JP3330747B2 - Fixing device cleaning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device cleaning device.

[0002]

2. Description of the Related Art A cleaning device for a fixing device including a cleaning roller in contact with a fixing roller facing at least a toner carrying surface of a thermal fixing roller pair and a backup roller in contact with the cleaning roller is known. In such a conventional cleaning device, a means for preventing a so-called offset phenomenon in which dirt on the fixing roller is reversely transferred to the transfer paper is taken, and examples thereof include the following technology.

[0003] In order to reliably prevent toner from adhering to the fixing roller, the fixing roller, the first and the second cleaning rollers are contacted and separated from each other in this order, the releasability and the temperature are set lower in this order, and A device having a surface temperature lower than the melting point of toner (Japanese Patent Laid-Open No. 61-86776).
Reference).

[0004] In order to prevent offset from the fixing roller, the surfaces of the fixing roller and the cleaning roller are formed of the same material in terms of releasability (Japanese Patent Laid-Open No. 61-22 / 1986).
No. 1773).

[0005]

In the conventional cleaning device, the effect of preventing the offset is still insufficient, and it is difficult to eliminate the offset at the time of starting.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device cleaning device capable of exhibiting a sufficient offset prevention effect.

[0007]

In order to achieve the above object, the present invention is configured as follows. (1). A cleaning device for a fixing device, comprising: a cleaning roller in contact with a fixing roller facing at least a toner carrying surface of a pair of thermal fixing rollers; and a backup roller in contact with the cleaning roller, wherein the cleaning roller is formed of conductive rubber, Contact and separation of the roller to and away from the cleaning roller
Means and temperature detecting means for detecting the temperature of the fixing roller
Provided that the temperature of the fixing roller is lower than room temperature.
The temperature of the fixing roller is room temperature because reverse transfer is easy under
The backup roller until the
Separated from the running roller, the temperature of the fixing roller is reversed
Once the backup row has been restored to the extent that
By pressing the roller against the cleaning roller,
The cleaning roller is cleaned by the backup roller.
It was decided to make the training (claim 1).

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[Function] When the temperature of the fixing roller is lower than room temperature
Is easy to reverse transfer, so the fixing roller temperature is lower than room temperature.
Clean the backup roller until it comes up
Keep away from

[0014]

【Example】

(I) Description of Copying Machine Suitable for Implementing the Present Invention The copying machine shown in FIG. 6 includes an apparatus main body 1 and an automatic document feeder (Double Jo) mounted on an upper part of the apparatus main body.
b Feeder, hereinafter referred to as DJF. 2), and an image is formed by the image forming device 7 on the upper surface of the transfer paper P fed from the paper feeding device 3 via the conveyance path 9.

In the apparatus main body 1, a contact glass 61 constituting the exposure device 6 is disposed on the upper surface, and a first scanning system 62 including a light source and a mirror and a second scanning system 63 including a mirror are disposed immediately below the contact glass 61. Place each. Further, a photosensitive drum 70,
Charger 71, eraser 72, developing unit 7
4. The image forming apparatus 7 including the transfer unit 77, the cleaning unit 76, and the fixing device 78 is provided.

The paper feeding device 3 includes paper feeding trays 31A, 31
B, 31C, 31D and a manual feed tray 4,
Unused transfer paper P is selectively fed from one of these paper feed trays to the image forming apparatus 7 by a paper feed roller or the like.
Below the image forming device 7, a double-sided tray 8 for performing double-sided copying is arranged.

Next, the process of making a copy by the copying machine will be briefly described. As shown in FIG. 6, the base paper D set on the DJF 2 with the image surface facing upward is sent to the left from the first sheet on the lower side (final page), turned downward, and sent on the contact glass 61. Then, it is stopped at a predetermined exposure position. Subsequently, the image of the document D is projected onto the photosensitive drum 70 via the lens 64, mirrors 65, 66, and the like by the exposure device 6 (exposure step). Body drum 7
0, an electrostatic latent image is formed on the surface.

The electrostatic latent image on the photoreceptor drum 70 is erased from the non-image area by an eraser 72, and then a toner is adhered by a developing unit 74 to form a visible image.
This visible image is stored in each of the paper feed trays 31A, 31A of the paper feed device 3.
A, 31B, 31C, 31D and the transfer unit 77 on the upper surface of the transfer paper P fed from any of the manual feed tray 4.
, And is heated and fixed by the fixing device 78, and is discharged onto the paper discharge tray 79.

The toner slightly remaining on the photosensitive drum 70 is cleaned by the cleaning unit 76 to prepare for the next image formation.

[0020] (ii) onset illustration 1 on the fixing roller 81 to form a heat fixing roller pair shows an embodiment of a fixing device provided with a cleaning device according to the present invention corresponding to the bright, the lower fixing roller 82 Of which, the upper fixing roller 81
Is a heat roller incorporating a heater 86.

The lower fixing roller 82 is pressed against the upper fixing roller 81, and the upper fixing roller 81
The toner image on the transfer paper P sent with the toner carrying surface upward between the lower fixing rollers 82 is pressed and thermally fixed. Therefore, the toner carrying surface comes into contact with the upper fixing roller 81 to perform the fixing, and the toner, the paper dust and the like adhere.

The upper fixing roller 81 is made of an aluminum cored bar 8.
The lower fixing roller 82 is formed by covering an aluminum cored bar 82a with a rubber layer 82b made of silicon rubber. Further, a thermistor 85 is provided on the surface of the upper fixing roller 81.
Is applied, the power supply to the heater 86 is controlled in accordance with the surface temperature of the upper fixing roller 81, and a predetermined fixing temperature is maintained.

A cleaning roller 83 is pressed against the upper fixing roller 81, and a backup roller 84 is pressed against the cleaning roller 83.

Both the fluororesin layer 81b of the upper fixing roller 81 and the rubber layer 82b of the lower fixing roller 82 exhibit excellent releasability, but the offset phenomenon cannot be completely prevented.

Therefore, in this embodiment, the cleaning roller 8
The material of No. 3 was conductive rubber. In the fixing process, the upper fixing roller 81 rotates, and charges are gradually accumulated by frictional charging. In this embodiment in which the cleaning roller 83 is made of conductive rubber,
Does not rise higher than the upper fixing roller 81, so that toner and paper dust adhering to the upper fixing roller 81 during fixing are transferred to the cleaning roller 83 side satisfactorily due to the potential difference between these two rollers, and the cleaning effect is improved. Is improved. As a result, the offset phenomenon from the upper fixing roller 81 to the transfer paper is greatly reduced as compared with the related art.

Since the material of the cleaning roller 83 is conductive rubber, toner and paper powder can be made to adhere to the cleaning roller by the potential difference.

[0027] In illustration 2 corresponding to (iii) onset Akira shows a cleaning roller according to the present embodiment by reference numeral 83 b. Other configurations are the same as those shown in FIG. The main body 83b-1 of the cylindrical roller constituting the cleaning roller 83b is made of conductive rubber as in the embodiment shown in FIG. 1 in (ii).

The main body 83b-1 is covered with a cylindrical body 83b-2 made of a non-conductive material having good releasability. As the cylindrical body 83b-2, a tube made of a fluororesin is used.

In this embodiment, the roller body 83-b
Is electrically conductive, the potential becomes low in relation to the upper fixing roller 81 as in the example in (ii) above, and the toner and paper powder attached to the upper fixing roller 81 are favorably transferred due to the potential difference. Further, the cylindrical body 83b covering the surface
2 has good releasability, so that the transferred toner and paper dust can be more easily removed than in the embodiment described in (i) above. As a result, the reverse rotation from the cleaning roller 83b to the upper fixing roller 81 can be performed. Photocopying can be prevented.

Since the conductive rubber constituting the cleaning roller is provided with a non-conductive coating film such as a PFA tube, which is highly releasable, the reverse transfer from the backup roller 84 to the upper fixing roller 81 can be performed. Thus, the life of the cleaning roller can be prolonged.

[0031] In illustration 3 corresponding to (iv) onset Akira shows such cleaning roller in this embodiment by reference numeral 83c. Other configurations are the same as those shown in FIG. The main body 83c-1 of the cylindrical roller constituting the cleaning roller 83c is made of conductive rubber as in the embodiment shown in FIG. 1 in (ii).

The main body 83c-1 is covered with a cylindrical body 83c-2 made of a conductive material having good releasability. In order to satisfy the conductivity and the releasability, the cylindrical body 8
As 3c-2, a tube made of fluorocarbon resin containing carbon particles is used.

In this embodiment, since the entire cleaning roller becomes conductive, the transfer of toner and paper powder is obtained, and the cleaning performance is excellent, as in the case of the above (ii). Then, the cylindrical body 83c covering the surface
2 has good releasability, so that the transferred toner and paper dust can be easily removed.
Reverse transfer from 3b to the upper fixing roller 81 can be prevented.

Since the conductive rubber constituting the cleaning roller is provided with a conductive and highly releasable coating film on the surface thereof, the electric characteristics of the cleaning roller are improved, the cleaning property is improved, and the offset is improved. Is prevented.

[0035] (v) The present example corresponds to the onset Ming is applicable to the cleaning roller in the (ii) ~ (iv). Therefore, in FIGS. 4 and 5 which describe the embodiment, the cleaning roller in the present embodiment is denoted by reference numeral [83] in a sense representing the respective cleaning rollers. The relationship between the upper fixing roller 81 and the lower fixing roller 82 is the same as the configuration in FIG.

In FIG. 4, the cleaning roller [8
In [3], the backup roller 84 is in pressure contact. This pressure contact is performed by the contact / separation means according to the present embodiment. The configuration of the contact / separation means will be described. The other end of the support member 87 that supports the backup roller 84 at one end thereof is supported by a stationary member (not shown) with a shaft 88.

An intermediate portion of the support member 87 is hung on the other end side of an elastic spring 860 with one end hung on a stationary member, and the support member 87 is pulled by the spring 860. The support member 8 on which the spring 860 is hung
A plunger 850a of a solenoid 850 fixed to an immovable member is connected to an intermediate portion of the seventh. In addition, the solenoid 850 is swingably attached to the immovable member by the pin 850b. In the present example, the contacting / separating means is mainly composed of the support member 88, the solenoid 850, the spring 860, and the like.

In the state shown in FIG. 1, the solenoid 850 is off, whereby the force of the spring 860 directly acts on the support member 87, and the backup roller 840 is pressed against the cleaning roller [83]. It is.

When the solenoid 850 is turned on, as shown in FIG. 5, the plunger 850a pulls the support member 87, and the backup roller 840 is separated from the cleaning roller [83].

In this embodiment, since the backup roller 840 can be moved toward and away from the cleaning roller [83] by the contact / separation means, the copying machine enters a driving state from a stopped state. When the temperature of the upper fixing roller 81 is low when the fixing device rises, if the backup roller 840 is kept in pressure contact with the cleaning roller [83], the toner adhering to the backup roller 840 is cleaned. The reverse transfer is performed to the roller [83], and further the reverse transfer is performed to the upper fixing roller 81. As a result, the offset cannot be prevented.

Therefore, in this embodiment, under such circumstances, the offset is prevented by driving the contact / separation means. When the temperature of the upper fixing roller 81 has recovered to the extent that the reverse transfer does not occur, the contact / separation means is driven to turn the backup roller 840 into a cleaning roller [83].
To perform the cleaning function of the cleaning roller [83]. Also, the pressure of the backup roller 840 causes the backup roller 84 to be pressed.
The cleaning of the cleaning roller [83] by 0 is also performed.

In this embodiment, since the backup roller can be moved toward and away from the cleaning roller, it is possible to prevent reverse transfer from the backup roller when the temperature of the upper fixing roller is low, such as at the first rising in the morning. .

(Vi) Description Corresponding to the Invention of Claim 1 In the embodiment described in (v), the upper fixing roller 8
If the backup roller 840 is kept pressed against the cleaning roller [83] in a state where the temperature of the first fixing roller 1 is low, the toner adhering to the backup roller 840 is reversely transferred to the cleaning roller [83], and further, the upper fixing roller It has been explained that the reverse transfer to the image 81 results in that the offset cannot be prevented after all.

In order to effectively cope with such a situation, in this embodiment, as shown in FIGS. 4 and 5, the temperature of the upper fixing roller 81 is detected by a thermistor 85, and based on the detection result, for example, the upper fixing roller 81 is detected. When the temperature of the backup roller 81 is lower than room temperature, the toner of the backup roller 840 is likely to be reversely transferred to the cleaning roller [83]. 83]. This control is performed by thermistor 8
5 and the contact / separation means described in the embodiment (v).

In this embodiment, the backup roller is brought into contact with or separated from the cleaning roller depending on the temperature of the upper fixing roller detected by the thermistor or other temperature detecting means. Can be eliminated in control, and offset can be prevented.

[0046]

According to the present invention, it is possible to provide a cleaning device for a fixing device capable of exhibiting a sufficient offset preventing effect.

[Brief description of the drawings]

FIG. 1 is a front view showing a cleaning device according to an embodiment of the present invention together with a fixing device.

FIG. 2 is a front view of the cleaning device illustrating one embodiment of the present invention.

FIG. 3 is a front view of the cleaning device illustrating one embodiment of the present invention.

FIG. 4 is a diagram illustrating a state in which a backup roller is separated from a cleaning roller by a contacting / separating unit according to the present invention.

FIG. 5 is a diagram illustrating a state in which a backup roller is brought into pressure contact with a cleaning roller by a contact / separation unit according to the present invention.

FIG. 6 is a front view of a copying machine embodying the present invention.

[Explanation of symbols]

 83 Cleaning roller

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-89979 (JP, A) JP-A-61-193169 (JP, A) JP-A-2-40683 (JP, A) JP-A-61-193 221773 (JP, A) JP-A-63-300272 (JP, A) JP-A-64-66676 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/10-21 / 12 G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] 1. A cleaning device for a fixing device, comprising: a cleaning roller in contact with a fixing roller facing at least a toner carrying surface of a thermal fixing roller pair; and a backup roller in contact with the cleaning roller, wherein the cleaning roller is made of conductive rubber. A contact / separation unit for contacting / separating the backup roller from / to the cleaning roller, and a temperature for detecting a temperature of the fixing roller.
Temperature detecting means, the temperature of the fixing roller is lower than room temperature.
Reverse transfer is easy under low conditions, so the fixing roller
Roll the backup roller until the temperature rises above room temperature
Separated from the cleaning roller, the temperature of the fixing roller was restored to a level that does not cause reverse transfer.
If the backup roller is a cleaning roller
By pressing against the backup roller
A fixing device cleaning device for cleaning the cleaning roller .