JP2000025976A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality image by mounting a cooling means capable of cooling a surface roughing means as necessary, so as to prevent a transfer material from being wrapped around a roller or the delivered transfer materials from being made to adhere to each other. SOLUTION: A fan 46d, disposed near a radiation fin 46c, is activated to cool hydraulic fluid in a heat pipe through the fin 46c. A section facing the roller 44 of the heat pipe can be connected to or released from the roller 44 as necessary. A thermistor 48 is disposed on the roller 44 so as to detect the surface of the roller 44 and drive and stop a fan 46d based on its indication. The heat of the roller 44 is transferred to an extending part 46b and the fin 46c effectively by vaporizing the hydraulic fluid of the heat pipe 46 and cooled by the fan 46d. The surface temperature should be kept constant to keep the glossiness of a fixed image properly.

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 an electrostatic copying machine and a printer.

[0002]

2. Description of the Related Art A typical color image forming apparatus having a fixing device will be briefly described below with reference to the drawings. FIG. 3 is a schematic side sectional view of the color image forming apparatus, in which the inside of the apparatus has a transport system に わ た る extending from the right side of the apparatus main body to a substantially central portion, and a transfer described later included in the transport system. It comprises a latent image forming section に disposed near the drum and a developing section 〓.

[0003] The transport system will be described. This includes cassettes 2 and 3 arranged on the right side of the main body, paper feed rollers 4 and 5 for feeding the transfer material taken out therefrom, and a transfer drum 15 for feeding the taken out transfer material. Paper feed roller 6 to guide to
Transport guides 7 and 8 are provided.

The transfer drum 15 is rotating in the direction of arrow A in the drawing. The transfer drum and the outside thereof are provided with a contact roller 9, a gripper 10, a transfer material separating charger 11,
A separation claw 12 is provided, and a transfer charger 13 and a separation charger 14 are provided in the transfer drum 15. A transport belt 16 and a fixing device 30 are provided downstream of the separation claw 12 (as viewed in the transfer material traveling direction). The fixing device 3
On the downstream side of the printer 0 and outside the apparatus, there is provided a paper output tray 17 for receiving a completed hard copy.

Next, the latent image forming section 〓 will be described. The image signal of the yellow component color of the document projected from the laser scanner 24 onto the surface of the image carrier 19 uniformly charged by the primary charger 23 reaches the photosensitive layer on the surface of the image carrier 19 via the reflection mirror 25. An electrostatic latent image is formed.

The developing unit 現 像 includes a developing device 27Y containing yellow toner, a developing device 27M containing magenta toner, a developing device 27C containing cyan toner inside a rotating housing,
A developing device 26 having a developing device 27BK containing a black toner is provided. When the latent image formed on the image carrier 19 rotates in the direction indicated by the arrow B and reaches the developing site where the developing device 26 is disposed in proximity to the developing device, the developing device incorporating the yellow toner by this time. 27Y reaches the development site, and the yellow toner of the developing device 27Y is transferred to the latent image by the action of the development bias to form a yellow image.

The yellow toner image is transferred to the transfer drum 1 synchronously with the rotation of the image carrier 19.
5 reaches a transfer site arranged in contact with the image carrier 19. By this time, the transfer material taken out of the cassettes 2, 3 and the like reaches the transfer drum 15 in time with the toner image on the image carrier, is gripped by the gripper 10, and is brought into contact with the contact roller 9, It is electrostatically wound and adsorbed on the transfer drum 15 by the opposing electrodes and travels together with the transfer material.

When the transfer material reaches the transfer site, a transfer bias is applied to the transfer charger 13, and the yellow toner image on the image carrier is transferred (transferred) to the transfer material. Thereafter, the transfer material carrying the yellow toner image continues to rotate with the transfer drum.

On the other hand, the image carrier 19 after the transfer rotates, the residual yellow toner is removed by the cleaning device 21, and the residual charge is removed by the charge removing charger 20, so that the image carrier can start the next image forming operation. In this state, charging by the primary charger 23 and formation of a latent image with the magenta component color of the document are performed again.

Thereafter, as in the case of the yellow toner, a magenta toner image is formed by the developing device 27M, and the magenta toner image is superimposedly transferred onto a transfer material already supported by the transfer drum 15 and carrying the yellow toner image. Is performed. Similarly, the superimposition transfer of the cyan toner image and the black toner image onto the transfer material is performed, and the transfer ends.

When all the transfer is completed, the transfer drum 1
After the transfer material on 5 has been neutralized by the neutralization charger 14,
The sheet is separated from the transfer drum by the separation claw 12 and reaches the fixing device 30 by the transport belt 16. Here, the toner image on the transfer material is fixed and fixed on the transfer material as a color image, and then is discharged to the discharge tray 17.

Next, referring to FIG. 4, the fixing device 30 will be described.
Will be described. The fixing device includes a fixing roller 31 having a heat source 31a such as a halogen lamp therein, and a pressing roller 32 having a similar heat source 32a in pressure contact with the fixing roller 31.
And both rollers run synchronously in the direction of the arrow.

A thermistor 3 is provided on both rollers 31, 32.
The surface temperature of both rollers is maintained at a predetermined value by temperature control means (not shown) connected thereto.

In the vicinity of the fixing roller 31, a release agent applying device 33 for applying a release agent to the surface of the roller is provided. The apparatus has a release agent tank 33a containing silicone oil as a release agent, a pump 33b for pumping the release agent therefrom, and a coating roller for applying the lifted release agent to the fixing roller 31. The sponge is provided with an application roller 33c having a surface covered with silicone rubber. The roller 33c is used to control the amount of the release agent adhering to the surface by appropriately setting the contact angle with the roller 31. The blade 33d is arranged in contact.

The fixing roller 31 includes a roller 3
The portion of the nickel web 34a suspended between 4c and 34d engaging the intermediate roller 34b is
Has a portion that engages with the intermediate roller 35b of the Nomex felt 35a suspended between the rollers 35c and 35d,
The cleaning is performed by pressing each roller and gradually sliding the surface of each roller.

When a fixing operation is performed using such a fixing device, the amount of silicone oil as a release agent applied is about 30 to 40 mg / sheet for an A4 size transfer material. When a transparent OHP sheet is used as a transfer material at such a coating amount, there are problems such as a slimy feeling on the surface of the sheet and a decrease in light transmittance.

To cope with such a problem, proposals have been made to minimize the amount of oil applied. This will be described below. FIG. 5 is a side view showing the vicinity of the fixing roller showing such means. The end of the felt-like fiber member 38 is immersed in an oil pan, and the other end is brought into contact with the fixing roller 31. Oil is applied to the roller, and excess oil is removed by a blade 39 abutting downstream of the fiber member as viewed in the running direction of the roller 31.

With such a configuration, the amount of the release agent applied can be reduced to 10 mg or less per A4 size sheet. At the same time, when the amount of oil applied is reduced as described above, the glossiness of the image after fixing is increased, and the appearance is inevitably deteriorated.

The relationship between the amount of oil applied and the glossiness is shown in FIG. 6, where the glossiness is approximately 20% when the application amount is 40 mg / A4 size, while the glossiness is 10% / A4 size. The degree exceeds 30%.

Here, a method of measuring the glossiness will be briefly described.
As shown in FIG. 7, of the reflected light of the light flux that is incident on the surface of the transfer material P from the light source 40 at an angle θ and is reflected in the mirror-reflecting direction through the lens 42, The glossiness was measured by the ratio of the luminous flux entering 43 to the original luminous flux.

The reason why the glossiness decreases when the amount of oil is large is that the film thickness of the oil formed on the surface of the fixing roller is increased and acts as a heat insulating material. The toner is not transmitted to the toner, and the fixing is terminated while the melting of the toner is insufficient. As a result, the surface is left in a rough state by the unmelted toner particles, so that the gloss is reduced.

On the other hand, when the amount of oil is small, since the oil film is thin, the toner is sufficiently melted, the surface property of the fixed image is increased, and the glossiness exceeds 30%. In this case, it is possible to lower the glossiness of the image by lowering the temperature of the fixing roller, but if the fixing temperature is lowered, the surface temperature of the fixing roller becomes lower than the feasible temperature during continuous paper feeding. Therefore, there is a problem that a low-temperature offset occurs.

As means for solving such a problem, means for actively roughening the surface of an image has been proposed. FIG. 8 shows an example of such a surface roughening means.
To explain this, a roughing roller 44 having moderate fine irregularities on the surface is provided on the downstream side (as viewed in the traveling direction of the transfer material) of the fixing portion of the fixing device similar to that shown in FIG. A pressure roller 45 for pressing the roller is provided, and the transfer material after fixing is passed through the pressure nip between the two rollers to form fine irregularities on the image surface and reduce glossiness to obtain a good-looking image. It is configured as follows.

However, such a surface roughening means is:
Since it is located near the high-temperature fixing part, it is heated by the heat of the fixing part, so that the toner is transferred from the transfer material passing through the fixing part to the surface roughening means, and the transfer material is wound around the roughening roller. There were problems such as occurrence. Further, if the surface roughening means is heated to a high temperature, the transfer material passing therethrough is discharged in a heated state, so that the discharged transfer materials may adhere to each other due to the infusible toner, which is still satisfactory. The fact is that it has not been possible to get the desired results.

[0025]

SUMMARY OF THE INVENTION The present invention has been made in order to cope with such a situation, and has a fixing device utilizing a heating means, and a surface as described above is provided downstream of the fixing device. In an image forming apparatus provided with a roughening unit,
An object of the present invention is to provide an image forming apparatus capable of solving the above-mentioned problems such as image defects and processing inconvenience caused by disposing surface roughening means near the downstream side of the fixing device.

[0026]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a transfer material having a large number of fine irregularities on its surface downstream of a fixing device as viewed in the running direction of the transfer material. Image forming apparatus provided with a surface roughening means for roughing the surface of the transfer material by grasping and passing the image forming means, wherein a cooling means for cooling the surface roughening means as required is provided. Apparatus (1) or the above (1)
2. The image forming apparatus according to claim 1, wherein the cooling unit is a heat pipe which is brought into contact with and separated from the surface roughening unit and is cooled by a cooling fan. (1) In the image forming apparatus (3), wherein the cooling unit is a cooling fan that blows air to the surface roughening unit, or in the above (1), the cooling unit is In the image forming apparatus (4) or (1), the cooling means is the surface roughening means itself, which is provided inside the surface roughening means. An image forming apparatus (5), or an image forming apparatus (6) including the cooling unit according to any one of (1) to (5).

[0027] With this configuration, in an image forming apparatus for adjusting the glossiness by forming unevenness on the fixed transfer material by surface roughening means, a means for cooling the surface roughening means is provided. Therefore, it is possible to preferably avoid deterioration in image quality and inconvenience in handling due to a rise in temperature of the surface roughening means. [Detailed description of the invention]

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view of a main part of a surface roughening means showing an embodiment of the present invention. FIG. 8 shows a pair of surface roughening rollers disposed downstream of the fixing and pressing rollers (as viewed in the direction of travel of the transfer material) of the fixing device disposed in the image forming apparatus as shown in FIG. FIG. 4 is a perspective view showing one of the components, in which a heat pipe 46 is provided along an axial direction of a roller 44. The heat pipe 46 includes a portion 46a facing the roller 46 and an extended portion 46b deviated therefrom. The extended portion 46b is provided with a radiation fin 46c.

The fan 4 is located close to the radiation fin 46c.
6d is arranged, and by operating this, the working fluid in the heat pipe is cooled through the fins 46c. The heat pipe roller 44
The portion opposing the roller 44 can be moved toward and away from the roller 44 as needed. Further, a thermistor 48 is provided on the roller 44 to detect the surface temperature of the roller 44, and the fan 46d is driven and stopped according to the instruction.

With such a configuration, the heat of the roller 44 is efficiently transmitted to the extending portion 46b and the fin 46c by the vaporization of the working fluid in the heat pipe 46, and the fan 46d
Cooled by. In order to properly maintain the glossiness of the fixed image, it is necessary to maintain the surface temperature of the roller 44 constant, for example, to set the roller 44 surface temperature to 50. C, the surface temperature of the roller 44 is 5
0. In the case of C or more, the heat pipe 46 is brought into contact with the roller 44 to lower its surface temperature, and the roller surface temperature becomes 50. In the case of C or less, the surface temperature of the roller 44 is set to 50 ± 5 by increasing the surface temperature by separating the heat pipe 46 from the roller 44. C can be maintained.

This makes it possible to effectively prevent image deterioration such as uneven glossiness of the fixed image, offset of the toner with respect to the roller 44, winding of the transfer material around the roller 44, adhesion of the transfer materials, and inconvenience in handling. . Further, as a means for cooling the surface roughening roller 44, in addition to being separately provided from the roller as described above, the roller itself may be configured as a heat pipe, or a means such as mounting the heat pipe inside the roller. Similar results are obtained.

FIG. 2 shows another embodiment, in which a fixing device having a pair of fixing rollers 31, 32 and lower surface roughening rollers 44, 45 provided downstream thereof are shown. It is. The configuration and operation of the fixing device are the same as those of the fixing device shown in FIG. 4, and corresponding portions are denoted by the same reference numerals and description thereof will be omitted.

In this apparatus, the surface roughening rollers 44 and 45 are arranged in contact with the position where the fixed transfer material advances, so that the transfer material travels through the contact nip portion. Has become. The roller 44 is provided with a thermistor 48 for detecting the surface temperature of the roller 44. A cooling fan 47 is opened in the roller 44, and is operated in the same manner as in the above-described embodiment so that the roller 44 is appropriately cooled by a command from a thermistor 48 by control means (not shown). .

With such a configuration, the surface temperature of the roller 44 is 50 as in the above embodiment. When the temperature is equal to or less than C, the fan 47 is stopped. Fan 4 when C is exceeded
7 is operated to cool the roller, so that the roller surface temperature is 50 ± 5. It should be within the range of C.

As described above, according to the present invention,
Image forming in which a pair of surface roughening rollers is disposed on the downstream side of the fixing device in the transfer material traveling direction so that the fixed transfer material passes through the nip portion of the pair of surface roughening rollers. In the apparatus, since means for maintaining the surface temperature of the roller within a predetermined range is provided on at least one of the surface roughening rollers, offset and transfer of toner of the transferred transfer material to the surface roughening roller are performed. The material is wound around the roller. This has a remarkable effect of effectively preventing adhesion of the discharged transfer materials and obtaining a high-quality image.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration near a surface roughening roller according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a portion near a fixing device and a surface roughening roller, showing another embodiment of the present invention.

FIG. 3 is a schematic side sectional view of a known color image forming apparatus suitable for applying the present invention.

FIG. 4 is a side sectional view of a main part showing a fixing device similar to the above-described device.

FIG. 5 is a side sectional view of a main part of a fixing device using oil impregnated fibers as a means for applying oil to a fixing roller.

FIG. 6 is a graph showing a relationship between an oil application amount and a screen glossiness.

FIG. 7 is an explanatory view showing a glossiness measuring means.

FIG. 8 is a schematic side sectional view showing a known fixing device and a surface roughening roller.

[Explanation of symbols]

 REFERENCE SIGNS LIST 31 fixing roller 32 pressure roller 33 oil application device 34, 35 cleaning device 36 thermistor 44, 45 surface roughening roller 46 heat pipe 46c radiating fin 46d example fan 47 cooling fan 48 thermistor

Claims (6)

[Claims] 1. A surface roughening means provided downstream of a fixing device in a running direction of a transfer material, wherein the surface of the transfer material is provided with a large number of fine irregularities, and the fixed transfer material is gripped and passed to roughen the surface of the transfer material. An image forming apparatus, comprising: a cooling unit that can cool the surface roughening unit as needed. 2. An image forming apparatus according to claim 1, wherein said cooling means is a heat pipe which comes into contact with and separates from said surface roughening means and is cooled by a cooling fan. 3. The cooling means according to claim 1, wherein said cooling means is a cooling fan for blowing air to said surface roughening means.
The image forming apparatus as described in the above. 4. An image forming apparatus according to claim 1, wherein said cooling means is provided inside said surface roughening means. 5. An image forming apparatus according to claim 1, wherein said cooling means is said surface roughening means itself. 6. An image forming apparatus comprising the cooling means according to any one of claims 1 to 5.