JPH06324599A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device which is so excellent in dismantling property that it can enhance environmental protection and serviceability. CONSTITUTION:In a fixing device 1 comprising a fixing frame 2, a fixing roller 3 freely rotatably held on the fixing frame 2, a temperature sensor 6 for detecting the surface temperature of the fixing roller 3, and a removable presser bar spring 9 for pressing the temperature sensor 6 into contact with the fixing roller 3, a fixing means for the presser bar spring 9 comprises a first rotation regulating means for regulating rotation of the temperature sensor 6 in the direction (R1) of rotation of the fixing roller 3 and a second rotation regulating means for regulating rotation of the sensor 6 in the opposite direction. Then the temperature sensor 6 can be mounted and held in place without use of screws, so the dismantling property of the fixing device 1, and thus environmental protection and serviceability, can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a laser beam printer and an LED printer.
The present invention relates to a fixing device for fixing a toner image formed on a sheet by an electrophotographic process to the sheet by heat.

[0002]

2. Description of the Related Art As a fixing device for an image forming apparatus such as a laser beam printer which records an image by an electrophotographic process, a fixing device for fixing the toner image on the paper by heating the paper carrying the toner image is known. Is generally known.

FIG. 9 shows a schematic structure of such a fixing device.
The fixing device 1 shown in FIG. 9 has a hollow cylindrical fixing roller 3, which is rotatably held near the end by a bearing (not shown) mounted on the fixing frame 2 and rotates at a predetermined rotation speed.
The center of the fixing roller 3 includes a rod-shaped heater 4 fixedly arranged in parallel with the longitudinal direction of the fixing roller 3, a pressure roller 5 made of rubber arranged so as to face the fixing roller 3, and the like. Then, the pressure roller 5 abuts on the fixing roller 3 with a predetermined pressure by a pressure spring (not shown) and is driven to rotate. .

A temperature sensor 6 is provided on the fixing roller 3.
The temperature switch 7 and the temperature switch 7 are arranged in pressure contact by a spring (not shown). The temperature sensor 6 detects the surface temperature of the fixing roller 3 heated by the heater 4, and a temperature control unit (not shown) controls the heater 4 based on the detected surface temperature to control the temperature of the fixing roller 3. The temperature switch 7
Is for detecting the abnormal heating of the surface of the fixing roller 3 above the temperature for normal use and stopping the heating.

By the way, the temperature sensor 6 and the temperature switch 7 are located outside the sheet passing area, that is, near the end portion of the fixing roller 3,
Alternatively, it is disposed near the central portion of the sheet passing area together with the cleaning member that is in contact with the fixing roller 3.

The sheet P on which a toner image has been formed by a predetermined electrophotographic process is guided and caught by the fixing roller 3 and the pressure roller 5, and the toner image is fixed by heat and pressure. .

[0007]

By the way, in the fixing device 1, as shown in FIG.
Is fixed to the substrate 8, the substrate 8 is fixed to or supported by the pressing spring 9, and the pressing spring 9 is fixed to the fixing frame 2 with the screw 10.

On the other hand, in recent years, from the standpoint of environmental protection, reuse of various industrial products, that is, so-called recycling has been demanded, and the demand has been increasing year by year. Image forming apparatuses such as laser beam printers are no exception, and improvement of disassembly of the apparatus main body is one improvement item.

However, in the conventional fixing device 1 shown in FIG. 10, the screw 1 is used to remove the temperature sensor 6 with a screwdriver.
You have to remove 0 each time.

By the way, making it easier to remove the parts of the fixing device that become extremely hot is
Although strongly demanded from the viewpoint of serviceability and safety in the market, the conventional fixing device 1 cannot meet the demand.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fixing device which is excellent in dismantling property and is capable of environmental protection and serviceability improvement.

[0012]

To achieve the above object, the present invention provides a fixing frame, a fixing roller rotatably held by the fixing frame, and a temperature sensor for detecting the surface temperature of the fixing roller. In a fixing device including a detachable pressing spring that presses the temperature sensor against the fixing roller, a fixing means for fixing the pressing spring restricts rotation of the temperature sensor in a rotation direction of the fixing roller. It is characterized in that it is constituted by a first rotation restriction means and a second rotation restriction means for restricting rotation of the fixing roller of the same temperature sensor in a direction opposite to the rotation direction.

[0013]

According to the present invention, since the temperature sensor can be attached and held without using screws, disassembly of the fixing device can be enhanced, and environmental protection and serviceability can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. <First Embodiment> FIGS. 1 to 3 are views showing a first embodiment of the present invention. FIG. 1 is a sectional view of a fixing device, FIG. 2 is an exploded perspective view of an essential part of an identification fixing device, and FIG. FIG. 3 is a cross-sectional view showing a state in which the fixing device is attached to the image forming apparatus main body.

In the fixing device 1 shown in FIG. 1, 2 is a fixing frame, 3 is a fixing roller, 4 is a heater, and 5 is a pressure roller. The fixing roller 3 and the pressure roller 5 rotate in the directions indicated by arrows R1 and R2, respectively.

Reference numeral 6 denotes a temperature sensor for detecting the surface temperature of the fixing roller 3, which is fixed to a substrate 8 fixed to or held by a holding spring 9. Presser spring 9
Is formed in a substantially U shape, which is slightly open as shown by a two-dot chain line in FIG. 1 in a free state before mounting.
At the time of mounting, the pressing spring 9 is partially inserted into the hole 2-a of the fixing frame 2 from the direction of the arrow X, and is pushed until the frame abutting portion 9-a abuts the wall 2-b of the fixing frame 2. Be done.

When the pressing spring 9 is attached as described above,
The stopper member 11 is mounted from above. The stopper member 11 is formed in a rectangular flat plate shape as shown in FIG. 2, and a round hole 11a and a round elongated hole 11b are provided near both ends thereof.
Are formed. On the other hand, the fixing frame 2 is provided with two columnar projections 2-c on both sides of the hole 2-a into which the pressing spring 9 is to be inserted, and the columnar projections 2-c are provided on the stopper member 11. The formed round hole 11a and round elongated hole 1
It matches 1b.

Thus, when the fixing device 1 is mounted on the image forming apparatus main body, the round hole 11a and the round elongated hole 1 of the stopper member 11 are provided.
The stopper member 11 is applied to the fixing frame 2 while aligning 1b with the cylindrical projection 2-c of the fixing frame 2. And
As shown in FIG. 3, when the fixing device 1 is mounted on the main body of the image forming apparatus, a gap is formed between the abutting portion 13 and the stopper member 11 which are integrally formed on the frame 12 of the image forming apparatus.
A slight gap is formed in consideration of the error of each component.

In the above-mentioned structure, the presser spring 9 is composed of the sensor pressure portion 9-b and the opposite side 9-c, and the temperature sensor 6 is provided.
An appropriate pressure is applied between the fixing roller 3 and the fixing roller 3. At this time, since the fixing roller 3 rotates in the direction of arrow R1, the temperature sensor 6 is pulled leftward in FIG. However, since the pressing spring 9 abuts on the fixing frame 2, the temperature sensor 6 is held stationary.

Even when an impact load is applied in the direction of arrow S, the pressing spring 9 abuts on the stopper member 11, so that the pressing spring 9 moves by the gap between the stopper member 11 and the main body abutting portion 13, but thereafter. The rotation of the fixing roller 3 causes the temperature sensor 6 to be pulled leftward in FIG. 1 and returns to the original position again.

As described above, according to this embodiment, the temperature sensor 6 and the presser spring 9 can be securely held and fixed without using screws, and even if the presser spring 9 is slightly moved, By rotating the fixing roller 3 again, the temperature sensor 6 can be always brought into contact with a predetermined position of the fixing roller 3 with a predetermined pressure, and as a result, disassembling property and serviceability of the fixing device 1 are improved. You can <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. 4. FIG. 4 is a sectional view showing a state in which the fixing device according to the second embodiment is attached to the image forming apparatus main body.

In the first embodiment described above, the stopper spring 11 is used to prevent the pressing spring 9 from coming off when an impact load is applied, but in the present embodiment, as shown in FIG. The fixing device 1 itself is not provided with a retaining member, but is provided on the image forming apparatus main body side.

That is, when the fixing device 1 is mounted on the main body of the image forming apparatus, the fixing device 1 is fixed with the abutting portion 14 on the main body side being close to the pressing spring 9. Therefore, when the fixing device 1 is detached from the main body of the image forming apparatus, the retaining member for the presser spring 9 disappears, but due to the pressure pressing the temperature sensor 6 against the fixing roller 3, a light pulling force is required to attach and detach the temperature sensor 6. Therefore, even if the fixing device 1 is rotated clockwise by an angle of 90 °, the temperature sensor 6 and the pressing spring 9 do not fall by their own weight.

As a result, as in the first embodiment, the disassembly of the fixing device 1 is improved, the number of parts can be reduced, and the cost can be reduced. <Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS. 5 is a cross-sectional view of the fixing device according to the third embodiment, and FIG. 6 is a cross-sectional view showing a state in which the identification fixing device is attached to the image forming apparatus main body.

In the second embodiment, the stopper member is not provided on the fixing device 1 itself but is provided on the image forming apparatus main body side. However, in the present embodiment, as shown in FIG.
The holding spring 9 is prevented from coming off by using the conveyance guide member 15 that forms the conveyance path of the sheet P (see FIG. 6) after the fixing is completed.

The conveying guide member 15 is fixed to the fixing device 1 after the pressing spring 9 is attached to the fixing device 1, and the frame abutting portion 9-a of the pressing spring 9 is fixed to the wall 2-b of the fixing frame 2. Narrow down. Then, when the fixing device 1 is mounted on the main body of the image forming apparatus, the conveyance guide portion 16 on the main body side and the conveyance guide member 15 of the fixing device 1 form a paper conveyance path after fixing as shown in FIG.

Thus, in this embodiment, the fixing device 1
Even if a large impact is applied after removing the sheet from the main body of the image forming apparatus, the temperature sensor 6 and the pressing spring 9 do not drop off, and the fixing frame 2 can also be removed by removing the conveyance guide member 15 from the fixing apparatus 1. . <Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. 7 is a sectional view showing a state in which the fixing device according to the fourth embodiment is mounted on the image forming apparatus main body, and FIG. 8 is a perspective view of the paper discharge guide member and the pressing spring.

In this embodiment, the conveyance guide member 17 is used as a retaining member for the pressing spring 18 when an impact load is applied, as in the second embodiment, but as shown in FIG. The member 17 differs from the second embodiment in that the member 17 is a member that forms a conveyance path for the sheet P before fixing, and the shape of the pressing spring 18 is different.

The conveyance guide member 17 is a member that forms a conveyance path for the sheet P before fixing, and is a contact portion between the fixing roller 3 and the pressure roller 5 for the sheet P sent to the fixing device 1. I will guide you to. The transport guide member 17 has a shape as shown in FIG. 8A, and a flat surface portion 17-1 on which the pressing spring 18 is to be mounted and an angular projection portion that vertically projects from the surface near one end thereof. 17-2 is provided.

On the other hand, the presser spring 18 is formed into a shape as shown in FIG. 8B and has a substantially U-shape like the presser spring 9 used in the first to third embodiments. However, it is formed of a flat plate except for the holding portion 18-1 that holds the substrate 8. A square hole 18-2 into which the protrusion 17-2 of the conveyance guide member 17 can be inserted with a slight gap is formed in a part of the flat plate portion of the pressing spring 18.

The above-mentioned conveyance guide member 17 and the pressing spring 18
When the sheet is incorporated into the fixing device 1, as shown in FIG. 7, the pressing spring 18 is sandwiched between the wall 2-d of the fixing frame 2 and the flat portion 17-1 of the sheet conveying guide member 17, and the sheet conveying guide member 17 is held. The protruding portion 17-2 is fitted into the square hole 18-2 of the presser spring 18, and thereby the presser spring 18 is positioned. The conveyance guide member 17 is the fixing frame
The round holes 17-3 formed at the two positions are fixed with screws.

Thus, according to this embodiment, in addition to the effect of the second embodiment, the shape of the pressing spring 18 is simplified,
Further cost reduction can be achieved.

[0033]

As is apparent from the above description, according to the present invention, the fixing frame, the fixing roller rotatably held by the fixing frame, the temperature sensor for detecting the surface temperature of the fixing roller, In a fixing device including a detachable pressing spring that presses the temperature sensor against the fixing roller, a fixing means for fixing the pressing spring restricts rotation of the temperature sensor in a rotation direction of the fixing roller. Since the first rotation restricting means and the second rotation restricting means for restricting the rotation of the fixing roller of the same temperature sensor in the direction opposite to the rotating direction of the fixing roller are constituted, the disassemblability of the fixing device is enhanced and the environment is preserved. Thus, the effect that the serviceability can be improved can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fixing device according to a first exemplary embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part of the fixing device according to the first exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state in which the fixing device according to the first exemplary embodiment of the present invention is mounted on the image forming apparatus main body.

FIG. 4 is a cross-sectional view showing a state in which the fixing device according to the second exemplary embodiment of the present invention is attached to the image forming apparatus main body.

FIG. 5 is a sectional view of a fixing device according to a third exemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a state in which the fixing device according to the third exemplary embodiment of the present invention is attached to the image forming apparatus main body.

FIG. 7 is a cross-sectional view showing a state in which a fixing device according to a fourth exemplary embodiment of the present invention is attached to an image forming apparatus main body.

FIG. 8 is a perspective view of a discharge guide member and a pressing spring.

FIG. 9 is a cross-sectional view showing a schematic configuration of a conventional fixing device.

FIG. 10 is a partially enlarged cross-sectional view of a conventional fixing device.

[Explanation of symbols]

 1 Fixing Device 2 Fixing Frame 3 Fixing Roller 4 Heater 5 Pressurizing Roller 7 Temperature Switch 8 Substrate 9,18 Presser Spring 10 Screw 11 Stopper Member 12-14 Main Body Abutting Part 15,17 Transfer Guide Member 16 Main Body Transfer Guide Part

Claims (4)

[Claims] 1. A fixing frame, a fixing roller rotatably held by the fixing frame, a temperature sensor for detecting a surface temperature of the fixing roller, and a detachable pressing spring for pressing the temperature sensor to the fixing roller. And a fixing roller of the temperature sensor, wherein the fixing means of the pressing spring includes a first rotation restricting means for restricting rotation of the temperature sensor in a rotation direction of the fixing roller, and a fixing roller of the temperature sensor. And a second rotation restricting means for restricting rotation in a direction opposite to the rotation direction of the fixing device. 2. The first rotation restricting means comprises the pressing spring having a substantially U shape and a pressing spring abutting portion provided on the fixing frame. Fixing device. 3. The fixing device according to claim 1, wherein the second rotation restricting unit is formed integrally with a frame of the image forming apparatus main body. 4. The fixing device according to claim 1, wherein the second rotation restricting unit is a conveyance path forming member that forms a conveyance path for the sheet.