JP2005266167A - Image forming apparatus and intermediate transfer body used for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus of a small type whose energy consumption is less, the image forming apparatus being of a type in which toner transferred to an intermediate transfer body is melted under heat and transferred to a recording material. <P>SOLUTION: In the image forming apparatus of the system in which a toner image formed on an image carrier 1 is transferred to the intermediate transfer body 2 and then to the recording material 3, the intermediate transfer body 2 has a multilayer structure at least one layer of which is a heat insulation layer 2b containing ≥30% gas in volume ratio. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer using an intermediate transfer system, and more particularly to an improvement in an image forming apparatus for transferring molten toner and an intermediate transfer member used therefor.

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, a toner image is formed on a photosensitive drum, and then transferred onto an intermediate transfer member and transferred onto the intermediate transfer member. There is known a type in which the toner thus melted is heated and melted, and the melted toner is transferred and fixed onto a recording material such as paper.
In this type of image forming apparatus, since the heat capacity of the intermediate transfer member is usually large, large heat energy for heating the intermediate transfer member is consumed when the toner on the intermediate transfer member is heated. For this reason, the toner cannot be melted within the range of power normally used in a general copying machine or printer, and it is difficult to realize an image forming apparatus of a type in which the toner is heated and melted and transferred and fixed. On the other hand, in an apparatus equipped with electric power capable of melting the toner, due to the heat capacity of the intermediate transfer member, the heated intermediate transfer member cannot be cooled down and is in contact with the photosensitive drum while being stored, thus increasing the temperature of the photosensitive drum. The toner may stick to the photosensitive drum.

In order to solve these problems, a method has been proposed in which the heat capacity at the heating portion of the intermediate transfer member is reduced to increase the heating efficiency for the toner on the intermediate transfer member, and the heat storage on the intermediate transfer member is minimized. (For example, refer to Patent Document 1).
In Patent Document 1, a belt-like member is used as an intermediate transfer member, the intermediate transfer belt is made to circulate around the rotation support drum, and a part of the intermediate transfer belt is separated from the rotation support drum at the heating portion. Heating is performed from the back surface of the intermediate transfer belt.

JP 2001-183923 A (column of embodiment of the invention, FIG. 1)

However, in the technique presented in Patent Document 1, it is necessary to rotate the intermediate transfer member away from the rotation support drum, or a heating source is disposed inside the intermediate transfer member. There is a problem of increasing size and complexity.
The present invention has been made to solve the technical problems as described above, and heat-melts the toner transferred onto the intermediate transfer member, and transfers the molten toner to a recording material. The present invention provides a small-sized image forming apparatus that consumes less energy for melting toner and an intermediate transfer member used therefor.

  That is, according to the present invention, as shown in FIGS. 1A and 1B, the toner image formed on the image carrier 1 is transferred to the intermediate transfer member 2, and the toner image on the intermediate transfer member 2 is transferred to the recording material. 3, the intermediate transfer member 2 has a multilayer structure in which at least one layer is a heat insulating layer 2 b containing gas at a volume ratio of 30% or more. is there.

In such technical means, the image forming apparatus according to the present invention may be full-color or monochrome, and the image carrier 1 may be a photoconductor, dielectric, or the like as long as it can carry an image. It may be selected, and the form thereof may be either a roll shape or a belt shape.
Further, the intermediate transfer body 2 may be in the form of a roll or a belt, but is preferably a roll from the viewpoint of maintaining a stable structure of the heat insulating layer 2b. Furthermore, it is preferable to provide heating means 4 for heating and melting the toner when the toner on the intermediate transfer body 2 is melted and transferred to the recording material 3.

And the heat insulation layer 2b of this case is trying to reduce thermal conductivity by including gas, such as air, in the heat insulation layer 2b, in order not to transmit the heat | fever of the surface side of the heat insulation layer 2b easily. is there. Therefore, as a typical aspect of the heat insulating layer 2b, a sealing body is used between both ends of the layer sandwiching the heat insulating layer 2b (corresponding to the holding layer 2a and the elastic layer 2c in FIGS. 1A and 1B). The aspect comprised by the sealed hollow layer is mentioned. On the other hand, in an embodiment in which an elastically deformable conductive foam is used as the heat insulating layer 2b, the conductive foam preferably has heat resistance that can withstand the heat heated by the heating means 4. . Here, the term “conductivity” is sufficient if the toner image from the image carrier 1 is electrostatically transferred onto the intermediate transfer member 2.
Furthermore, from the viewpoint of maintaining the heat insulating property of the heat insulating layer 2b, the volume ratio of the gas may be at least 30%, more preferably 50% or more.

Further, an elastic layer 2c made of a conductive elastic body is provided below the heat insulating layer 2b of the intermediate transfer body 2, so that the opposite portion between the image carrier 1 and the intermediate transfer body 2, the intermediate transfer body 2 and Sufficient elastic deformation is possible at the portion facing the recording material 3, and the transfer efficiency is improved. It should be noted that the conductivity here may be sufficient as long as the toner image on the image carrier 1 is electrostatically transferred to the intermediate transfer member 2 as described above.
Furthermore, the holding layer 2a disposed on the outer surface of the intermediate transfer member 2 is composed of a far-infrared absorbing member, so that the heat from the heating means 4 is effectively absorbed, and the energy efficiency with respect to the heating is increased. Is further improved. At this time, examples of the far-infrared absorbing member include an insulating member to which a far-infrared absorbing radiation material such as ceramics is added. The holding layer 2a may be either rigid or elastic, but a rigid member is preferable from the viewpoint of suppressing elongation during transfer and suppressing color unevenness. Further, the insulating member of the holding layer 2a only needs to have an insulating property that can transfer and hold the toner image formed on the image carrier 1.

  The heating unit 4 includes a non-contact heating source disposed opposite to the outside of the intermediate transfer body 2 so that far infrared rays (including infrared rays) emitted from the heating source are absorbed by the holding layer 2a. Easier and more energy efficient. Further, by providing the heating means 4 outside the intermediate transfer member 2, the apparatus can be miniaturized. If it is assumed that the heating means 4 is provided inside the intermediate transfer member 2, the structure becomes complicated, the heating energy is required to be large, and the apparatus may be increased in size.

Further, in the present invention, it is preferable that the axial length of the image carrier 1 is shorter than that of the intermediate transfer member 2, so that the heat insulating layer 2 b of the intermediate transfer member 2 is deformed in the axial direction of the image carrier 1. Thus, the transfer from the image carrier 1 to the intermediate transfer member 2 is uniformly performed in the axial direction.
According to such an embodiment, the heat applied to the holding layer 2a of the intermediate transfer body 2 can be concentrated mainly only on the holding layer 2a, and the heating for melting the toner image on the intermediate transfer body 2 can be reduced. As a result, energy efficiency is improved.
Further, as an aspect of the intermediate transfer member 2 according to the present invention, an intermediate transfer member 2 interposed between the image carrier 1 and the recording material 3 and transferring a toner image on the image carrier 1 to the recording material 3 It is characterized in that at least one layer is constituted by a multilayer structure which is a heat insulating layer 2b containing a gas in a ratio of 30% or more by volume.

  According to the present invention, in the image forming apparatus of the type in which the molten toner is transferred and fixed to the recording material, the intermediate transfer member is constituted by a multilayer structure in which at least one layer is a heat insulating layer containing a gas. Energy consumption during heating and melting is greatly reduced.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 is an explanatory diagram showing Embodiment 1 of a tandem type image forming apparatus to which the present invention is applied. The image forming apparatus in the figure forms a color image on a sheet 46 as a recording material. For example, each color component (for example, yellow (Y), magenta (M), cyan (C), An image forming unit 10 (specifically, 10a to 10d) on which a black (K) toner image is formed is disposed, and the image forming unit 10 is disposed in parallel with the sheet conveying belt 40.
Here, the image forming unit 10 used in this embodiment includes a photosensitive drum 11 that forms and supports each color component toner image, and the toner image on the photosensitive drum 11 is transferred so as to be opposed to the photosensitive drum 11. The intermediate transfer roll 20 thus carried, and the transfer roll 29 for transferring and fixing the heat-melted toner image on the intermediate transfer roll 20 onto a sheet 46 as a recording material on the sheet conveying belt 40. Yes. In this embodiment, the axial length of the intermediate transfer roll 20 is set to be longer than the axial lengths of the photosensitive drum 11 and the transfer roll 29.

In the present embodiment, an electrostatic latent image is formed on the charged photosensitive drum 11 around the photosensitive drum 11 rotating in the direction of arrow A, such as a charger 12 such as a charging roll for charging the photosensitive drum 11. An exposure device 13 composed of a semiconductor laser for writing, a developing device 14 that visualizes the electrostatic latent image formed on the photosensitive drum 11 with each color component toner, and a cleaning blade that cleans residual toner on the photosensitive drum 11 15 is disposed.
Further, around the intermediate transfer roll 20 rotating in the direction of arrow B, as a heating means (not shown) for heating and melting the toner image on the intermediate transfer roll 20, for example, a far infrared heater (shown in FIG. 4). Is disposed upstream of the position where the intermediate transfer roll 20 and the transfer roll 29 face each other, and is configured to heat the intermediate transfer roll 20. Reference numeral 30 denotes a cleaning device that cleans residual toner on the intermediate transfer roll 20.

  On the other hand, the sheet conveying belt 40 in the present embodiment is stretched around a plurality of stretching rolls 41 to 43, and is configured to be rotatable with the stretching roll 41 as a driving roll, for example, so as to move in the direction of arrow C. It is configured. Further, on the upstream side of the position where the image forming unit 10a of the sheet conveying belt 40 is disposed, a charger 44 made of corotron or the like for adsorbing the sheet 46 to the sheet conveying belt 40 is disposed. A predetermined charge is applied to 40 so that the sheet 46 can be adsorbed. In order to secure the charging performance of the charger 44, a backup roll 45 is provided at a position facing the charger 44 with the sheet conveying belt 40 therebetween.

Here, the intermediate transfer roll 20 in the present embodiment will be described in detail with reference to FIGS. 3A is a structural diagram of the intermediate transfer roll 20, and FIG. 3B is an enlarged sectional view of FIG.
The intermediate transfer roll 20 according to the present embodiment has a configuration in which, for example, a silicone rubber elastic layer 23 subjected to resistance adjustment is coated on a metal core 24 such as aluminum as a semiconductive elastic body. Between the outermost holding layer 21 made of a resin layer or the like, an air layer 22b is formed as a heat insulating layer 22 sealed at both ends with elastic ribs 22a (produced simultaneously with the elastic layer 23 in the present embodiment). ing.

Next, the operation of the image forming apparatus according to the present embodiment will be described with reference to FIGS.
In the present embodiment, the toner image formed on the photosensitive drum 11 is transferred to the intermediate transfer roll 20 side by a primary transfer bias (not shown) at a portion where the photosensitive drum 11 and the intermediate transfer roll 20 face each other. . The toner image transferred to the intermediate transfer roll 20 is heated and melted, and transferred and fixed on the sheet 46 conveyed on the sheet conveyance belt 40 at a portion where the intermediate transfer roll 20 and the transfer roll 29 face each other. . The sheet 46 that has been transferred by each of the image forming units 10 (10a to 10d) is separated from the sheet conveying belt 40 at the stretching roll 42 and is conveyed to, for example, a discharge tray (not shown).

Here, the transfer process from the photosensitive drum 11 to the intermediate transfer roll 20 and the transfer process from the intermediate transfer roll 20 to the sheet 46 will be described in detail with reference to FIG.
In the transfer nip region (D region) between the photosensitive drum 11 and the intermediate transfer roll 20, the heat insulating layer 22 made of the air layer 22 b is compressed and applied between the metal core 24 and the photosensitive drum 11 (not shown). The transfer bias acts effectively, and the toner image formed on the photosensitive drum 11 is transferred (primary transfer) onto the intermediate transfer roll 20.
The toner transferred onto the intermediate transfer roll 20 is heated by a far infrared heater 28 disposed so as to face the intermediate transfer roll 20. At this time, the far-infrared heater 28 can effectively heat the intermediate transfer roll 20 because the radiation from the heater 28a is effectively directed to the intermediate transfer roll 20 side by the reflector 28b.
By this heating, both the holding layer 21 on the surface of the intermediate transfer roll 20 and the toner transferred onto the holding layer 21 are heated, so that only the toner is melted.
When the melted toner reaches the subsequent transfer nip region (E region), the toner is transferred onto the sheet 46 conveyed on the sheet conveying belt 40. At this time, the heat transfer layer 22 of the intermediate transfer roll 20 is compressed by the pressure contact between the intermediate transfer roll 20 and the transfer roll 29, and the load from the metal core 24 on the intermediate transfer roll 20 side is effectively transferred through the elastic layer 23. Thus, the toner is transferred onto the sheet 46 with certainty.
Therefore, in the present embodiment, when the toner on the intermediate transfer roll 20 is heated, only the holding layer 21 can be effectively heated, and the heating energy for melting the toner is reduced.

In the present embodiment, the air layer 22b is used as the heat insulating layer 22. However, for example, a foam made of SR conductive sponge sheet manufactured by Tigers Polymer Co., Ltd. can be used. Features can be used, and the same effects as when the air layer 22b is used can be obtained. The foam may be open-celled or closed-celled, but the closed-cell type is preferred from the standpoint of heat resistance and uniformity of pressure change.
Further, although the silicone-modified acrylic resin is used as the holding layer 21, the present invention is not limited to this, and the toner image from the photosensitive drum 11 can withstand the heating from the heating source (in this embodiment, the far infrared heater 28 is used). Any insulating material that can be transferred may be used. For example, a polyimide film may be used.
Further, in the present embodiment, the mode in which the elastic layer 23 is provided in the lower layer of the heat insulating layer 22 is shown. However, for example, the metal core 24 reaches the elastic layer 23 without the elastic layer 23. In this case, since the holding layer 21 has elasticity, the same operation in the transfer nip region described above can be performed.

In this example, in an image forming apparatus having the same configuration as that of the first embodiment, three types of intermediate transfer rolls were used, and as an evaluation related to the heat capacity of the intermediate transfer roll, the transfer performance to the sheet and the photosensitive drum The toner adhesion to the toner was evaluated and confirmed.
As an intermediate transfer roll used in this example, an aluminum core having a diameter of 50 mm and a thickness of 3 mm was used, and a semiconductive elastic body having a thickness of 5 mm, a JIS-A hardness of 10 degrees, and a volume resistivity of 3 log Ω · cm. The silicone rubber was coated with (when 100 V was applied), and a silicone-modified acrylic resin having a thickness of 10 μm and a volume resistivity of 12 logΩ · cm was used as the surface layer. And as a heat insulation layer, it compared with the following three types (a)-(c).
(A) A heat-resistant foam (SR conductive sponge sheet manufactured by Tigers Polymer Co., Ltd.) having a thickness of 2 mm, a volume resistivity of 4 logΩ · cm (test method SRIS2301 voltage-current method) and a foaming ratio of 3 times was used. Here, the expansion ratio indicates a value obtained by dividing the raw resin density by the foam density.
(B) One having ribs (height 3 mm, width 5 mm) formed by integral molding with the same silicone rubber at both ends of the elastic body was used.
(C) As a comparative example, a heat insulating layer made of a thick silicone rubber (5 mm to 7 mm) was used.
In the evaluation in this example, A4 size Fuji Xerox Co., Ltd. JC paper was used as a sheet, and 100 sheets of continuous printing were performed with Fuji Xerox Co., Ltd. DocuCentre Color 500 toner. The process speed was 351 mm / sec, and the input power to the heating source in (a) and (b) was the power at which the four color toners (toner amount 17 mg / m ² ) were melted.
The result of this example is as shown in FIG.
That is, in the intermediate transfer rolls (a) and (b), the transfer from the first sheet to the sheet is good and the toner does not adhere to the photosensitive drum.
On the other hand, as a comparative example, in the intermediate transfer roll (c) having no heat insulating layer, the toner is insufficiently melted in the first transfer even when an upper limit of 6 kW is applied to the power supply (200 V, 30 A) that can be normally used. Therefore, transfer failure occurred. On the 100th sheet, since the temperature of the intermediate transfer roll increased, the temperature of the photosensitive drum also increased, and toner fixation on the photosensitive drum occurred. Further, in this (c), when the process speed is slowed down and the condition under which transfer failure does not occur from the first sheet is 10-15 mm / sec, it is not applicable in terms of toner fixing to the photosensitive drum. .
As described above, the effectiveness of the present invention was confirmed in this example.

(A) (b) is explanatory drawing which shows the outline | summary of the image forming apparatus to which this invention was applied. 1 is an explanatory diagram illustrating an image forming apparatus according to Embodiment 1. FIG. (A) and (b) are the principal part enlarged views of Embodiment 1. FIG. FIG. 3 is an explanatory diagram showing the operation of the first embodiment. It is explanatory drawing which shows the result of an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Intermediate transfer body, 2a ... Holding layer, 2b ... Heat insulation layer, 2c ... Elastic layer, 3 ... Recording material, 4 ... Heating means

Claims (9)

In an image forming apparatus of a type in which a toner image formed on an image carrier is transferred to an intermediate transfer member, and the toner image on the intermediate transfer member is transferred onto a recording material.
The image forming apparatus, wherein the intermediate transfer member has a multilayer structure in which at least one layer is a heat insulating layer containing a gas at a volume ratio of 30% or more. The image forming apparatus according to claim 1.
An image forming apparatus comprising heating means for heating and melting the toner image when transferring the toner image on the intermediate transfer member onto a recording material. The image forming apparatus according to claim 1 or 2,
The image forming apparatus, wherein the heat insulating layer is a hollow layer in which a gap between both ends of the heat insulating layer is sealed with a sealing body. The image forming apparatus according to claim 1 or 2,
The image forming apparatus, wherein the heat insulating layer is made of a conductive foam. The image forming apparatus according to claim 1 or 2,
An image forming apparatus comprising an elastic layer made of a conductive elastic body under a heat insulating layer of an intermediate transfer member. The image forming apparatus according to claim 1 or 2,
An image forming apparatus comprising a holding layer configured to include a far infrared ray absorbing member and holding a toner image on an outer surface of an intermediate transfer member. The image forming apparatus according to claim 2.
The image forming apparatus, wherein the heating unit includes a non-contact heating source disposed to face the intermediate transfer member. The image forming apparatus according to claim 1 or 2,
An image forming apparatus characterized in that the axial length of the image carrier is shorter than the axial length of the intermediate transfer member. In an intermediate transfer member that is interposed between the image carrier and the recording material and transfers the toner image on the image carrier to the recording material,
An intermediate transfer member comprising a multilayer structure in which at least one layer is a heat insulating layer containing a gas at a volume ratio of 30% or more.

Images