JPH0736292A - Image forming device - Google Patents

Abstract

PURPOSE:To shorten the distance between a transferring part and a fixing part and to miniaturize an image forming device by placing a roller serving as a transferring roller as well as a pressure roller so as to come into press- contact with both an image carrier and a fixing means. CONSTITUTION:The image forming device is provided with the roller 200 served as the transferring roller as well as the pressure roller. The visible image on the photosensitive drum 101 is brought into contact with the recording material P, and transferred on the recording material P by the transferring and pressurizing common use roller 200 to which the voltage of 2 to 5kV having a polarity opposite to that of toner is applied by the power source 111. Then, the recording paper P is separated from the photosensitive drum 101 and transported to the nipping part of the heater 110 and the transferring and pressuring common use roller 200 formed through the fixing film 114. The transferring and pressuring common use roller 200 is provided with the iron core bar 202 and the silicone rubber material or the silicone rubber sponge is provided as the elastic layer 201 on the outer peripheral face of the core bar 202 being energized by the dispersion of carbon. Then, the heater 110 is held in pressurized contact against the transfer/pressure roller 200 by the energizing means.

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 such as a laser beam printer or an electrophotographic copying machine.

[0002]

2. Description of the Related Art As an example of a conventional image forming apparatus using electrophotography, there is a laser beam printer as shown in FIG.

In FIG. 10, 1 is a photosensitive drum (organic photoconductor, selenium, amorphous silicone, etc.) which is an image carrier, 2 is a charging roller, 3 is a laser beam, 4 is a developing device, 5 is a transfer roller, and 6 Is a cleaner, P is a recording material, and T is a toner.

In this laser beam printer, when a character or image information converted into an electric signal is output from a host computer (not shown), the image information is input to an interface controller (not shown) in the printer, Signal processing is performed by the controller. Then, the laser light 3 is emitted based on the processed data, and the laser light 3 is projected on the surface of the photosensitive drum 1 while scanning in the direction perpendicular to the rotation direction. This photosensitive drum 1
Is rotated in the direction a and is uniformly charged by the charging roller 2, so that the portion irradiated with the laser beam 3 is:
Since the charges on the photosensitive drum 1 are attenuated and the charges on the photosensitive drum 1 remain where the laser light 3 is not irradiated, an electrostatic latent image is formed according to ON / OFF of the laser light 3.

Next, the electrostatic latent image is conveyed to a position facing the developing device 4 by the rotation of the photosensitive drum 1, and is reverse-developed by the toner in the developing device 4 to be visualized.
On the other hand, in parallel with these operations, the recording material P is taken out one by one by a paper feed roller (not shown), and is timed by a registration roller (not shown), and a paper guide (not shown) is used. The photosensitive drum 1 and the transfer roller 5
Is conveyed to the opposite position. Therefore, the visible image on the photosensitive drum 1 comes into contact with the recording material P and is transferred onto the recording material P by the transfer roller 5 to which a voltage having a polarity opposite to that of the toner is applied. After that, the recording material P is separated from the photosensitive drum 1 by its own weight or other static eliminating means, and is conveyed to the nip portion between the heating element 10 and the pressure roller 11 formed via the fixing film 14. As a result, the toner image on the recording material P is subjected to heat and pressure to be fixed on the recording material P, and then discharged onto a tray (not shown). After the transfer process is completed, the photosensitive drum 1 is cleaned by the cleaner 6 to remove the residual toner (developer), and then enters the next image process.

In such a conventional laser beam printer, the photosensitive drum 1, the developing device 4, the transfer roller 5,
Since a means such as the fixing film 14 is required, the diameter of each means has been reduced to reduce the size of the entire apparatus.

[0007]

However, in each of the above-mentioned conventional examples, since a predetermined distance is provided between the transfer portion and the fixing portion, there is a limit to downsizing. Further, two rollers, a transfer roller in the transfer section and a pressure roller in the fixing section, are required, which is problematic in terms of cost and resource saving.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide an image forming apparatus which can be reduced in size and cost.

[0009]

According to the present invention, the above object is to provide an image bearing member carrying an unfixed developer image, and the unfixed developer image disposed so as to be in pressure contact with the image bearing member. An image forming apparatus including a transfer roller for transferring a recording material to a recording material, a fixing device that includes a heating means, and a fixing device that nips and conveys the recording material by a pressure roller to fix the unfixed developer image on the recording material. The transfer roller and the pressure roller are one roller, and are achieved by being arranged so as to be in pressure contact with both the image carrier and the fixing means.

[0010]

According to the present invention, the transfer roller and the pressure roller are also used as a single roller and are arranged so as to be in pressure contact with both the image carrier and the fixing means. The distance between and can be shortened, and the size of the image forming apparatus can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a first embodiment of the present invention. The apparatus of this embodiment is a laser beam printer. In FIG. 1, 101 is a photosensitive drum (organic photoconductor, selenium, amorphous silicone, zinc oxide, CdS, etc.) as an image bearing member, 102 is a charging roller, and 103 is a charging roller. Laser light, 104 is a developing device, 200 is a roller that also serves as a transfer roller and a pressure roller, 106 is a cleaner, and P is a recording material.

In this laser beam printer, when a character or image information converted into an electric signal is output from a host computer (not shown), the image information is input to an interface controller (not shown) in the printer, Signal processing is performed by the controller. Then, the laser beam 103 is emitted based on the processed data, and the laser beam 103 is projected on the surface of the photosensitive drum 1 while scanning in the direction perpendicular to the rotation direction. Since the photosensitive drum 101 rotates in the b direction and is uniformly charged by the charging roller 102, when the laser beam 103 is irradiated, the charge on the photosensitive drum 101 is attenuated and the laser beam 103 is emitted. Since the electric charge on the photosensitive drum 101 remains where it is not irradiated, the O
An electrostatic latent image corresponding to N or OFF is formed.

Then, the electrostatic latent image is formed on the photosensitive drum 101.
Is conveyed to a position facing the developing device 104 by the rotation of
Reversal development is performed by the toner in the developing device 104 to form a visible image. On the other hand, in parallel with these operations, the recording material P is taken out one by one by a paper feed roller (not shown), and is made to pass through a paper guide (not shown) while timing is adjusted by a registration roller (not shown). And is conveyed to a position where the photosensitive drum 101 and the transfer / pressure roller 200 are opposed to each other.
Therefore, the visible image on the photosensitive drum 101 comes into contact with the recording material P, and the polarity of the toner is 2 to 5 with the polarity opposite to that of the toner by the power supply 111.
Transfer / pressure roller 20 to which a voltage of kV is applied
0 is transferred onto the recording material P. After that, the recording material P is separated from the photosensitive drum 101 by its own weight or other charge eliminating means, and the heater 11 is formed via the fixing film 114.
0 and the nip portion of the transfer / pressurizing roller 200 is conveyed.

Inside the fixing film 114, there is provided a support (heater stay) 107 having high rigidity, high heat resistance, and high heat insulation with the longitudinal direction perpendicular to the running direction of the fixing film 114. A heating element 110 is attached above the support 107 via a heater stay 108. The heating element 110 is a linear or strip-shaped low-heat-conduction electric heating element provided by coating (screen printing, etc.) a uniform width of 1.0 mm with an electric resistance material such as silver palladium. On the other hand, a temperature detecting element 109 such as a thermistor is arranged on the opposite side of the heater stay 108, and the heating element 110 is energized from both ends in the longitudinal direction, and fixing can be performed while the temperature is detected by the temperature detecting element 109. It is carried out so as to maintain the temperature.

Therefore, the toner image on the recording material P is fixed on the recording material P under heat and pressure, and then discharged onto a tray (not shown). After the transfer process is completed, the photosensitive drum 1 is cleaned by the cleaner 6 to remove the residual toner (developer), and then enters the next image process.

Next, the transfer section and the fixing section in this embodiment will be described in more detail. The transfer / pressurizing roller 200 having the functions of the transfer roller and the pressure roller is an iron core 20.
2, the outer peripheral surface of the cored bar 202 is provided with a silicone rubber material or a sponge of silicone rubber which is the elastic layer 201, and is subjected to conductive treatment by dispersing carbon. The elastic layer 201 has a thickness of 4 mm and a volume resistance value of 10 ⁴ to 10 ⁹
It is a roller with medium resistance at Ω · cm. Of course, other heat resistant rubber may be used.

The heating element 110 is applied to the transfer / pressurizing / combining roller 200 with a contact pressure of 4 to 7 kgf by a biasing means (not shown) such as a spring via the endless belt-shaped fixing film 114. It is pressed against each other.

Since the fixing film 114 is repeatedly subjected to heat fixing of the toner, the fixing film 114 has excellent heat resistance, releasability and durability, and has a thickness of 40 μm or less. For example, a single layer film of heat resistant resin such as polyimide 25 μm
A thick or composite layer film, for example, a 20 μm thick film of polyimide, and PTFE or P on at least the image contact surface side
For example, a release coating layer in which a conductive material is added to a fluororesin such as FA is applied to have a thickness of 10 μm.

According to the apparatus of this embodiment as described above, the transfer / pressurizing roller 200 is provided with the photosensitive drum 101 and a support (heater stay) having high rigidity, high heat resistance, and high heat insulation.
Since it is sandwiched by 107, the bending of the roller can be suppressed. In particular, it is effective for a long roller that can print on a wide recording material. As a result, the difference between the nip at the time of transfer and the nip at the time of fixing can be reduced, and good transfer and fixing can be performed.

Further, Japanese Patent Application No. 3-10038 of the present applicant
As described in the specification of No. 9, the offset phenomenon of the fixing roller can be reduced by applying a voltage having a polarity opposite to the polarity of the toner to the pressure roller and applying an electric field in the direction of the pressure roller. As a result, dirt on the surface of the pressure roller is reduced. Therefore, also in this embodiment, the voltage application for the purpose of transfer can reduce the offset.

When the roller is placed in a place with high humidity, the roller absorbs moisture and its resistance decreases, and if a voltage for transfer is applied as it is, good transfer may not be performed or the photoreceptor may be damaged. However, in this embodiment, the heater for fixing is turned on before outputting an image to warm the endless belt-shaped fixing film 114, warm the transfer / pressurizing roller 200 to remove moisture, and set the roller to a predetermined resistance. Can be Therefore, the above problem can be solved.

Particularly when the photoconductor is an organic photoconductor which is weak against heat, the roller may be cooled by a fan 301, a Peltier element 302 or the like as shown in FIGS.

<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.

The transfer / pressure roller 203 of this embodiment
As shown in FIG. 4, an elastic layer 205 of a silicone rubber material or a sponge of silicone rubber is formed on the outer peripheral surface of the core metal 204.
Has a conductive treatment by the dispersion of carbon,
It has a volume resistance value of 10 ³ to 10 ⁴ Ω · cm. Further, on the outer periphery of the elastic layer 205, a PFA tube in which carbon is inserted to reduce the resistance is provided as a release layer 206, and the thickness thereof is 50 μm. As for the hardness, the roller having a solid silicone rubber has an Asker hardness of 50 ± 3 degrees, and the roller having a silicone rubber sponge has a hardness of 38.
± 3 degrees.

The resistance between the core metal 204 of the roller 200 and the surface is 10 ⁷ to 10 ⁹ Ω. Such a release layer 20
By providing No. 6, even if offset toner is attached to the endless belt-shaped fixing film 114, stains are less likely to adhere.

The photosensitive member 101a is an amorphous silicone rubber and has heat resistance. Generally, amorphous silicone photoconductors are sensitive to humidity, and when used in high humidity,
Since the image seems to flow, the moisture absorbed by the surface of the photoconductor is vaporized by attaching the drum heater. However, in this embodiment, the heater for fixing is turned on before the image is output, and the endless belt is turned on. Warm the fixing film 114
Since the photosensitive member can be warmed through the roller to vaporize the moisture absorbed on the surface of the photosensitive member, the drum heater is not necessary, and a good image is formed by the image forming means similar to that in the first embodiment.

<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, as shown in FIG. 5, a roll paper is used as the recording material P, and the toner contamination on the roller 200 is eliminated.

In an image forming apparatus using a large-sized recording material such as A0 and A1 machines, the length of the roller becomes long, so that the bending of the roller becomes large. However, according to the apparatus of this embodiment, the bending is small. it can.

As a modification, FIG. 6 shows an LED 1 as a light source.
03a, an apparatus for forming an image using the LED light 103b. As described above, according to the present invention, it is possible to make a laser beam printer, a PPC facsimile machine, or the like a small-sized device having a small ground area.

<Fourth Embodiment> Next, a fourth 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.

This embodiment is different from the first embodiment in the fixing position, and is provided with a process cartridge 100 in which a charging roller 102, a photosensitive member 101a and a developing device 104 are integrated. In addition, the separation claw 30 is provided for separating the paper after transfer.
Equipped with 3.

Generally, when the pressure between the transfer roller and the photoconductor is large, the character and the center are removed, but according to the present invention, the pressure of the cartridge 100 in the direction of the center of the roller 200 can be changed. Is good.

<Fifth Embodiment> Next, a fifth 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 fixing device is a heating roller system. The heating roller 304 contains a halogen heater 305 and is brought into pressure contact with the transfer / pressurizing roller 200 in the same manner as the fixing film 114.

<Sixth Embodiment> Next, a sixth 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 present invention is applied to a color laser printer, and a developing device 1 equipped with black toner is used.
04, a color developing device 104a having a cyan toner, a color developing device 104b having a magenta toner, and a color developing device 104c having a yellow toner. The black developing device 104 has the same configuration as that of the first embodiment.

The photosensitive drum 101a is made of amorphous silicone, and the photosensitive members 101b, 101c and 101d are made of organic photoconductor.

As described above, according to the present invention, the same effect can be obtained in the color laser printer.

[0041]

As described above, according to the present invention,
By using both the transfer roller and the pressure roller, the transfer unit and the fixing unit can be brought close to each other, and the image forming apparatus can be downsized. Also, by reducing the number of parts, cost reduction,
Resource saving can be realized. Further, the transfer roller and the pressure roller are also sandwiched between the image carrier and the fixing means, so that the bending of the roller can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a schematic configuration of an image forming apparatus including a roller cooling unit according to the first exemplary embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing a schematic configuration of an image forming apparatus including another roller cooling unit according to the first exemplary embodiment of the present invention.

FIG. 4 is a vertical sectional view showing a schematic configuration of an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a vertical sectional view showing a schematic configuration of an image forming apparatus according to a third embodiment of the invention.

FIG. 6 is a vertical cross-sectional view showing a schematic configuration of an image forming apparatus including an LED as a light source according to a third embodiment of the present invention.

FIG. 7 is a vertical sectional view showing a schematic configuration of an image forming apparatus according to a fourth embodiment of the invention.

FIG. 8 is a vertical sectional view showing a schematic configuration of an image forming apparatus according to a fifth embodiment of the invention.

FIG. 9 is a vertical sectional view showing a schematic configuration of an image forming apparatus according to a sixth embodiment of the present invention.

FIG. 10 is a vertical sectional view showing a schematic configuration of a conventional image forming apparatus.

[Explanation of symbols]

Reference Signs List 101 photosensitive drum (image bearing member) 101a amorphous silicone photosensitive member (image bearing member) 101b, 101c, 101d organic photoconductor photosensitive member (image bearing member) 110 electric heating element (heating unit) 114 fixing film (fixing unit) 200 , 203 Transfer / pressurizing roller 304 Fixing roller (fixing means) P Recording material

Claims (6)

[Claims] 1. An image bearing member carrying an unfixed developer image,
A transfer roller which is arranged so as to be in pressure contact with the image carrier and transfers the unfixed developer image onto a recording material, a fixing means including a heating means and a pressure roller, and the recording material is nip-conveyed and unfixed. In an image forming apparatus equipped with a fixing device for fixing a developer image to a recording material, the transfer roller and the pressure roller are one roller, and are arranged so as to be in pressure contact with both the image carrier and the fixing means. An image forming apparatus characterized by the above. 2. The image forming apparatus according to claim 1, wherein the rubber layer of the roller is a conductive heat resistant rubber. 3. The image forming apparatus according to claim 1, wherein the rubber layer of the roller is a conductive silicone rubber. 4. The image forming apparatus according to claim 1, wherein the roller has an outer layer of a conductive heat resistant tube and an inner layer of a conductive silicone rubber. 5. The image forming apparatus according to claim 1, wherein the roller has an outer layer of a conductive PFA tube and an inner layer of a conductive silicone rubber. 6. The image forming apparatus according to claim 1, wherein the image carrier is an amorphous silicone photoconductor.