JPH0572938A - Fixing device for image forming device - Google Patents

Abstract

PURPOSE:To stabilize fixing and to improve durability of a pressure roller by providing a means which is actuated by interlocking with the ON/OFF action of a power source switch and which releases the press-contacting between the pressure roller and a heating roller when the power source is turned off. CONSTITUTION:When printing work is not executed for a long time, the knob 51 of a power source switch 50 is turned and positioned on an OFF position P2, a rotary shaft 52 is rotated, a contact terminal 53 is separated from a contact 59 on a primary side, and the power source is turned off. In this case, the plate 41 of an interlocking means 40 is turned downward by interlocking with the OFF action of the power source switch 50, and a link 21 is turned counterclockwise as shown by a figure centered on the shaft center of a connecting shaft 29. At the same time, the link of a frame on the other side is similarly turned through the connecting shaft 29. Thus, the pressure roller 13 is separated from a heating roller 11 by resisting the elastic force of a spring 14 through each long hole part 23, etc., of the link 21, etc., so that a press- contacting state is released. Thus, the pressure roller 13 is released from the influence of the heating roller 11 while stopping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus.

[0002]

2. Description of the Related Art FIG. 6 shows a schematic structure of a conventional image forming apparatus.

In the figure, reference numeral 1 is an apparatus main body. An image carrier 2, a charging device 3, a scanner unit 4, a developing device 7, a transfer device 8, a paper feeding section 9, a fixing device 10A and the like are arranged in the main body 1 of the apparatus.

When printing is performed using this image forming apparatus, the peripheral surface of the image carrier 2 is charged by the charging device 3,
The scanner unit 4 irradiates the peripheral surface with a laser beam based on image information to form an electrostatic latent image. The electrostatic latent image is developed into a toner image by the developing device 7 and then transferred onto the transfer material P sent from the paper feeding unit 9 by the transfer device 8. Then, the unfixed toner image transferred onto the transfer material P is heated and fixed by the fixing device 10A.

Here, the conventional fixing device 10A includes a cylindrical heating roller 11 that is rotationally driven in the paper feeding direction (the direction of the arrow in the figure), and a heating member (for example, a halogen lamp 12) that heats the heating roller 11. , A pressure roller 13 that presses the transfer material P that is rotated and sent in contact with the heating roller 11 by the elastic force of a spring, and a temperature detection element that detects the surface temperature of the heating roller 11 ( (Not shown) and a temperature control device (not shown) that controls the operation of the heating member (12) based on a detection signal from the temperature detection element to set the surface temperature of the heating roller 11 to a set temperature (for example, 170 ° C.). It is generally configured to include.

The heating roller 11 is usually made of an aluminum or stainless steel cored bar coated with a non-adhesive and heat-resistant resin such as ethylene tetrafluoride in an amount of 20 to 50 μm. In addition, the pressure roller 13
As the material, a non-adhesive and heat-resistant elastic material such as silicone rubber is usually used.

[0007]

By the way, in the above-mentioned image forming apparatus, the heating roller of the fixing device 10A is used not only when the printing operation is being performed but also when the printing operation is not performed for a long time and the rotation is stopped. 11 and pressure roller 1
No. 3 is in pressure contact. Therefore, the peripheral surface portion of the pressure roller 13 that is in pressure contact with the heating roller 11 easily exceeds the allowable limit and is locally deformed, and the sheet cannot be uniformly pressed against the heating roller 11 during the fixing operation, resulting in uneven fixing. Poor fixing may occur. Further, since the pressure roller 13 is constantly subjected to a considerable amount of stress, its life tends to be shortened, and it is difficult to improve durability.

In view of the above circumstances, an object of the present invention is to provide a fixing device of an image forming apparatus which can stabilize the fixing property and improve the durability of the pressure roller.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to an image forming apparatus having a heating roller which has a heating member built therein and is driven to rotate in the sheet feeding direction, and a pressure roller which is rotated while being in pressure contact with the heating roller. In the fixing device of the above, the power is turned off by being operated in conjunction with the ON / OFF operation of the power switch.
It is characterized in that a pressure contact releasing means for releasing pressure contact between the pressure roller and the heating roller when the pressure is applied is provided.

[0010]

According to the present invention, when the power switch is turned off, the pressure contact releasing means is operated in conjunction with this to release the pressure contact between the pressure roller and the heating roller. As a result, the pressure roller is prevented from being locally deformed beyond the allowable limit by being pushed by the heating roller when the rotation is stopped, and the peripheral surface of the roller is maintained in a smooth state.

Therefore, at the time of printing operation, the transfer material on which the unfixed toner image is transferred can be pressed against the heating roller with a uniform force by using the pressure roller, and the fixing property can be stabilized. Also, since the pressure roller is released from the state in which a considerable amount of stress is released by releasing the pressure contact,
The life can be extended and the durability can be improved. further,
Since the pressure contact state of both rollers is released in conjunction with the turning-off operation of the power switch, erroneous operation is prevented and the handleability is improved.

[0012]

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

As shown in FIGS. 1, 3, and 5, the fixing device of the image forming apparatus according to this embodiment includes a heating roller 11, a heating member (a halogen lamp 12 in this embodiment), and a pressure roller 1.
3, a spring 14, frames 15a and 15b, a temperature detecting element, a temperature control device, and a pressure contact releasing means 20 which is a characteristic part of this device.

The same components as those shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted or simplified.

In this embodiment, the heating roller 11 is rotatably supported between the frames 15a, 15a as shown in FIG. Further, as shown in FIG. 1, the pressure roller 13 is configured to rotate while being in pressure contact with the heating roller 11 via the bearing 16 and the spring 14.

The pressure contact releasing means 20 is composed of the heating roller 1.
It is a means for releasing the pressure contact between 1 and the pressure roller 13.

Specifically, the pressure contact releasing means 20 is connected to the power switch 5 by the interlocking means 40 in order to prevent erroneous operation.
The heating roller 11 and the pressure roller 13 are released from the pressure contact with each other when the power switch 50 is turned off by being operated in conjunction with the ON / OFF operation of 0.

First, the structure of the power switch 50 will be described.

The power switch 50 is of a rotary type and, as shown in FIG. 1, is composed of a rounded grooved portion 51, a rotary shaft 52, a connection terminal 53 and the like. This cutting part 5
1 is rotatably provided on the apparatus main body 1 via a rotary shaft 52. On the rotary shaft 52, contact terminals 53, 5 for connecting / disconnecting contact parts (primary contact parts) 59, 59 of the primary side electric circuit to turn on / off the circuit.
3 is provided. Then, when the squeezing portion 51 is appropriately rotated and positioned at the ON position P1 shown in FIG. 1, the contact terminals 53, 53 are brought into close contact with the primary side contact portions 59, 59 to conduct electricity. In addition, as shown in FIG.
When positioned at the OFF position P2, the contact terminals 53, 53
Is separated from the primary side contact parts 59, 59, and electrical conduction is lost.

In this embodiment, the pressure contact releasing means 20 has a link structure, and includes links 21, 31 and a connecting shaft 29 as shown in FIG.

Each of the links 21 and 31 has a frame 1
5a and 15b are rotatably provided via a connecting shaft 29. The links 21 and 31 have elongated holes 23 and
33 is provided, and the shaft portions 13a and 13b on both sides of the pressure roller 13 are slidably fitted into the elongated hole portions 23 and 33, respectively. Therefore, when the link 21 is rotated counterclockwise in the figure from the position shown in FIG. 1, the pressure roller 13 causes the elongated hole portion 23, the shaft portion 13a and the connecting shaft 2 to rotate.
9, heating roller 1 through slot 33 and shaft 13b
It is separated from 1 and pressure contact is released.

The interlocking means 40 is the interlocking plate 4
1 and the stud 42 and the like. The interlocking plate 41 is fixed to the end of the rotary shaft 52 of the power switch 50. A stud 42 is provided on the interlocking plate 41 at a predetermined distance from the rotating shaft 52. The stud 42 is slidably fitted in the elongated hole portion 24 of the link 21 of the pressure contact releasing means 20.

Next, the operation will be described.

In the above-mentioned image forming apparatus, when the printing operation is not performed for a long time, as shown in FIG. 2, the gripping portion 51 of the power switch 50 is turned to the OFF position P2. Then, the rotary shaft 52 rotates and the contact terminal 5
3, 53 separates from the primary side contact parts 59, 59 and the power is turned off.
To be done.

On the other hand, the power switch 50 is turned off.
In conjunction with the operation, the interlocking plate 41 of the interlocking means 40 rotates downward, and pushes down the elongated hole portion 24 of the link 21 via the stud 42. As a result, the link 21 becomes the connecting shaft 2.
It rotates in the counterclockwise direction in FIG. 2 about the axis of the shaft 9. At the same time, the link 31 shown in FIG.
It is moved downward via and is rotated in the same direction as the link 21 by the same angle amount. As a result, the pressure roller 13 is separated from the heating roller 11 against the elastic force of the spring 14 through the elongated holes 23 and 33 of the links 21 and 31, and the pressure contact state is released.

As a result, the pressure roller 13 is prevented from being locally deformed beyond the allowable limit by being pushed by the heating roller 11 when the rotation is stopped, and the peripheral surface of the roller 13 is maintained in a smooth state. Therefore, during the printing operation, the transfer material P onto which the unfixed toner image is transferred can be pressed against the heating roller 11 by the pressure roller 13 with a uniform force, and the fixing property can be stabilized. Further, since the pressure roller 13 is released from the state in which a considerable amount of stress is applied by releasing the pressure contact, the life is extended.

On the other hand, when the power is turned on, as shown in FIG. 1, the squeezing portion 51 of the power switch 50 is set to the ON position P1.
By positioning the connection terminals 53, 53 to 1
It is in close contact with the secondary side contact parts 59, 59. As a result, the primary side contact parts 59, 59 are conducted and electricity is supplied.

In conjunction with the ON operation of the power switch 50, the interlocking plate 41 of the interlocking means 40 pivots upward and pushes up the elongated hole portion 24 of the link 21 via the stud 42. At the same time, the link 31 also rotates via the connecting shaft 29 in the same direction as the link 21 by the same angle amount.
As a result, the pressure roller 13 is pressed by the heating roller 11 while following the elastic force of the spring 14.

According to this embodiment, however, the heating roller 11 and the pressure roller 13 are released from the pressure contact state when they are operated in conjunction with the ON / OFF operation of the power switch 50 and the switch 50 is turned off. Pressure contact releasing means 20
The pressure contact releasing means 20 is operated to release the heating roller 11 and the pressure roller 13 from the pressure contact state when the power is turned off (when the printing operation is stopped). As a result, local deformation of the pressure roller 13 can be prevented and the fixability can be stabilized. Also, the durability can be improved.

Further, since the pressure contact releasing means 20 is operated in conjunction with the ON / OFF operation of the power switch 50, erroneous operation can be effectively prevented.

Further, since the pressure contact releasing means 20 is a link mechanism, the structure is simplified and repairs and the like can be easily performed. Further, the heating roller 11 and the pressure roller 13 can be reliably released from the pressed state.

In the above embodiment, the pressure contact releasing means 20
ON / O of the power switch 50 by using the interlocking means 40.
Although it is configured to operate in conjunction with the FF operation, it may be configured to operate in conjunction with the power switch 50 without using the interlocking means 40.

For example, as shown in FIG. 4, the pressure contact releasing means 2
The power switch 50 is turned on / off at one end of the 0 link 21.
A solenoid 61 that is driven / stopped in conjunction with the OFF operation is connected, and the solenoid 21 is used to link 21.
May be rotated counterclockwise to separate the pressure roller 13 from the heating roller 11 and release the pressure contact.

[0034]

According to the present invention, the power switch is turned on / off.
It is operated in conjunction with the OFF operation and the power switch is OF
Since the pressure contact releasing means for releasing the pressure contact between the pressure roller and the heating roller when the pressure is applied is provided, the fixing property can be stabilized and the durability of the pressure roller can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a state where pressure contact between a pressure roller and a heating roller according to an embodiment is released by using a pressure contact release means.

FIG. 3 is a perspective view for explaining the overall configuration of one embodiment.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an overall configuration of an image forming apparatus to which the fixing device of the embodiment is applied.

FIG. 6 is a sectional view showing a schematic configuration of a conventional image forming apparatus.

[Explanation of symbols]

 11 Heating Roller 12 Halogen Lamp (Heating Member) 13 Pressure Roller 20 Pressure Contact Release Means

Claims (1)

[Claims] 1. A fixing device for an image forming apparatus, comprising: a heating roller which has a heating member built therein and is driven to rotate in a sheet feeding direction; and a pressure roller which is rotated while being in pressure contact with the heating roller. A fixing device for an image forming apparatus, comprising a pressure contact releasing means for releasing pressure contact between the pressure roller and the heating roller when the power switch is turned off by being operated in conjunction with an ON / OFF operation.