JPH103224A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform fixing without rising fixing temperature though the diameter of a heating roller is small. SOLUTION: Plural sprockets 20 are provided at the outer peripheral surface of the heating roller 11 of a fixing device 1 with uniform intervals. A first roller 19 whose diameter is smaller than that of the heating roller 11 is provided on a downstream side in a paper carrying direction from the heating roller 11. A first belt 18 where plural holes 18a are formed on one end side with the uniform intervals is wound on the heating roller 11 and the first roller 19 by inserting the sprockets 20 into the holes 18a. A pressing roller 13 presses the heating roller 11 through the first belt 18.

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 fixing a toner image on a sheet by heating and pressing the sheet on which the toner image has been transferred.

[0002]

2. Description of the Related Art Conventionally, there is a fixing device having, for example, a heating roller and a pressure roller which is in pressure contact with the heating roller.
In such a fixing device, when the sheet on which the toner image is transferred is conveyed between the heating roller and the pressing roller, both rollers convey the sheet while heating and pressing, and the toner image is transferred onto the sheet. It was established.

[0003]

What determines the fixing performance of the fixing device is the amount of heat applied to the sheet and the nip amount between the heating roller and the pressure roller. In recent years, faster printing,
As printing apparatuses and the like having such a fixing device have been reduced in size, it has been necessary to perform a fixing operation in a short time. Therefore, in order to melt the toner in a short time, a method of increasing the fixing temperature applied to the heating roller, or increasing the pressing force of the pressing roller against the heating roller has been used.

However, in the conventional fixing device, if the fixing temperature applied to the heating roller is increased, it is necessary to increase the heat resistance of the printing device itself. Further, since the temperature inside the printing apparatus rises, the temperature inside the developing device containing the toner also rises, which may adversely affect the quality of the toner. For the nip amount,
Since the diameter of the heating roller becomes smaller with the miniaturization of the device,
The increase in the nip amount was structurally difficult.

[0005]

Means for Solving the Problems To solve the above problems, a solution taken by the present invention is to transfer a toner image-transferred sheet while heating and pressurizing the sheet by a heating roller and a pressure roller. In a fixing device for fixing an image to a sheet, a roller having a rotation center line parallel to the rotation center line of a heating roller, a belt wound around the roller and the heating roller, and the heat of the heating roller being transmitted, And a pressure roller that is in pressure contact with the heating roller via the belt and pinches and conveys the sheet together with the belt.

According to the above solution, when heat is applied to the heating roller, the heat is transmitted to the belt. When the paper on which the toner image has been transferred is conveyed between the belt and the pressure roller, the heat transmitted from the heating roller to the belt is transmitted to the paper, and the pressure roller presses the paper against the belt, whereby toner is removed. Melts. The paper is conveyed by the movement of the belt and the rotation of the pressure roller, and the paper receives heat from the belt until it passes through the belt.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a schematic perspective view showing the fixing device according to the embodiment, and FIG.
FIG. 3 is an enlarged cross-sectional view of the heating roller provided in the fixing device according to the first embodiment when an end is cut in a vertical direction with respect to a rotation center line.

The fixing device 1 includes a rotatable heating roller 11,
A first roller 19, a first belt 18, and a pressure roller 1 that presses the heating roller 11 via the first belt 18
3 is provided.

The heating roller 11 is made of aluminum and has a thin hollow shape. The heating roller 11 has a halogen lamp 12 for heating the heating roller 11 at a central portion thereof. A gear 17 is fixed to the outer peripheral surface of one end of the heating roller 11, and is rotated by transmitting a rotational force of a motor (not shown). A plurality of projections 20 (sprockets 20) are provided at equal intervals on the outer peripheral surface of the other end of the heating roller 11, as shown in FIG.

The surface temperature of the heating roller 11 is controlled to a predetermined temperature by a thermistor (not shown) or the like.

The first roller 19 is rotatably supported by the apparatus frame 1a at a position downstream of the heating roller 11 in the sheet conveying direction (direction of arrow A). First roller 1
The rotation center line 9 (not shown) is parallel to the rotation center line (not shown) of the heating roller 11. First roller 1
The diameter of 9 is set smaller than the diameter of the heating roller 11, and the heat capacity of the heating roller 11 is smaller than that of the heating roller 11.

The first belt 18 is connected to the heating roller 11 and the first belt 18.
Around the roller 19. First belt 1
Numeral 8 is made of metal, rubber, or the like, and its outer peripheral surface is coated with a fluororesin to prevent the toner fixed on the paper 15 from sticking to the first belt 18 and becoming unremovable. The first belt 18 has a thickness of about 50 [μm]. On one edge side of the first belt 18, a plurality of holes 18a (see FIG. 1) are formed at equal intervals.

The size of the holes 18a is larger than that of the sprocket 20 described above, and the interval between the holes 18a is the same as the interval at which the sprockets 20 are formed. When the first belt 18 is wound around the heating roller 11 and the first roller 19, the sprocket 20 is inserted into the hole 18a and attached (see FIG. 2).

The tip of the sprocket 20 has a height that does not protrude from the outer peripheral surface of the first belt 18, and has a height that allows the rotational force of the heating roller 11 to be transmitted to the first belt 18. In addition, if the hole 18a is at a height where the sprocket 20 does not protrude from the outer peripheral surface of the first belt 18,
It may be a concave shape without penetrating. In this case, as long as the heat of the heating roller 11 can be uniformly transmitted to the first belt 18, the position where the hole is formed is not limited to the end.

The pressure roller 13 is formed of an elastic member such as rubber, and is provided to face the heating roller 11. The rotation center of the pressure roller 13 is located on a vertical line passing through the rotation center of the heating roller 11, and is rotatably supported by the apparatus frame 1a. Springs 14 are attached to both ends of the pressure roller 13, and the spring 14 causes the pressure roller 13 to move via the first belt 18 to the heating roller 11.
Press.

Next, the fixing operation of the first embodiment will be described with reference to FIGS.

First, when a power source of a device (not shown) incorporating the fixing device 1 (which is referred to as a printing device in the present embodiment) is turned on, the halogen lamp 12 is turned on, thereby heating the heating roller 11. The temperature of the heating roller 11 is controlled by a thermistor, and the first belt 18 is heated by the halogen lamp 12 through the heating roller 11 to reach a controlled set temperature. When the heating roller 11 and the contact portion of the first belt 18 with the heating roller 11 reach the set temperature, the motor starts rotating. The rotational force of the motor is transmitted to the gear 17, and the gear 17 is moved counterclockwise (in the direction of arrow B).
To rotate.

The rotation of the gear 17 causes the heating roller 11 to rotate in the same direction.
By 0, the first belt 18 moves in the arrow C direction. At this time, the first roller 19 rotates in the direction of arrow B due to friction between the surface of the first roller 19 and the first belt 18.

Further, as the first belt 18 moves, the pressure roller 13 pressed against the first belt 18 by the spring 14 rotates in the direction of arrow D due to friction with the first belt 18. .

In the above state, the temperature is controlled by the thermistor, the halogen lamp 12 repeats blinking, the rollers 11, 13, and 19 rotate, and the first belt 18 moves while maintaining the set temperature.

When print data is transmitted by a personal computer (not shown) connected to the printing apparatus, a printing operation is started,
The sheet 15 to which the unfixed toner image 16 has been transferred is transported to the fixing device 1 by a transport unit (not shown). Paper is first
When it is sent between the belt 18 and the pressure roller 13, it receives heat from the first belt 18 which is controlled to the set temperature. At the same time, a pressing force is applied by the pressure roller 13, and the toner image melts and permeates and fixes on the sheet 15.

The sheet 15 is adhered to the first belt 18 by the fixed toner, or the first belt 18
Belt 18 and pressure roller 13
Transported by At this time, even if all of the toner image 16 remains without being completely melted, the paper 15 passes through the space between the heating roller 11 and the pressure roller 13 and then the toner of the paper 15 is heated by the heat of the first belt 17. Heat is continuously applied to the image 16, and the toner in an incompletely fixed state is melted to be in a completely fixed state.

Thereafter, the paper 15 is discharged from a device discharge port (not shown). When the paper 15 is transported in a state of being stuck to the first belt 18, if the head of the paper 15 is transported away from the direction of arrow A by the curvature of the first roller 19, the paper 15 is elastically deformed. It peels off from the first belt 18 and is sent in the direction of arrow A.

In the first embodiment, the first roller 19 is arranged along the direction of arrow A. However, the present invention is not limited to this, and the paper 1 passing between the heating roller 11 and the pressure roller 13 is not limited to this.
The first belt 18 may be inclined with respect to the direction of arrow A as long as the toner in the incompletely fixed state can be melted by applying heat to the first belt 18 from the first belt 18.

In the first embodiment, heat is applied to the first belt 18 wound around the heating roller 11 and the first roller 19 to maintain the temperature at the set temperature. Heat can be continuously applied to the paper 15 that has passed through the gap. Therefore, when there is a toner that is in an incompletely fixed state on the sheet 15 that has passed between the heating roller 11 and the pressure roller 13, the toner can be melted to ensure a complete fixing state.

Further, by providing the first belt 18, even if the diameter of the heating roller 11 is reduced, the nip amount is not reduced accordingly, and the pressure roller 13 The nip amount can be increased as compared with the case where the pressure is directly pressed.

In the first embodiment, the rotational force of the heating roller 11 is transmitted to the first belt 18 by inserting the sprocket 20 of the heating roller 11 into the hole 18a of the first belt 18. The rotational force of the heating roller 11 may be transmitted to the first belt 18 using the friction between the heating roller 11 and the first belt 18.

By the way, the first roller 19 is disposed upstream of the heating roller 11 in the transport direction, and the first belt 18 is
Before the paper 15 is conveyed between the pressure roller 13 and
Heat may be applied to the paper 15 from the first belt 18 first.

Second Embodiment In a second embodiment, a heating roller 11 and a pressure roller 13
And a second belt that nips and conveys the sheet that has passed between the first belt 18 and the first belt 18. Hereinafter, a second embodiment will be described with reference to FIG. FIG. 3 is an enlarged sectional view of an end portion of the fixing device according to the second embodiment.

The fixing device 50 has a second roller 5 having the same size as the pressure roller 13 at a position facing the first roller 19.
1 is provided. The second roller 51 is arranged in parallel with the pressure roller 13 so that the rotation center is located on the same horizontal line as the rotation center of the pressure roller 13. Then, the second belt 52 is attached to the pressure roller 13 and the second roller 51.
Is wound around.

The second belt 52 is formed of the same material as the pressure roller 13. Since the second belt 52 is in contact with the first belt 18 and the pressing roller 13 presses the heating roller 11 via the first and second belts 18 and 52 by the spring 14, the first belt Move in the direction of arrow E due to friction as the belt 18 moves.

The second belt 52 is driven by the first belt 52 by friction.
It may be formed of a metal or the like as long as it can be moved together with the belt 18.

The other structure is the same as that of the first embodiment.

Next, the fixing operation of the second embodiment will be described with reference to FIG. The operation from turning on the power until the contact portion of the heating roller 11 and the first belt 18 with the heating roller 11 reaches the set temperature is the same as that of the first embodiment, and the description is omitted. .

When the motor starts rotating and the gear 17 and the heating roller 11 rotate in the direction of arrow B, the first belt 1
8 is moved by the sprocket 20 in the direction of arrow C. At this time, the first roller 19 rotates in the direction of arrow B due to friction between the surface of the first roller 19 and the first belt 18.

Further, as the first belt 18 moves, the second belt 52 moves in the direction of arrow E while rotating the pressure roller 13 and the second roller 51 in the direction of arrow D, respectively.

In the above state, the temperature is controlled by the thermistor, the halogen lamp 12 repeats blinking, the rollers 11, 13, and 19 rotate, and the first belt 18 moves while maintaining the set temperature.

When print data is sent out by a personal computer or the like, a printing operation is started, and the paper 15 on which the toner image 16 has been transferred is transported to the fixing device 1 by a transport means (not shown). When the sheet 15 is sent between the first and second belts 18 and 52, the sheet 15 receives heat from the first belt 18 which is controlled to the set temperature. At the same time, a pressing force is applied by the pressure roller 13 via the second belt 52, and the unfixed toner image is melted, permeates the paper 15 and is fixed.

The sheet 15 is nipped and conveyed by the first and second belts 18 and 52. At this time, even if all of the toner image 16 remains without being completely melted, the first belt 1
Heat is applied to the toner image 16 on the sheet 15 by the heat of the sheet 8, and the toner in an incompletely fixed state is melted to be in a completely fixed state.

When the leading edge of the sheet 15 is conveyed in a direction away from the direction of arrow A by the curvature of the first roller 19, the sheet 15 is moved by the elasticity of the first belt, as in the first embodiment. Peel from 18. Thereafter, the paper is discharged from the apparatus discharge port. In the second embodiment, by providing the second belt 52 in contact with the first belt 18, the paper 15 is moved until the paper 15 passes between the first and second rollers 19 and 51. It can be transported in contact with the first belt 18. Therefore, the heat of the first belt 18 can be reliably transmitted to the sheet 15, and the fixing property can be improved as compared with the first embodiment.

Third Embodiment In the second embodiment, the second belt 52 is moved by friction with the first belt 18, but in the third embodiment, the heating roller 11 It is moved using the formed sprocket. Hereinafter, the third embodiment will be described with reference to FIGS. FIG. 4 is a schematic perspective view showing a fixing device according to the third embodiment, and FIG. 5 is an enlarged sectional view of an end portion of the fixing device according to the third embodiment.

Second belt 10 provided in fixing device 100
1 has the same size as the hole 18a of the first belt 18,
A plurality of holes 101a are formed at the same intervals as the intervals at which the holes 18a are formed. The heating roller 11 has a sprocket 102 having a height higher than the sprocket 20 described above.
However, it is formed instead of the sprocket 20. More specifically, as shown in FIG.
a, 101a. Note that sprocket 1
02 is in non-contact with the pressure roller 13.

Other structures are the same as in the second embodiment.

Next, the fixing operation of the third embodiment will be described with reference to FIGS. The operation from turning on the power until the contact portion of the heating roller 11 and the first belt 18 with the heating roller 11 reaches the set temperature is the same as that of the first embodiment, and the description is omitted. .

When the motor starts rotating and the gear 17 and the heating roller 11 rotate in the direction of arrow B, the first belt 1
8 is moved by the sprocket 102 in the direction of arrow C.
At this time, the first roller 19 rotates in the direction of arrow B due to friction between the surface of the first roller 19 and the first belt 18.

At the same time, the sprocket 102 is
The second belt 52 enters the pressure roller 13 and the second belt 52.
While rotating the rollers 51 in the direction of arrow D, respectively.
Move in the direction.

After that, the operation from the start of the printing operation to the discharge of the sheet 15 is the same as that of the second embodiment, and the description is omitted.

In the third embodiment, the sprocket 102
, The first and second belts 18 and 52 are moved, so that the paper 15 sandwiched between the first and second belts 18 and 52 is displaced from the first and second belts 18 and 52. It does not cause it to occur. Therefore, it is possible to prevent deterioration of print quality due to defective fixing caused by misalignment as compared with the second embodiment, and to prevent paper jam.

In the second and third embodiments, the second roller 51 is formed to have the same size as the pressure roller 13, but need not be the same size as the pressure roller 13.

First Roller 1 of First to Third Embodiments
Since the curvature becomes smaller as the diameter of the sheet 9 becomes smaller, the sheet 15 is easily peeled off from the first belt 18 when the sheet 15 is conveyed in a state of being stuck to the first belt 18. Therefore, it is not necessary to provide a separation claw or the like for separating the sheet 15 from the first belt 18.

In the first to third embodiments, the first and second
Although the rollers 19 and 51 and the pressure roller 13 are rotated by friction, they may be rotated by using a drive source separately.

In the first to third embodiments, the heating roller 11 and the first belt 1 are formed by using a halogen lamp.
Although the heat is applied to 8, for example, a heater or the like may be used. Alternatively, a current may be supplied to the heating roller to generate heat.

[0053]

As described in detail above, the present invention provides
The belt is wound around the roller and the heating roller, the heat given to the heating roller is transmitted to the belt, and the belt is heated until the paper conveyed between the belt and the pressure roller is separated from the belt. It is not necessary to raise the fixing temperature even if the diameter of the roller is small. As a result, there is no need to increase the heat resistance of the printing apparatus itself, and further, since the temperature inside the printing apparatus does not increase, there is no possibility that the quality of the toner is adversely affected. Further, even if the diameter of the heating roller is small, the nip amount is not reduced because the belt and the pressure roller are in direct contact.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a first fixing device according to the present invention.

FIG. 2 is an enlarged sectional view of an end portion of the fixing device according to the first embodiment.

FIG. 3 is an enlarged sectional view of an end portion of a fixing device according to a second embodiment.

FIG. 4 is a schematic perspective view illustrating a fixing device according to a third embodiment.

FIG. 5 is an enlarged sectional view of an end portion of a fixing device according to a third embodiment.

[Explanation of symbols]

 1, 50, 100 Fixing device 11 Heating roller 13 Pressure roller 15 Paper 18 First belt 19 First roller 51 Second roller 52, 101 Second belt

Claims (5)

[Claims] 1. A fixing device for fixing a toner image on a sheet by transporting the sheet on which the toner image has been transferred while heating and pressing the sheet with a heating roller and a pressing roller, wherein the fixing roller rotates parallel to a rotation center line of the heating roller. A roller on which a center line is located; a belt wound around the roller and the heating roller, to which heat of the heating roller is transmitted; and a pressure roller which is in pressure contact with the heating roller via the belt to pinch and convey the sheet together with the belt. A fixing device comprising a pressure roller. 2. The fixing device according to claim 1, wherein the roller is disposed downstream of the heating roller in a sheet conveying direction. 3. The fixing device according to claim 1, wherein a protrusion is provided on the heating roller, and a hole in which the protrusion is inserted when the belt is wound around the heating roller is formed in the belt. . 4. A second roller, wherein the roller is a first roller and is disposed downstream of the pressure roller in the sheet conveying direction, and has a rotation center line parallel to a rotation center line of the pressure roller. A first belt, and a second belt for nipping and conveying the sheet together with the first belt is connected to the pressure roller and the second belt.
4. The fixing device according to claim 3, wherein the fixing device is wound around the roller. 5. The fixing device according to claim 4, wherein the height of the protrusion is higher than the thickness of the first belt, and a hole into which the tip of the protrusion is inserted is formed in the second belt.