JP2000338803A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic device which unnecessitates large amount of energy in a fixing process and can prevent room temperature from rising. SOLUTION: A fixing part 14 in the electrophotographic device is provided with a pair of heating rollers 31, 32, a pair of preheating rollers 41, 42 and a pair of endothermic rollers 51, 52. The heating roller 31 incorporates a heater 33, the preheating roller 41 and the endothermic roller 51 respectively incorporate preheating heaters 43, 53. The preheating roller 41 and the endothermic roller 51 are thermally connected by a heat conductive member 21 and the preheating roller 42 and the endothermic roller 52 are thermally connected by a heat conductive member 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic apparatus such as an electronic copying machine and an electronic printing apparatus.

[0002]

2. Description of the Related Art In such an electrophotographic apparatus, a photoconductive layer formed on an outer peripheral portion of an electrostatic drum is irradiated with a light beam to form an electrostatic latent image. The contact causes the electrostatic latent image to be developed as a toner image. The toner image attached to the photoconductive layer is transferred onto a sheet such as printing paper in a transfer step. Then, the toner image transferred onto the sheet is fixed on the surface of the sheet by the action of a heating roller that has a heater built therein and rotates in contact with the sheet.

Further, in a liquid electrophotographic apparatus which uses a liquid toner composed of a toner powder and a non-conductive solvent and develops an electrostatic latent image as a toner image by utilizing electrophoresis of the toner powder, The solvent is also removed from the sheet using the heating roller.

[0004]

In recent years, the printing speed of an image in such an electrophotographic apparatus has been increasing. For example, in an electrophotographic printing apparatus called a plateless digital printing apparatus or the like, the printing speed has been dramatically increased.

Therefore, in such an electrophotographic apparatus, it is necessary to use a heating roller having an increased heating capability so that the sheet can be sufficiently heated even when printing is performed at a high speed. For this reason, there arises a problem that an enormous amount of energy such as electric power is required.

Further, in such a high-speed electrophotographic apparatus, since a large amount of heated sheets are discharged inside the apparatus, the room temperature in the room in which the electrophotographic apparatus is installed rises and the environment deteriorates. There is also the problem of doing so.

An object of the present invention is to provide an electrophotographic apparatus which does not require a large amount of energy in a fixing process and can prevent a rise in room temperature. Aim.

[0008]

According to a first aspect of the present invention, a toner image is formed by transferring a toner onto a sheet to form a toner image, and then heating the sheet on which the toner image is formed to form a toner image. In an electrophotographic apparatus for fixing a sheet, a heater is built therein, and a heating roller for heating the sheet by rotating in contact with the sheet on which the toner image is formed, and a heating roller for the sheet conveying direction. A pre-heating roller disposed upstream of the heating roller and rotating in contact with the sheet; and a pre-heating roller disposed downstream of the heating roller in the sheet conveyance direction and rotating in contact with the sheet. And a heat conducting member for thermally connecting the preliminary heating roller and the heat absorbing roller.

According to a second aspect of the present invention, in the first aspect of the present invention, the same number of the preheating rollers and the heat absorbing rollers are provided, and the heat conducting member is The preliminary heating roller and the heat absorbing roller arranged at positions symmetrical with respect to the heating roller are thermally connected to each other.

According to a third aspect of the present invention, in the first or second aspect, at least one of the preheating roller and the heat absorbing roller has a built-in heater for preheating. .

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a main part of an electrophotographic apparatus according to a first embodiment of the present invention.

This electrophotographic apparatus has an image forming section 10 having an electrostatic drum 11 having a photoconductive layer formed on the outer periphery thereof.
And a transfer unit 13 having a transfer roller 12 that rotates in contact with the electrostatic drum 11, and a fixing unit 14, which is a characteristic part of the present invention.

A charging unit 15 for charging the outer periphery of the electrostatic drum 11 is provided around the electrostatic drum 11 in the image forming unit 10, and a light beam is applied to the outer periphery of the electrostatic drum 11 to irradiate the electrostatic drum 11. A recording head 16 for forming a latent image, a liquid toner supply unit 17 for supplying a liquid toner composed of a toner powder and a solvent to an outer peripheral portion of the electrostatic drum 11, and a charge elimination for the outer peripheral portion of the electrostatic drum 11 And a static elimination unit 18 for performing the operation.

In the image forming section 10, the outer peripheral portion of the electrostatic drum 11 rotating counterclockwise in FIG.
First, it is charged by the action of the charging unit 15. Next, the recording head 16 scans the outer periphery of the electrostatic drum 11 with a light beam to form an electrostatic latent image on the photoconductive layer on the outer periphery of the electrostatic drum 11. Then, the liquid toner supply unit 17
In the above, the photoconductive layer of the electrostatic drum 11 on which the electrostatic latent image is formed contacts the liquid toner composed of the toner powder and the non-conductive solvent, so that the electrostatic latent image is formed by electrophoresis of the toner powder. Is developed as a toner image. This toner image is transferred onto a sheet in the transfer unit 13.

That is, in the toner image formed in the image forming unit 10, the sheet conveyed along a sheet conveying path 19 by conveying means (not shown) is nipped by the electrostatic drum 11 and the transfer roller 12 in the transfer unit 13. At this time, the image is transferred from the outer peripheral portion of the electrostatic drum 11 to the surface of the sheet. Then, the toner image transferred to the surface of the sheet is fixed on the sheet in the fixing unit 14.

The fixing section 14 includes a pair of heating rollers 3.
1, 32, and the heating roller 3 in the sheet conveying direction.
A pair of pre-heating rollers 4 disposed upstream of
1, 42, and the heating roller 3 in the sheet conveyance direction.
A pair of heat-absorbing rollers 51 disposed downstream of
52, and a pair of heat conducting members 21 and 22.

The heating rollers 31 and 32 are for fixing the toner image transferred onto the surface of the sheet, and are configured to rotate in synchronization with each other by driving a motor (not shown). Note that these heating rollers 3
A heater 33 such as a halogen lamp is incorporated in the heating roller 31 disposed on the upper side of the heaters 1 and 32.

By rotating these heating rollers 31 and 32 in contact with the sheet, the toner image formed in the image forming section 10 and transferred to the sheet surface in the transfer section 13 is fixed to the sheet. Further, when the heating rollers 31 and 32 are rotated in contact with the sheet, the solvent supplied to the sheet together with the toner powder in the liquid toner supply unit 17 evaporates from the sheet to the atmosphere.

The preheating rollers 41 and 42 are for preheating the sheet before the sheet is heated by the heating rollers 31 and 32. The preheating rollers 41 and 42 are connected to the heating rollers 31 and 32 by driving a motor (not shown). It is configured to rotate in synchronization. Of these pre-heating rollers 41, 42, a pre-heating roller 41 disposed above is provided with a pre-heating heater, such as a halogen lamp, for pre-heating the pre-heating roller 41 and the like when the apparatus is started. 43 is built in.

The heat absorbing rollers 51 and 52 are for absorbing heat from the sheet heated by the heating rollers 31 and 32, and are synchronized with the heating rollers 31 and 32 by driving a motor (not shown). It is configured to rotate. Among these heat absorbing rollers 51 and 52, a heater 53 for preheating, such as a halogen lamp, for preheating the heat absorbing roller 51 and the like at the start of the apparatus is built in the heat absorbing roller 51 arranged on the upper side. Have been.

The heating roller 31 and the preliminary heating roller 41
The heat absorbing roller 51 is a metal roller whose surface is made of a metal such as aluminum, duralumin or magnesium alloy. On the other hand, the heating roller 32, the preliminary heating roller 42, and the heat absorbing roller 52
The surface of a metal roller similar to the heating roller 31, the preheating roller 41, and the heat absorbing roller 51 is coated with silicone rubber.

The preheating roller 41 and the heat absorbing roller 51 are thermally connected by the heat conducting member 21.
The preheating roller 42 and the heat absorbing roller 52 are thermally connected by the heat conducting member 22. More specifically, the heat conducting member 21 is in contact with both the preheating roller 41 and the heat absorbing roller 51, and the heat conducting member 22 is in contact with both the preheating roller 42 and the heat absorbing roller 52.

Each of the heat conducting members 21 and 22 has a heat pipe configuration in which a liquid as a heat medium circulates. Instead of adopting a heat pipe configuration, a metal having a high thermal conductivity may be used.

In the fixing section 14 having the above configuration, the sheet heated by the heating rollers 31 and 32 is cooled by contacting the heat absorbing rollers 51 and 52. On the other hand, the heat energy absorbed by the heat absorbing rollers 51 and 52 from the sheet is supplied to the preliminary heating rollers 41 and 42 via the heat conducting members 21 and 22. Then, the preliminary heating rollers 41 and 4 whose temperature has increased due to the thermal energy
The sheet 2 is preheated by abutting the sheet 2 on which printing has been performed later.

That is, the temperature of the sheet after the transfer of the toner image by the transfer section 13 is Ta,
The temperature of the sheet immediately after contact with the heating rollers 31 and 32 is represented by Tb,
Assuming that Tc is the temperature of the sheet necessary for performing the fixing and Td is the temperature of the sheet immediately after contact with the heat absorbing roller rollers 51 and 52, the heat absorbing rollers 51 and 52 correspond to [Tc−Td] from the sheet. Heat energy. The heat energy is transferred to the heat conducting members 21 and 2
The sheet 2 is sent to the heating rollers 31 and 32 via the heating roller 2 and is used as thermal energy corresponding to [Tb-Ta] for preheating the sheet.

Therefore, as the heating rollers 31 and 32, those having a heating capacity capable of increasing the temperature of the sheet from Tb to Tc may be employed. Here, considering that it is necessary to adopt a fixing unit having a heating capacity capable of raising the temperature of the sheet from Ta to Tc in the conventional fixing unit, the fixing unit 14 to which the present invention is applied , [Tb-T
a) whose heating capacity is small by the heat energy corresponding to [a], and energy saving corresponding to [Tb-Ta].

The temperature of the sheet discharged from the fixing section 14 to which the present invention is applied is Td. Here, considering that the temperature of the sheet discharged from the conventional fixing unit is Tc, the thermal energy discharged from the sheet to the room where the electrophotographic apparatus is installed is only the amount corresponding to [Tc-Td]. Less. Therefore, it is possible to solve the problem that the room where the electrophotographic apparatus is installed rises in room temperature and the environment is deteriorated.

Immediately after printing is started by the electrophotographic apparatus having the fixing unit 14 to which the present invention is applied, heat energy cannot be absorbed from the sheet by the heat absorbing rollers 51 and 52, and the heat absorbing rollers 51 and 52 cannot be used. Sufficient thermal energy cannot be sent from the roller 52 to the preheating rollers 41 and 42.

For this reason, immediately after the printing is started, the preheating roller 4 and the preheating heaters 43 and 53 built in the heat absorbing roller 51 are used.
1 and the heat absorbing roller 51 are heated in advance until a predetermined temperature is reached. When the temperatures of the preheating roller 41 and the heat absorbing roller 51 rise to a predetermined temperature after a predetermined time, the heating operation of the preheating roller 41 and the heat absorbing roller 51 by the preheating heaters 43 and 53 ends.

The preliminary heating roller 41 and the heat absorbing roller 5
1 is thermally coupled to the pre-heating roller 41 and the heat absorbing roller 51 instead of being built in both the pre-heating roller 41 and the heat absorbing roller 51 because the pre-heating roller 41 and the pre-heating roller The heat absorbing roller 51 may be incorporated in only one of the heat absorbing rollers 51. That is, the preheating heater may be built in at least one of the preheating roller 41 and the heat absorbing roller 51.

Next, another embodiment of the present invention will be described. FIG. 2 is a schematic diagram showing a main part of an electrophotographic apparatus according to a second embodiment of the present invention. In addition, about the member similar to 1st Embodiment mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The fixing unit 14 of the electrophotographic apparatus according to the second embodiment includes two pairs of heating rollers 31, 32 and 34,
35 is provided. These heating rollers 31, 32, 34,
Of the 35, heaters 33 and 36 such as halogen lamps are built in the heating rollers 31 and 34 disposed on the upper side.

The fixing unit 14 of the electrophotographic apparatus according to the second embodiment includes a pair of preliminary heating rollers 41, 42 disposed upstream of the heating rollers 31, 32 with respect to the sheet conveying direction. A pair of preliminary heating rollers 44, 45 disposed further upstream of these preliminary heating rollers 41, 42 with respect to the sheet conveying direction, and a pair of preliminary heating rollers 44, 45 downstream of the heating rollers 34, 35 with respect to the sheet conveying direction. And a pair of heat absorbing rollers 54 and 56 disposed further downstream of the heat absorbing rollers 51 and 52 with respect to the sheet conveying direction.

Of the pre-heating rollers 41, 42, 44, 45, the pre-heating rollers 41, 44 arranged on the upper side are provided for pre-heating the pre-heating rollers 41, 44 at the time of starting the apparatus. For example, heaters 43 and 46 for preheating such as a halogen lamp are incorporated. The heat absorbing roller 5
1, 52, 54, and 55, the heat absorbing rollers 51 and 54 disposed on the upper side include the heat absorbing rollers 5 when the apparatus is started.
Preheating heaters 53 and 56, such as halogen lamps, for preheating the elements 1 and 54 and the like are built in.

The preheating roller 41 and the heat absorbing roller 51 are thermally connected by the heat conducting member 21. Further, the preliminary heating roller 42 and the heat absorbing roller 52 are thermally connected by the heat conducting member 22. Further, the preliminary heating roller 44 and the heat absorbing roller 54 are thermally connected by the heat conducting member 23. Further, the preliminary heating roller 45
The heat absorbing roller 55 and the heat absorbing roller 55 are thermally connected by the heat conducting member 24. That is, the heat conducting members 21, 22, 2,
The reference numerals 3 and 24 respectively thermally connect the preliminary heating rollers 41, 42, 44 and 45 and the heat absorbing rollers 51, 52, 54 and 55 arranged symmetrically with respect to the heating rollers 31 and 34, respectively. Will be.

In the fixing section 14 of the electrophotographic apparatus according to the second embodiment, the heating rollers 31, 32, 34, 3
The sheet heated by 5 is cooled by first abutting on a pair of heat absorbing rollers 51 and 52, and is further cooled by abutting on a pair of heat absorbing rollers 54 and 55.

On the other hand, the heat energy absorbed by the heat absorbing rollers 51 and 52 from the sheet is supplied to the preheating rollers 41 and 42 via the heat conducting members 21 and 22 and the heat absorbing rollers 5 and
The thermal energy absorbed by the sheets 4 and 55 from the sheet is supplied to the preheating rollers 44 and 45 via the heat conducting members 23 and 24.

The pair of pre-heating rollers 44 and 45 and the pair of pre-heating rollers 41 and 42 whose temperature has been increased by the heat energy are sequentially brought into contact with a sheet to be printed later, thereby pre-heating the sheet. I do.

In the fixing section 14 of the electrophotographic apparatus according to the second embodiment, the heat conducting members 21, 22, 23, 2
Numeral 4 thermally couples the preliminary heating rollers 41, 42, 44, 45 and the heat absorbing rollers 51, 52, 54, 55, which are arranged symmetrically with respect to the heating rollers 31, 34, respectively. For this reason, the pair of heat absorbing rollers 51 and 52 and the pair of heat absorbing rollers 54 and 55 gradually cool the sheet, and this heat energy is used for the corresponding preliminary heating rollers 41 and 42.
The pair of pre-heating rollers 44 and 45 and the pair of pre-heating rollers 41 and 42 preheat the sheet in a stepwise manner while supplying the heat to the sheets 44 and 45 and utilizing the heat energy.

Therefore, according to the fixing unit 14 of the electrophotographic apparatus according to the second embodiment, it is possible to efficiently absorb heat from the sheet and efficiently preheat the sheet.

In the first and second embodiments, the preheating roller 4 provided on the lower side
2, 45 and the heat absorbing rollers 52, 55
24, the preheating rollers 42, 45 and the heat absorbing rollers 52, 5
5 is a contact with the back side of the sheet (the side on which the toner image is not fixed), so that the heat conducting members 22 and 24 disposed on the back side of the sheet can be omitted.

In each of the first and second embodiments, the heating rollers 31, 3
4, preliminary heating rollers 41 and 44 and heat absorbing roller 51,
The heaters 33 and 36 and the preheating heater 43 only for 54,
Although the heaters 46, 53, and 56 are built in, the heaters and preheating heaters may also be built in the heating rollers 32, 35, the preheating rollers 42, 45, and the heat absorbing rollers 52, 55 disposed below. .

[0043]

According to the first aspect of the present invention, since the heat conducting member for thermally connecting the preheating roller and the heat absorbing roller is provided, energy consumption can be minimized. Therefore, even when printing is performed at high speed by the electrophotographic apparatus, it is possible to use a heating roller having a small heating ability. Further, since the temperature of the discharged sheet can be lowered, it is possible to solve the problem that the room temperature in the room where the electrophotographic apparatus is installed rises and the environment deteriorates.

According to the second aspect of the present invention, the same number of the preliminary heating rollers and the same number of the heat absorbing rollers are provided, and the heat conducting members are arranged at positions symmetrical to the heating roller. Since the pre-heated roller and the heat-absorbing roller are each thermally coupled, the heat is efficiently absorbed from the sheet,
Further, the sheet can be efficiently preheated.

According to the third aspect of the present invention, since at least one of the preliminary heating roller and the heat absorbing roller has a built-in heater for preheating, the preliminary heating roller or the heat absorbing roller can be used for the preliminary heating roller or the heat absorbing roller immediately after printing is started. Even in a state where thermal energy cannot be sent to the heating roller, the sheet can be preheated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a main part of an electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a main part of an electrophotographic apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image forming part 11 Electrostatic drum 12 Transfer roller 13 Transfer part 14 Fixing part 15 Charging part 16 Recording head 17 Toner supply part 18 Static elimination part 19 Sheet conveyance path 21, 22, 23, 24 Heat conduction member 31, 32, 34 , 35 Heating rollers 33, 36 Heaters 41, 42, 44, 45 Preheating rollers 51, 52, 54, 55 Heat absorbing rollers 43, 46, 53, 56 Preheating heaters

Claims (3)

[Claims] 1. An electrophotographic apparatus for fixing a toner image to a sheet by transferring a toner onto a sheet to form a toner image and then heating the sheet on which the toner image is formed, wherein a heater is provided inside the electrophotographic apparatus. A heating roller that heats the sheet by rotating in contact with the sheet on which the toner image is formed; and a heating roller that is disposed upstream of the heating roller with respect to the sheet conveyance direction, A preheating roller that rotates in contact with the sheet; a heat absorbing roller that is disposed downstream of the heating roller with respect to the sheet conveyance direction and that rotates while contacting the sheet; the preheating roller and the heat absorbing roller An electrophotographic apparatus, comprising: a heat conducting member that thermally couples the two. 2. The electrophotographic apparatus according to claim 1, wherein the same number of the preliminary heating rollers and the number of the heat absorbing rollers are provided, and the heat conductive member is provided with respect to the heating roller. An electrophotographic apparatus for thermally connecting a preheating roller and a heat absorbing roller arranged at symmetrical positions. 3. The electrophotographic apparatus according to claim 1, wherein at least one of the preheating roller and the heat absorbing roller includes a heater for preheating.