JP2000214701A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make obtainable a stable fixing capability and also to improve the printing speed in a fixing unit that is a non-contact type and uses warm air. SOLUTION: The device comprises an endless magnetic-toner image carrier 4 for transferring a magnetic toner image to a paper 14, formed on its own surface, by rotating in a direction orthogonal to the carried direction of the paper 14, and a fixing unit for fixing the transferred magnetic toner image to the surface of the paper 14. The fixing unit comprises a warm-air generation means H disposed on a carrying path for the paper 14 and used for blowing warm air toward the surface of the paper, and a magnetic-force generation means W disposed downstream in the carrying path for the paper 14 and opposite the warm-air generation means H. The magnetic toner image is melted with warm air by the warm-air generation means H and, at the same time, the magnetic toner can be attracted to the surface of the paper 14 with a magnetic force by the magnetic-force generation means W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus of an orthogonal transfer system using an electrophotographic technique, and more particularly, to a method for forming a toner image on a printing paper in a direction perpendicular to a conveying direction of the printing paper. The present invention relates to a fixing device structure in an image forming apparatus of an orthogonal transfer system for transferring images.

[0002]

2. Description of the Related Art In recent years, magnetic toner type image forming apparatuses capable of forming clear images with excellent resolution, such as laser printers, have been widely used. The applicant of the present application has already proposed such an image forming apparatus of the magnetic toner system, and has disclosed in Japanese Patent Application No. Hei 7-3286.
No. 00 was filed. This is because the paper is fed in a direction orthogonal to the loop direction of the magnetic toner image carrier in a loop, which repeats a process of forming a latent image by exposure and a process of developing the latent image with toner. The transfer is performed, and a fixing process is performed after the transfer.

FIGS. 4 to 6 are views showing the structure of an image forming apparatus proposed in the prior application. FIG. 4 is a schematic perspective view showing a main part of an image forming apparatus of an orthogonal transfer system, and FIG. FIG. 6 is a cross-sectional view of a main part showing a moving state of a transfer opposing roller of the image forming apparatus of the orthogonal transfer system.

In FIG. 4 and FIG. 5, an endless belt-shaped magnetic toner image carrier 4 having a coating layer of an organic photoconductive material or the like formed on the surface thereof is transferred to a transfer plate 15 on which a sheet 14 is mounted.
The roller 5 is stretched between the magnetic toner image carrier roller 5, the displacement roller 6, the transfer opposing roller 7, and the holding roller 8, which are arranged above. The toner image carrier 4 is capable of rotating around in the direction of arrow A in FIG. 4 by, for example, rotationally driving the toner image carrier roller 5, and its traveling direction is the feeding of the paper 14 indicated by arrow B in FIG. It is perpendicular to the paper direction.

In the circumferential direction of the toner image carrier 4, a cleaning device 11 for removing toner attached to the surface of the toner image carrier 4, a static eliminator 12 for removing residual charges, and a charge for forming a latent image are applied. A charger 9, an exposing device 13 for irradiating a laser based on the upper part of the image to form an electrostatic latent image on the surface of the toner image carrier 4, and a developing device 10 are arranged in this order. The developing device 10 applies the built-in toner 10a to the developing roller 1
0b causes the toner to adhere to the electrostatic latent image on the magnetic toner image carrier 4 and develop as a magnetic toner image 10c. Further, downstream of the transfer section, a fixing device 16 and a magnetic force generating section and lower guide 17 are provided.
Is disposed.

As shown in FIG. 4, a magnetic toner image carrier 4 having a coating layer of an organic photoconductive material or the like on its surface.
Is stretched between the magnetic toner image carrier roller 5, the displacement roller 6, and the transfer opposing roller 7, and circulates in the direction of arrow A. On the other hand, the paper 14 is supported on the transfer plate 15 and is transported in the direction of arrow B perpendicular to the direction of arrow A in which the magnetic toner image carrier 4 rotates.

In the transfer section having such a configuration, when an image forming operation is instructed by a control section (not shown) of the image forming apparatus, the magnetic toner image carrier 4 rotates in the direction of arrow A in FIG. First, after the surface is uniformly charged to about -600 V by the charger 9, an electrostatic latent image is formed on the charged portion by the exposure light beam 13a emitted from the exposure device 13 according to the content of the image to be formed. It is formed. The electrostatic latent image is developed by the magnetic toner 10 a when passing between the developing roller 10 b provided in the developing device 10 and the nipping roller 8, and the magnetic toner image 10 is formed on the toner image carrier 4.
c is formed.

By the above operation, the magnetic toner image 10c in the range corresponding to the image forming area L (see FIG. 5) of the paper 14
Is formed on the magnetic toner image carrier 4, the magnetic toner image 10 c is transferred from the magnetic toner image carrier 4 onto the paper 14. When transferring the magnetic toner image 10c, first, the magnetic toner image 10c formed on the magnetic toner image carrier 4 is transferred.
c is the end p2 of the image forming area of the paper 14
When the position is substantially the same as that of the above, the rotation of the magnetic toner image carrier roller 5, the displacement roller 6, and the transfer opposing roller 7 is stopped, and the rotation of the magnetic toner image carrier 4 stops.

Next, the paper 14 is moved on the transfer plate 15 by an arrow B.
The sheet is conveyed in the direction (see FIG. 4) to a predetermined position, and as shown in FIG. 6, the transfer opposing roller 7 moves in parallel along the sheet 14 in the arrow C direction from the transfer start position p3 to the transfer end position p4. As the transfer opposing roller 7 moves, the displacement roller 6 moves in the direction of arrow D so as to keep the tension of the toner image carrier 4 constant. At this time, the displacement roller 6 moves in the direction of arrow D so as to keep the tension of the magnetic toner image carrier 4 constant with the movement of the transfer opposing roller 7. Then, during the parallel movement of the transfer opposing roller 7, the magnetic toner image carrier 4 is sequentially pressed against the paper 14 by the transfer opposing roller 7,
The negatively charged magnetic toner image 10c on the surface of the magnetic toner image carrier 4 is transferred to the surface of the paper 14 on the transfer plate 15 to which a positive voltage is applied.

When one transfer is completed in this manner, the paper 14 is transported in the direction of arrow B by a distance corresponding to the effective transfer width M of the toner image carrier 4 shown in FIG. The carrier 4 rotates. Again, when the leading end of the magnetic toner image 10c on the magnetic toner image carrier 4 is substantially at the same position as the end of the image forming area L of the paper 14, the magnetic toner image 10c is similarly transferred onto the paper 14. You. At this time, the transfer opposing roller 7 moves in the direction opposite to the arrow C direction from the previous transfer end position p4, and moves parallel to the previous transfer start position p3 along the sheet 14 (FIG. 6).
reference). After the transfer, the sheet 14 is conveyed in the direction of arrow B by the same distance as the effective transfer width M shown in FIG. Further, in the portion of the magnetic toner image carrier 4 where the magnetic toner image 10c has been transferred, the remaining magnetic toner 10a is removed by the cleaning device 11 during the orbital operation, and thereafter, the remaining charge is eliminated by the charge remover 12. Is done.

As described above, the formation of the magnetic toner image 10 c on the magnetic toner image carrier 4, the transfer of the magnetic toner image 10 c to the paper 14, and the paper transport are repeated.
Is sent to the downstream fixing unit.

The fixing device 16 is arranged downstream of the magnetic toner image carrier 4 in the transport direction of the paper P with respect to the magnetic toner image transfer process. As shown in FIG. Is arranged below the conveyance path of the paper P, and a heating section 52 is provided on the upper side. The heating unit 52 includes a heater 53, a pair of hot air guides 54 a and 54 b disposed on both sides of the heater 53, and a fan 56 disposed above the heater 53 and driven to rotate by a fan drive motor 55. The sensor 57 is provided. The heater 53 is a light irradiation type such as a halogen lamp, a xenon lamp, a mercury lamp, an infrared heater lamp, or a resistance heating type using a nichrome wire or the like. The fan 56 is for blowing air to the heater 53 and uses a cross flow fan or the like.

In such a fixing device, the air supplied from the fan 56 in the direction of the arrow in FIG. To the surface of the paper 14. And
The unfixed magnetic toner on the surface of the sheet 14 passing over the guide 51 is heated and melted by the supplied warm air, and the magnetic toner image is fixed on the sheet 14. The temperature sensor 5
7, the temperature of the hot air is constantly detected, and the heater 53 is turned on / off so as to reach a predetermined temperature.

[0014]

However, in such a fixing device 16, the air supplied by the fan 56 is heated by the heater 53 to generate hot air, and the heat of the hot air causes the magnetic toner image to be melted. You. For this reason, the amount of heat applied to the paper and the magnetic toner per unit time is smaller than that of a fixing device using heat and pressure by a heat roller, which is recently used in many image forming apparatuses. Further, since there is no pressure for melting the magnetic toner into the paper, the fixing property is poor, and the fixing speed cannot be too high.

As described above, in the fixing in which the amount of heat is relatively small and there is almost no pressing force, both the melting of the magnetic toner image and the fixing power to the paper tend to be insufficient. Since this involves shading, a high-quality image cannot be obtained. On the other hand, it is conceivable that the amount of heat generated by the heater 53 and the amount of air blown by the fan 56 are increased to increase the temperature and flow rate of the warm air. However, if the temperature is excessively raised, there is a risk of ignition or smoking, and in the case of moisture-absorbing paper, there is a problem such as generation of wrinkles.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-contact type fixing device using hot air, which can attain stable fixing properties and improve the printing speed.

[0017]

The fixing device structure of the present invention comprises:
An endless magnetic toner image carrier that circulates in a direction orthogonal to the paper transport direction and transfers a magnetic toner image formed on its surface to the paper; and a magnetic toner image carrier in the transport direction of the paper from the magnetic toner image carrier. A fixing unit disposed downstream and fixing the magnetic toner image to the surface of the sheet, wherein the fixing unit is disposed on a sheet transport path, and the hot air is directed toward the surface of the sheet. And a magnetic force generating means disposed below the paper conveyance path and opposed to the hot air generating means, and the magnetic toner is generated by the hot air generated by the hot air generating means. At the same time as melting the image, the magnetic toner can be attracted to the surface of the paper by the magnetic force of the magnetic force generating means.

In such a configuration, in addition to the melting of the magnetic toner by the hot air from the hot air generating means, the magnetic toner can be attracted to the paper by the magnetic generating means and permeated into the paper cloth, thereby improving the fixing property. And the occurrence of uneven fixing can be prevented.

[0019]

According to the first aspect of the present invention, there is provided an endless magnetic toner image carrier that rotates orbits in a direction orthogonal to a sheet conveying direction and transfers a magnetic toner image formed on its surface to the sheet. An image forming apparatus including a body and a fixing unit disposed downstream of the magnetic toner image carrier in the sheet conveyance direction to fix the magnetic toner image on the surface of the sheet. Hot air generating means disposed on a transport path for blowing hot air toward the surface of the sheet, and magnetic force generating means disposed below the sheet transport path and opposed to the hot air generating means With
A fuser structure in the image forming apparatus, wherein the magnetic toner image is melted by the warm air generated by the warm air generating means, and the magnetic toner is attracted to the surface of the sheet by the magnetic force generated by the magnetic force generating means. Further, at the same time as the melting of the magnetic toner by the warm air generating means, the magnetic force generating means has an effect of improving the fixing stability and increasing the fixing strength by the attractive force of the magnetic toner to the paper side.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic longitudinal sectional view showing a fixing device according to an embodiment of the present invention and essential parts in the vicinity thereof.

In FIG. 1, a fixing device according to the present invention
4 and a magnetic force generating means W provided below the conveying path and at a position facing the hot air generating means H.

The hot air generating means H includes a blower section in which a fan 18 utilizing a cross flow fan or the like is built in a housing 18a, and a heating section in which a heater 17 disposed just below a lower end of the housing 18a is housed. Have. The heating section is formed by a rectangular container-shaped hot air guide 20 which is communicated with an opening at the lower end of the housing 18a and which is larger than the width of the paper 14 supplied and has an open lower end. The hot air guide 20 utilizes a heat insulating material, and a temperature sensor 57 is disposed at a lower end thereof.

The magnetic force generating means W is provided with a hollow guide housing 1 whose outer surface also serves as a guide for conveying the paper 14 as an outer shell. A coil 2 for generating a magnetic force is provided inside the guide housing 1.
Further, a magnetic force control unit 3 for controlling the energization of the coil 2 to set the strength of the generated magnetic force is provided.

FIG. 2 is an operation block diagram of an electric system in the fixing device of the present invention.

In FIG. 2, a microprocessor 21 for controlling the entire image forming apparatus, a ROM 22 for storing a program for controlling the entire image forming apparatus, a heater driver 23 for driving the heater 17, and a magnetic force control unit 3 are included. A magnet driver 25 for driving the coil 2, a fan driver 27 for driving the fan 18, an A / D converter 29 for converting an analog signal from the temperature sensor 4 using a thermistor or the like into a digital signal and inputting the digital signal to the microprocessor 21. Have. All these drivers 23,2
The microprocessors 5 and 27 are controlled by the microprocessor 21 according to a program previously stored in the ROM 22.

In the fixing device having the above-described structure, when the printing operation is started, first, the fan 18 starts rotating, and then the heater 17 is energized. An air flow is supplied to the heater 17 by the rotation of the fan 18, and the heater 1
The airflow is heated by the heat generated in 7 to be heated. The temperature of this hot air is monitored by a temperature sensor 57, and A
The digital value is detected by the microprocessor 21 via the / D converter 29. Since the power supply to the heater 17 is started at the same time as the start of the printing operation, the temperature of the air discharged from the lower end of the hot air guide 20 is not stable for the first time. Therefore, the apparatus waits until the air temperature detected by the temperature sensor 4 reaches a predetermined value, and then sends the sheet 14 onto which the unfixed magnetic toner image 10c has been transferred to the fixing device.

When the paper 14 passes between the hot air guide 20 and the guide housing 1, the unfixed magnetic toner image 10 c is melted by the supplied hot air, and at the same time, the current is supplied to the coil 2. The magnetic force is attracted to the surface of the paper 14. That is, as shown in FIG. 3, the unfixed magnetic toner image 10c on the surface of the paper 14
Is melted by the heat transfer from the hot air W supplied by being heated by the heater 17, and is pulled in the direction of arrow F by the magnetic force of the magnetic field generated by energizing the coil 2. Accordingly, since the unfixed magnetic toner image 10c is in a liquid state, the magnetic toner image 10c is not only melted by the warm air W but also easily penetrates into the cloth of the paper 14, stabilizing the fixing property, and preventing the unevenness of the image density from occurring. You. Then, when the magnetic toner image 10c passes through the fixing device, the magnetic toner image 10c is completely fixed on the surface of the paper 14 in a solid state.

As described above, in the present invention, even if the non-contact type in which the unfixed magnetic toner image 10c is not mechanically pressed to the paper 14 or heat transfer is not directly performed, the paper 14 The magnetic toner image 10c can be firmly fixed in a stable state, and good print quality can be obtained.

[0030]

According to the present invention, even when fixing is performed by melting unfixed magnetic toner using hot air, the magnetic toner can be attracted to the recording medium side by the magnetic force to increase the fixing power. A stable toner image can be fixed without increasing the temperature. Therefore, even in non-contact type fixing using hot air, high quality printing and high printing speed can be achieved by improving the fixing property.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a fixing device and an essential part in the vicinity thereof in an embodiment of the present invention.

FIG. 2 is an operation block diagram of an electric system in the fixing device of the present invention.

FIG. 3 is a schematic diagram for explaining warm air and magnetic force acting on magnetic toner in the fixing device of the present invention.

FIG. 4 is a schematic perspective view showing a main part of an image forming apparatus of an orthogonal transfer system.

FIG. 5 is a schematic view of a transfer unit viewed from a paper feeding direction.

FIG. 6 is a cross-sectional view of a main part showing a moving state of a transfer facing roller of the image forming apparatus of the orthogonal transfer system.

FIG. 7 is a schematic diagram showing the structure of a conventional fixing device in an image forming apparatus of the orthogonal transfer system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Guide housing 2 Coil 3 Magnetic force control part 4 Magnetic toner image carrier 5 Magnetic toner image carrier roller 6 Displacement roller 7 Transfer opposite roller 8 Nipping roller 9 Charger 10 Developing device 10a Magnetic toner 10b Developing roller 10c Magnetic toner image 11 Cleaning Apparatus 12 Static eliminator 13 Exposure device 13a Exposure light beam 14 Paper 15 Transfer plate 17 Heater 18 Fan 18a Housing 28 Blowing means 20 Hot air guide 21 Microprocessor 22 ROM 23 Heater driver 27 Fan driver 29 A / D converter 51 Paper guide guide 52 Heating section 53 Heater 54a, 54b Guide plate 55 Fan drive motor 56 Fan 57 Temperature sensor H Hot air generating means W Magnetic force generating means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Oda 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yasushi Kojima 1006 Kadoma Kadoma, Kadoma City, Osaka Pref. 72) Inventor Kenichi Uemura 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Masashi Ogawa 1006 Odaka Kazuma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1006 Kadoma Kadoma Matsushita Electric Industrial Co., Ltd. (72) Inventor Masanori Shibata 1006 Kadoma Kadoma, Osaka Prefecture F-term (reference) in Sangyo Co., Ltd. 2H033 AA20 BA07 BA25 BA58 BE00 BE02

Claims (1)

[Claims] An endless magnetic toner image carrier that circulates in a direction orthogonal to a sheet conveying direction and transfers a magnetic toner image formed on its own surface to the sheet; A fixing unit disposed downstream of the sheet conveying direction to fix the magnetic toner image on the surface of the sheet, wherein the fixing unit is disposed on the sheet conveying path and the surface of the sheet is A hot air generating means for blowing hot air toward the paper, and a magnetic force generating means disposed below the paper transport path and opposed to the hot air generating means, A fixing unit in the image forming apparatus, wherein the magnetic toner image is melted by wind and the magnetic toner is attracted to the surface of the sheet by the magnetic force of the magnetic force generating means. .