and paper feed rollers 204 arranged substantially directly above the trays 201, 202 and 203. , 205, 206, and the transfer rollers 220, 221, 222, 223, which are disposed in the vicinity of the paper feed rollers 204, 205, 206, and are provided with the transport rollers 220, 221, 222, 223.
4, a separation charger 217, and a discharge charger 225 are provided, and the suction brush 208 and the transfer brush 21 are provided on the inner peripheral side.
6. A static elimination brush 226 is provided. A transfer drum 207 rotatable in the direction of the arrow in FIG. 2, a separation claw 227 near the transfer drum, a conveyor belt means 228 provided in the vicinity of the separation claw 227, and an end of the conveyor belt means in the conveyance direction. The thermal fixing device 218 is disposed in the vicinity of the side, extends to the outside of the apparatus body 200, and is adjacent to a discharge tray 229 that is detachable from the apparatus body 200.
Consists of.

The thermal fixing device 218 includes a fixing roller 230 having a heater therein and a pressure roller 2 facing the fixing roller 230.
31, a fixing agent applying device 232 for applying a releasing agent such as silicon oil to the fixing roller, and a cleaning 233 for the fixing roller.

During double-sided printing, the paper is conveyed in the direction D in FIG. 2 and folded back at the point of the reversing path 260 to double-sided unit 26.
1 is transported. Then, the sheet is fed by a sheet feeding roller 263 similar to the sheet feeding roller, and an image is formed in the same manner as the image forming method.

A moisture amount sensor 280, which is a moisture amount detecting means, is arranged in this apparatus, and the recording medium is fed from the sheet feeding cassettes 201, 202, 203 and the manual feeding cassette 209. The water content of
The control unit 290 is notified of the detection information.

FIG. 3 is a block diagram for briefly explaining the control structure of the color electrophotographic image forming apparatus shown in FIG. As shown in FIG. 3, the water content sensor 28 is attached to the paper feeding unit.
When 0 is provided and the water content is detected, a signal is sent to the control means 290 such as a microcomputer. Therefore, the control unit 290 controls the optimum variable adjustment for the fixing roller 230 and the pressure roller 231 according to the amount of water.

These specific conditions are shown in FIGS.
It is shown in the flowchart of the fixing condition change control of FIG. In this case, it is preferable to use a moisture content sensor that can detect in a short time, that is, a near infrared moisture meter. This is the amount of water that is detected by detecting the light that is absorbed depending on the water content of the substance.

Further, the water content of the recording material passing therethrough may be measured by installing the recording material in the paper feeding section, but a method of measuring the water content in the cassette containing the recording material may also be used.
Further, the moisture content sensor 290 has different light absorption rates depending on the basis weight, material, color and the like of the paper, so it is necessary to enter the data in advance.

In this embodiment, as shown in FIG.
First, when the copy button is pressed and the recording material is fed, the water content sensor 280 detects the water content of the recording material. Then, in the CPU as the control means, the optimum fixing speed is set based on the fixing speed varying means (not shown) by the matrix of the output values detected by the detecting means as described later.

The present invention will be described in more detail below with reference to Examples and Comparative Examples. The present invention is not limited to the examples. In this embodiment, the fixing roller 5
1 and a Si rubber roller as the pressure roller 52, the pressure force is set to 50 kgf and the nip width is 7.5 mm, and the NPI special art paper, the basis weight of 104.7 g / m ² (manufactured by Nippon Paper Industries) is used as the recording material. Fixing temperature 180 ℃, fixing speed 75mm / sec
Fixed in. The water content at that time was 7%. At that time, no blister occurred.

FIG. 5 shows a graph of the optimum conditions on the basis of this speed without causing blisters when the water content of the recording material changes. As shown in FIG. 5, when the water content was high, it was found that the blister peculiar to coated paper did not occur by increasing the speed. It was also found that when the water content is low, the fixing speed is slowed down and blisters do not occur.

Therefore, it is better to change the fixing speed condition as shown in FIG.
If there are only stages, by changing the fixing speed according to the water content according to the matrix shown in FIG.
After fixing, the blister peculiar to coated paper does not occur.

Since the optimum fixing temperature and the optimum fixing speed in this embodiment differ depending on the constitution of the fixing device, they are not necessarily limited to these values.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the moisture content of the recording material is detected, the fixing temperature is made variable by this, fixing is carried out at the optimum fixing temperature, and the occurrence of blisters after fixing is suppressed by the moisture content of the recording material. is there.

In this embodiment, as shown in the first embodiment, first, when the copy button is pressed and the recording material is fed, the water content sensor 280 detects the water content of the recording material. Then, in the CPU, the optimum fixing temperature is set by the fixing temperature control means (not shown) on the basis of the table detected by the detection means as described later.

Also in this embodiment, similarly to the first embodiment, Si rubber rollers are used as the fixing roller 51 and the pressure roller 52, the pressing force is set to 50 kgf and the nip width is 7.5 mm, and NPI special art paper is used. A recording material having a basis weight of 104.7 g / m ² (manufactured by Nippon Paper Industries) was fixed at a fixing speed of 75 mm / sec and a fixing temperature of 150 ° C. As a result, blisters did not occur after fixing. The water content of the recording material at that time was 7%.

A recording material having a water content of 6% is fixed at a fixing speed of 75.
The fixing was performed at a fixing temperature of 170 ° C. in mm / sec. as a result,
No blister occurred. FIG. 6 shows a matrix of the blister generation region depending on the water content of the recording material. In FIG. 6, when the water content is low, blisters do not occur even if the surface temperature of the recording material is raised, but when the water content is high, it is necessary to lower the surface temperature to suppress the occurrence of blisters.

As described above, in this embodiment, it is preferable to form an image at the optimum fixing temperature shown in the graph of FIG. 6 according to the water content of the recording material. However, in the temperature switching, if the matrix can be assembled only in three stages, for example, the fixing can be performed under the optimum fixing condition according to the temperature adjustment matrix shown in FIG. 6B, and the fixing temperature changes depending on the water content of the recording material. By doing so, generation of blisters after fixing is suppressed.

Since the optimum fixing temperature and the optimum fixing speed in this embodiment differ depending on the constitution of the fixing device, they are not necessarily limited to these values.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the amount of water in the recording material is detected, and the pressure applied between the fixing roller and the pressure roller is made variable by this,
By adjusting the nip width, fixing is performed under optimum fixing conditions so that blisters do not occur depending on the amount of water.

In this embodiment, the first embodiment and the second embodiment are provided.
First, when the copy button is pressed and the recording material is fed, the water content is detected by the water content detecting means.
Then, in the CPU, the optimum fixing condition is set by the pressing force varying means (not shown) on the basis of a table of output values detected by the detecting means as described later.

Also in this embodiment, as in the first embodiment, Si rubber rollers are used as the fixing roller and the pressure roller,
Pressing force is set to 480N and nip width is 7.5mm, NP
I special art paper, basis weight 104.7 g / m2 (made by Nippon Paper Industries)
The recording material is fixed at a fixing speed of 75 mm / sec and a fixing temperature of 170
It was fixed at ℃. As a result, blisters after fixing did not occur. The water content of the recording material at that time was 7.0%. Further, similarly to the first embodiment, the fixing roller,
A Si rubber roller is used as a pressure roller, and a pressing force of 686N,
When the nip was set to 8 mm and the water content was 6%, blisters did not occur. The optimum pressing force due to the change in the water content of the recording material is shown in the graph of FIG. See also FIG.
(B) shows a matrix when there are only three variable stages. In FIG. 7, it was found that when the water content of the recording material is high, the applied pressure tends to be low, and when the water content is low, the pressurization amount can be increased.

As described above, in this embodiment, it was found that blisters peculiar to coated paper can be prevented by fixing under the optimum conditions according to the water content of the recording material.

The optimum pressure in this embodiment is
Since it depends on the structure of the fixing device,
It is not limited to this value.

[0041]

As described above, the first aspect of the present application
According to the invention, before the recording material is conveyed to the fixing device,
This is a method of preventing blisters that tend to occur after fixing because the water content sensor of the recording material detects the water content and the fixing speed is set according to the water content.

Further, according to the second invention of the application, since the amount of water is detected and the fixing temperature is set for the amount of water, blisters that are likely to occur after fixing are prevented. Further, according to the third occurrence of the application, the amount of water is detected and the pressing force is set with respect to the amount of water, so blisters that easily occur after fixing are prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a transfer paper for electrophotography according to the present invention in a multiple manner.

FIG. 2 is a schematic sectional view of a full-color copying machine according to the present invention.

FIG. 3 is a block diagram for explaining the control configuration of FIG. 2 of the present invention.

FIG. 4 is a flowchart in an embodiment of the present invention.

FIG. 5 is a matrix of fixing conditions in the first embodiment of the present invention.

FIG. 6 is a flowchart in the second embodiment of the present invention.

FIG. 7 is a flowchart in the third embodiment of the present invention.

[Explanation of symbols]

218 Fixing device 230 fixing roller 231 Pressure roller 280 Moisture sensor 290 control means

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA12 DC02 DE02 DE07 DE09                       EA12 EB04 EC06 EC09 ED25                 2H030 AD04 AD16                 2H033 AA01 BA25 BA30 BA59 BB18                       BB28 BB34 CA07 CA12 CA13                       CA16 CA27 CA39 CA40

Claims (6)

[Claims] 1. In an image forming apparatus for forming a color image using an electrophotographic method, a means for detecting the water content of a transfer material used in the image forming apparatus and a speed of a fixing roller are changed based on the detecting means. An image forming apparatus comprising: a variable adjusting unit for controlling the image forming apparatus. 2. In an image forming apparatus for forming a color image using an electrophotographic method, a means for detecting the water content of a transfer material used in the image forming apparatus and the temperature of the fixing roller are changed based on the detecting means. An image forming apparatus comprising: a variable adjusting unit for controlling the image forming apparatus. 3. In an image forming apparatus for forming a color image using an electrophotographic method, a means for detecting the water content of a transfer material used in the image forming apparatus, and a pressing force of a fixing roller based on the detecting means. An image forming apparatus comprising: a variable adjusting unit that changes the image forming apparatus. 4. The image forming apparatus according to claim 1, wherein the transfer material passed through the image forming apparatus is a double-sided coated paper. 5. The image forming apparatus according to claim 1, wherein a fixing system for forming and fixing an image is a thermal pressing system. 6. The water content detecting means according to claim 1, wherein the water content detecting means is a detecting means for detecting the water content by measuring absorption of infrared rays or microwaves by the water contained in the recording material. Image forming device.