JPH10123877A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a roller, etc., due to pressure by attaining the pressurized and pressure-released states of a fixing device with a simple constitution. SOLUTION: This image forming device having the fixing unit (fixing device) 10 is provided with fixing/infixing mean (a locking member 3a, a cam 3b and a lever 3c) for fixing/releasing the fixing unit 10 to/from a device main body at the time of attaching/detecting the fixing unit 10 to/from the device main body, to obtain the pressurized state where the pressure required from fixing an unfixed image is produced at the time of fixing the fixing unit 10 and the pressurization-released state where this pressurization is released at the time of releasing the fixing unit 10 in synchronization with the operation of the fixing/unfixing means. Thus, the fixing unit 10 becomes the pressurized state or the pressure-released state, in synchronization with the operation of the fixing/unfixing means when the fixing unit 10 is attached to/detached from the device main body, so that the pressurized and pressure-released states of the fixing unit are attained to prevent the deformation of the roller, etc., caused by the pressure, with a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art In an image forming apparatus such as a printer or a copying machine, a drive of a pressure release mechanism by a cam or the like is electrically controlled by a solenoid to prevent deformation of a roller or the like due to pressure.
It is common to provide a mechanism in the device body to automatically release pressure by connecting / disconnecting with a clutch, etc. Was done.

[0003]

However, the conventional mechanism for releasing the automatic pressure, for example, requires complicated mechanisms such as a clutch, a solenoid, and a cam mechanism in addition to the electric control. However, there have been problems such as a decrease in reliability due to an increase in failure factors.

In addition, when the manual pressure is released by attaching or detaching the spacer or the like, problems such as a defective fixing due to forgetting to remove the spacer and a deformation of the roller due to forgetting to attach the spacer have occurred.

Accordingly, an object of the present invention is to provide an image forming apparatus capable of realizing a pressurized state and a depressurized state of a fixing device with a simple configuration and preventing deformation of rollers and the like due to pressure. It is in.

Further, when thick paper such as an envelope is fixed at a pressure similar to that of plain paper, the pressure substantially increases and troubles such as wrinkles occur.

Accordingly, an object of the present invention is to provide an image forming apparatus capable of preventing occurrence of troubles such as wrinkling of thick paper.

[0008]

According to a first aspect of the present invention, there is provided an image forming apparatus including a fixing device for fixing an unfixed image on a sheet by using at least pressure. A fixing / releasing means for fixing / unfixing the fixing device to / from the apparatus main body when attaching / detaching to / from the apparatus main body, which is necessary for fixing the unfixed image in synchronization with the operation of the fixing / releasing means. The pressure to be applied is set to a pressurized state generated when the fixing device is fixed, and the pressure is released to release the same pressure when the fixing device is fixed.

According to a second aspect of the present invention, in the first aspect of the present invention, a reduced pressure state is provided between the pressurized state and the released pressure state. Thus, an appropriate pressure for thick paper can be set.

Therefore, according to the first aspect of the present invention, the fixing device can be brought into the pressurized state or the pressure released state in synchronization with the operation of the fixing / releasing means when the fixing device is attached to / detached from the apparatus main body. With the simple configuration, the pressed state and the released state of the fixing device can be realized to prevent the deformation of the roller and the like due to the pressure.

According to the second aspect of the present invention, a depressurized state is provided between the pressurized state and the depressurized state. Since the appropriate pressure can be set, occurrence of troubles such as wrinkling of thick paper can be prevented.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a main sectional view of a fixing unit of an image forming apparatus according to a first embodiment of the present invention in a pressurized state, and FIG. FIG. 3 is a side view of the identification landing unit in a pressure released state, and FIG.
Is a side view of the image forming apparatus main body when the fixing unit is mounted, and FIG. 5 is a side view of the image forming apparatus main body when the fixing unit is depressurized.

An image forming apparatus main body 11 shown in FIGS.
Inside, a fixing unit 10 for fixing an unfixed image transferred onto a sheet of paper (not shown) to the sheet by heat and pressure.
(See FIGS. 1 to 3). The fixing unit 10 is used to apply pressure to the fixing roller 1 and the pressure roller 2 that directly contact paper and apply heat and pressure. A pressure arm 4 swingably mounted on a fulcrum 5, a spring 7 for generating a pressing force on the pressure roller 2, a heater 6 for applying heat to the fixing roller 1, and a drive (not shown) in the apparatus main body 11. A drive gear 8 for transmitting a driving force from a source, a lock member 3 a for fixing the fixing unit 10 to the apparatus main body 11 (see FIGS. 3 to 5), and a lock member 3.
and a cam 3b (see FIGS. 3 to 5) which is integrated with the a and presses down the pressing arm 4 by a rotational force.

When the apparatus main body 11 is used normally, in the fixing unit 10 mounted on the apparatus main body 11, the fixing roller 1 and the pressure roller 2 heated by the heater 6 are connected to the apparatus main body 11 side. It rotates by receiving a driving force from a driving source (not shown) via a driving gear 8. At this time, the pressure generated by the spring 7 is applied to the receiving portion 4a of the pressing arm 4 swinging about the fulcrum 5 and transmitted as a pressing force for pressing the pressing roller 2 against the fixing roller 1. The sheet carrying the unfixed image passes between the fixing roller 1 and the pressure roller 2 which are rotated by the application of the pressure and heat, so that the unfixed image is fixed on the sheet.

The lock member 3a is rotatable about a shaft 9. When the lever 3c is pushed down as shown in FIG. 4, the lock member 3a engages with the notch 12 provided in the apparatus body 11, The fixing unit 10 is an apparatus main body 11
Fixed to

When the apparatus main body 11 is not used for a long period of time or when the fixing unit 10 is taken out of the apparatus main body 11 for some reason, the lever 3c is moved right and left around the shaft 9 shown in FIGS. Push up each. Then, the lock member 3a is released from the notch 12, and the fixing unit 10 can be pulled out from the apparatus main body 11 to the near side in FIGS. At this time, the cam 3b integrated with the lock member 3a rotates about the shaft 9 by operating the lever 3c, abuts against the receiving portion 4a of the pressing arm 4 to compress the spring 7, and the pressing arm 4 Press down to fix it. As a result, as shown in FIG. 2, the pressing roller 2 is also pushed down, and the pressing roller 2 is separated from the fixing roller 1, so that the deformation of the fixing roller 1 and the pressing roller 2 due to the pressure is prevented. .

When the use of the apparatus main body 11 is started or when the used fixing unit is replaced with a new fixing unit, the contact of the cam 3b with the pressing arm 4 is released by pushing down the lever 3c. Then, the pressure arm 4 is pushed up by the pressure of the spring 7, and the pressure roller 2 comes into contact with the fixing roller 1, and the fixing state shown in FIG. 1 is obtained.

When a used fixing unit is replaced with a new fixing unit, a new replacement fixing unit (service part) is shipped from the factory with the fixing roller and the pressure roller separated from each other. This prevents the roller from being deformed at the time of stock.

Thus, according to the present embodiment, the lever 3
By simply operating c, detachment of the fixing unit 10 from the apparatus main body 11 and separation and contact of the fixing roller 1 and the pressure roller 2 can be simultaneously performed.

As shown in FIG. 5, in this embodiment, the pressure is reduced to a pressure suitable for fixing thick paper such as an envelope between the pressure release state shown in FIG. 3 and the pressurized state shown in FIG. The cardboard position is set. When the lever 3c is rotated about the shaft 9 and the cam 3b pushes down the receiving portion 4a of the pressurizing arm 4, the pressurizing arm 4 reaches a proper pressure in advance between the time when the cam 3b is pressurized and the time when the pressure is released. 3b to push down
Is set. In this state, the lock member 3a is not released from the notch 12, the pressure of the fixing unit 10 is reduced while being fixed to the main body 11, and the operation of rotating the lever 3c to this position when fixing thick paper such as an envelope is performed. Appropriate pressure for cardboard is ensured.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a main cross-sectional view of the fixing unit of the image forming apparatus according to Embodiment 2 of the present invention in a pressure released state, and FIG. 7 is a main cross-sectional view of the identification mounting unit when the apparatus main body is mounted. In these drawings, the same elements as those shown in FIGS. 1 to 5 are denoted by the same reference numerals, and description thereof will be omitted below.

6 and 7, reference numeral 13 denotes a pressure releasing arm for releasing the pressure of the spring 7, 16 a lock member for fixing the fixing unit 10 to the apparatus main body 11, and 14 a fixing member for fixing the fixing unit 10 to the apparatus main body 11. A fixed fulcrum 15 serving as a fulcrum in this case is a fulcrum receiver on the apparatus body 11 side.

As in the first embodiment, the pressure arm 4 is rotatable around the fulcrum 5, and the pressure generated by the spring 7 is applied to the pressure roller 2 by the pressure arm 4. The lower portion of the spring 7 is held by a pressure release arm 13 that can swing about the fulcrum 5. For this reason, as shown in FIG. 6, when the fixing unit 10 is floated inside, the pressure of the spring 7 is not generated, and the pressure roller 2 is separated from the fixing roller 1.

Similarly, when the fixing unit 10 is placed as a single unit, only the own weight of the fixing unit 10 acts. For this reason, when the fixing unit 10 is mounted on the apparatus main body 11, as shown in FIG.
At the same time as fixing the fixing unit 10 by bringing the
A force is applied to push the fixing unit 10 downward about the fixed fulcrum 14. At this time, the release arm 13 is already in contact with the bottom portion 17 of the apparatus main body 11, and the release arm 13 presses the spring 7 by this force. As a result, an appropriate pressure is secured between the pressure roller 2 and the fixing roller 1. To fix it.

[0026]

As is apparent from the above description, claim 1
According to the invention described above, the fixing device can be brought into the pressurized state or the pressure released state in synchronization with the operation of the fixing / releasing means when the fixing device is attached to or detached from the apparatus main body. An effect is obtained in that a pressurized state and a pressure released state can be realized to prevent deformation of a roller or the like due to pressure.

According to the second aspect of the present invention, a reduced pressure state is provided between the pressurized state and the released pressure state. Since the appropriate pressure can be set, it is possible to prevent the occurrence of troubles such as wrinkles of thick paper.

[Brief description of the drawings]

FIG. 1 is a main cross-sectional view of a fixing unit of an image forming apparatus according to Embodiment 1 of the present invention in a pressed state.

FIG. 2 is a main cross-sectional view of the fixing unit of the image forming apparatus according to Embodiment 1 of the present invention in a pressure released state.

FIG. 3 is a side view of the fixing unit of the image forming apparatus according to Embodiment 1 of the present invention in a pressure released state.

FIG. 4 is a side view of the image forming apparatus main body when a fixing unit is mounted.

FIG. 5 is a side view of the image forming apparatus main body when the pressure of the fixing unit is reduced.

FIG. 6 is a main cross-sectional view of the fixing unit of the image forming apparatus according to Embodiment 2 of the present invention in a pressure released state.

FIG. 7 is a main cross-sectional view illustrating a state where the fixing unit of the image forming apparatus according to Embodiment 2 of the present invention is mounted on the apparatus main body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3a Lock member (fixing / releasing means) 3b Cam (fixing / releasing means) 3c Lever (fixing / releasing means) 4 Pressure arm 7 Spring 10 Fixing unit 11 Device body

Claims (2)

[Claims] 1. An image forming apparatus comprising a fixing device for fixing an unfixed image to a sheet using at least pressure, wherein the fixing device is fixed to and fixed to the apparatus main body when the fixing apparatus is attached to and detached from the apparatus main body. A fixing / releasing unit for releasing is provided, and a pressure required to fix the unfixed image in synchronization with the operation of the fixing / releasing unit is set to a pressurized state generated when the fixing device is fixed, and An image forming apparatus, wherein the pressure is released when the fixing is released. 2. A depressurized state is provided between the pressurized state and the pressure released state. In the depressurized state, an appropriate pressure for thick paper can be set by reducing the pressure at the time of pressurization. The image forming apparatus according to claim 1, wherein: