JP2000242126A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of shortening the warming-up time required just after power is started to be supplied. SOLUTION: This device is equipped with a driving mechanism which makes a fixing belt 36 endlessly run, and a controller which controls the driving mechanism so that the belt 36 may be driven to run at a 2nd running speed V2 in the case of fixing operation. The controller controls the driving mechanism so that the belt 36 may be driven to run at a 1st running speed V1 lower than the 2nd running speed V2 in the case of the first run of the belt 36 after the power is supplied. The controller controls only a 1st heating source 32 to generate heat at the warming-up time, that is, until the temperature of a fixing roller 28 rises to a fixable temperature from the time just after the power is supplied, and controls both the 1st and the 2nd heating sources 32 and 33 to generate the heat in the case of fixing operation after the temperature of the roller 28 reaches the fixable temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in a copier, a printer, a facsimile or the like, for melting and pressing unfixed toner on a sheet and fixing the unfixed toner on the sheet.

[0002]

2. Description of the Related Art In a recent fixing device for an electrophotographic apparatus, as shown in FIG. 12, fixing is performed between a fixing roller R1 and a heating / tension roller (hereinafter simply referred to as "heating roller") R3. A technique has been developed in which a belt fixing method in which a belt B is stretched and a pressure roller R2 that presses the belt B from below through the fixing belt B is combined with preheating of the recording medium D. Thereby, the temperature of the nip portion can be set low by preheating, and the fixing belt B having a small heat capacity can be set.
Is used, the temperature of the fixing belt B is rapidly cooled when passing through the nip portion, and the cohesive force of the toner separated from the fixing belt B at the exit of the nip portion is increased. And a clear fixed image without offset can be obtained even when oilless or only a small amount of oil is applied. This device is known as a fixing device that solves the problems of releasability and oil application that could not be solved by the heating roller method.

The configuration of this conventional fixing device will be briefly described below. The fixing device includes a fixing roller R1, a pressure roller R2 disposed immediately below the fixing roller R1, and a side of the fixing roller R1 (an upstream side along a recording medium conveyance direction).
And a heating roller R3 disposed in the fixing roller R1.
A fixing belt B is stretched between the heating roller R3 and the heating roller R3.

An oil application roller R4 is provided above the fixing belt B. Further, a guide plate G as a recording medium support is provided with a gap below the fixing belt B.
And a heating path P for the recording medium is formed between the lower portion of the fixing belt B and the guide plate G. The fixing belt B is
The heating roller R3 is pressed by the pressing lever U in a direction separating from the fixing roller R1 to obtain a desired tension, and is driven by the fixing roller R1 to rotate stably without slipping or loosening. Can be done.

On the other hand, inside the heating roller R3, a heating heater H is provided as a heating source. Also, the heating roller R
3, a thermistor S is provided for measuring the surface temperature. Since the thermistor S measures the temperature of the test portion in the contact state, it is not preferable to make the thermistor S contact the paper passing area of the fixing belt B. Therefore, the thermistor S is brought into contact with the non-paper passing area of the fixing belt B.

In the conventional fixing device having the above-described configuration, a controller (not shown) controls the heating roller R3 during the fixing operation based on the temperature measured from the thermistor S.
The heat radiation amount of the heater H is controlled so that the surface temperature of the heater H becomes a set temperature at which fixing is possible. During the fixing operation, the controller sets the traveling speed of the fixing belt B to a speed that matches the process speed in the transfer unit.

[0007]

Therefore, at the time of so-called warm-up immediately after the power is turned on, the fixing roller R
It has been pointed out that the temperature at the rolling contact portion between the roller 1 and the pressure roller R2 does not rise easily, and a long warm-up time is required. In particular, if it takes time until the first image forming operation is performed after the power is turned on, the operator is irritated, and the reduction in commercial value is directly impressed. I have.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a fixing device capable of shortening a warm-up time immediately after power-on.

[0009]

Means for Solving the Problems The above-mentioned problems are solved,
According to a first aspect of the present invention, there is provided a fixing device including a fixing roller, a pressing roller that is in contact with the fixing roller at a predetermined pressure, and a distance from the fixing roller. A heating roller having a first heat generating means disposed therein, and an endless loop between the heating roller and the fixing roller. The fixing roller receives heat from the first heat generating means. And a fixing belt for heating the unfixed toner on the sheet passing through the rolling contact portion of the pressure roller, and the sheet having the unfixed toner carried on the surface passes through the rolling contact portion in one direction. By doing
In a fixing device for fixing the unfixed toner on the sheet, a driving unit for driving the fixing belt endlessly runs, and the driving unit for driving the fixing belt to run at a second running speed during a fixing operation. Control means for controlling the fixing belt to drive the fixing belt at a first traveling speed lower than the second traveling speed when the fixing belt first travels after power is turned on. The driving means is controlled as described above.

According to a second aspect of the present invention, there is provided a fixing device, comprising: a fixing roller; a pressure roller which rolls on the fixing roller at a predetermined pressure; and a distance from the fixing roller. A heating roller in which a first heat generating means is disposed, and the heating roller and the fixing roller are endlessly wrapped around the heating roller, and the fixing roller and the fixing roller receive heat transfer from the first heat generating means. A fixing belt that heats the unfixed toner on the sheet passing through the rolling contact portion of the pressure roller, wherein the sheet having the unfixed toner carried on its surface passes through the rolling contact portion in one direction. By doing
In a fixing device for fixing the unfixed toner on the sheet, a driving unit for driving the fixing belt endlessly runs, and the driving unit for driving the fixing belt to run at a second running speed during a fixing operation. And control means for controlling the control means.
The driving unit is controlled such that the fixing belt is driven to travel at a first traveling speed lower than the second traveling speed.

According to a third aspect of the present invention, there is provided a fixing device, wherein a fixing roller, a pressing roller which rolls on the fixing roller at a predetermined pressure, and a distance from the fixing roller are provided. A heating roller in which a first heat generating means is disposed, and the heating roller and the fixing roller are endlessly wrapped around the heating roller, and the fixing roller and the fixing roller receive heat transfer from the first heat generating means. A fixing belt that heats the unfixed toner on the sheet passing through the rolling contact portion of the pressure roller, wherein the sheet having the unfixed toner carried on its surface passes through the rolling contact portion in one direction. By doing
In a fixing device for fixing the unfixed toner on the sheet, a driving unit for driving the fixing belt endlessly runs, and the driving unit for driving the fixing belt to run at a second running speed during a fixing operation. Control means for controlling, the control means, immediately after power-on,
The driving unit is controlled such that the fixing belt is driven to travel at a first traveling speed lower than the second traveling speed.

According to a fourth aspect of the present invention, in the fixing device, the first traveling speed is controlled by the second traveling speed.
Is set to be equal to or less than 1/2 of the traveling speed of the vehicle.

According to a fifth aspect of the present invention, in the fixing device, the first traveling speed is controlled by the second traveling speed.
Is set to １ ／ to ８ of the traveling speed of the vehicle.

According to a sixth aspect of the present invention, the fixing device of the present invention further comprises a second heat generating means disposed in the pressure roller.

In the fixing device according to the present invention, according to the seventh aspect, the first traveling speed is set to be the same as the speed employed during the fixing operation of the OHP sheet. Features.

In the fixing device according to the present invention, according to the eighth aspect, the first running speed is set to be the same as the speed used during the fixing operation of the thick paper. I have.

In the fixing device according to the present invention, according to the ninth aspect, the first traveling speed is set to be the same as the speed used during the fixing operation of the manual paper. And

According to a tenth aspect of the present invention, in the fixing device according to the tenth aspect, the control means is configured to perform the warm-up operation immediately after power-on until the fixing roller rises to a fixing-possible temperature. The fixing belt is driven to run at a traveling speed of 1 and the fixing roller is driven to travel at the second traveling speed after the fixing roller has been heated to the fixing-possible temperature.

In the fixing device according to the present invention, the control means causes only the first heat generating means to generate heat during the warm-up, so that the fixing roller is capable of fixing. At the time of the fixing operation after the temperature is reached, the first and second heating means are controlled to generate heat.

According to a twelfth aspect of the present invention, in the fixing device according to the twelfth aspect, the amount of heat generated by the first heating means at the time of the warm-up is determined by the first and second heating means at the time of the fixing operation. Is set to a value obtained by summing the calorific values of.

According to a thirteenth aspect of the present invention, the heat generation amount of the first heat generation means at the time of the warm-up is set to be a maximum allowable heat generation amount. The amount of heat generated by the first heat generating means during the fixing operation is set to be smaller than the maximum value.

According to another aspect of the present invention, there is provided a fixing device comprising: a fixing roller; a pressure roller which rolls on the fixing roller at a predetermined pressure; and a distance from the fixing roller. A heating roller in which a first heat generating means is disposed, and the heating roller and the fixing roller are endlessly wrapped around the heating roller, and the fixing roller and the fixing roller receive heat transfer from the first heat generating means. A fixing belt for heating the unfixed toner on the sheet passing through the rolling contact portion of the pressure roller; and a second heat generating means disposed in the pressure roller, the unfixed toner being carried on the surface. The sheet is
In a fixing device for fixing the unfixed toner on the sheet by passing through the rolling contact portion in one direction, the fixing device includes control means for controlling the first and second heat generating means. Means for heating only the first heating means during warm-up from immediately after power-on until the fixing roller rises to a fixing-possible temperature, and a fixing operation after the fixing roller reaches the fixing-possible temperature. In some cases, the first and second heat generating means are controlled so as to generate heat.

According to a fifteenth aspect of the present invention, in the fixing device according to the fifteenth aspect, the amount of heat generated by the first heating means at the time of the warming-up is determined by the first and second heating means at the time of the fixing operation. Is set to a value obtained by summing the calorific values of.

In the fixing device according to the present invention, according to the sixteenth aspect, the heat value of the first heat generating means at the time of the warm-up is a maximum value of the heat value allowed as the fixing device. And the amount of heat generated by the first heat generating means during the fixing operation is set to be smaller than the maximum value.

Further, according to the fixing device of the present invention, according to claim 17, after the fixing roller rises to the fixing-possible temperature, the control means sets the fixing roller at a predetermined second traveling speed. The fixing belt is driven to travel, and at the time of the warm-up, the fixing belt is driven to travel at a first traveling speed lower than the second traveling speed.

According to a twenty-eighth aspect of the present invention, in the fixing device, the first traveling speed is set to be equal to or less than half of the second traveling speed. I have.

In the fixing device according to the present invention, according to claim 19, the first traveling speed is set to １ ／ to ８ of the second traveling speed. It is characterized by.

According to a twentieth aspect of the fixing device according to the present invention, the first traveling speed is OHP.
The speed is set to be the same as the speed used during the fixing operation of the sheet.

According to a twenty-first aspect, in the fixing device according to the present invention, the first traveling speed is set to be the same as the speed employed during a thick paper fixing operation. I have.

According to a twenty-second aspect of the present invention, in the fixing device, the first traveling speed is set to be the same as the speed used during the fixing operation of the manual paper. And

According to a twenty-third aspect of the present invention, in the fixing device, the first heating means includes a first heater for a large size and a second heater for a small size. Wherein the control means causes the first and second heaters to simultaneously generate heat during the warm-up, and selectively causes the first or second heater to generate heat according to the sheet size during the fixing operation. Features.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an embodiment of a fixing device according to the present invention will be described below in detail with reference to the accompanying drawings.

First, as shown in FIG. 1, the fixing device 10 of this embodiment is fixed to an electronic image forming apparatus (not shown) such as a frame of an electronic printer as a housing structure. Housing 1
The housing 12 includes a bottom plate 14 directly fixed on the apparatus frame, side plates 16 standing upright from both left and right side edges of the bottom plate 14, and a substantially upper right portion of the side plate 16 in FIG. And a left cover part 20 attached to the side plate 16 so as to cover substantially the left side thereof.

Here, the upper cover part 18 is fixedly attached to the side plate 16, and at the upper right part thereof,
The swing lever 22 is swingably supported so that the left side in the figure is opened around the first support shaft 24 located on the right side in the figure. On the other hand, the left cover part 20
Is swingably attached to the side plate 16 such that the upper part is opened around the support shaft 26.

The fixing device 10 has a roller configuration in which a fixing roller 28 is rotatably supported on a side plate 16 so as to be rotatable around a fixed axis, and substantially below (specifically, obliquely below) the fixing roller 28. A pressure roller 30 rotatably supported by the side plate 16 around a fixed axis set in parallel with the fixing axis of the fixing roller 28 in a state of being in contact with the roller, and substantially above the fixing roller 28 (specifically, The heating roller 34 is attached to the swing lever 22 in a state where the heating roller 34 is positioned obliquely upward, and is rotatably supported around its own central axis.

The fixing device 10 includes a heating roller 3
4, a first lamp such as a halogen lamp.
And a heat source 32 disposed inside the pressure roller 30.
For example, it further includes a second heat source 33 such as a halogen lamp, and a fixing belt (heat transfer belt) 36 wound endlessly over the fixing roller 28 and the heating roller 34.

Although the details will be described later, the fixing roller 2
Reference numeral 8 denotes an elastic roller, while the pressing roller 30 includes a roller having a higher on-roller hardness than the elastic roller. On the other hand, the fixing roller 28 and the pressure roller 30
As shown in FIG. 2, the distance D between the centers of rotation is slightly smaller than the sum of the radius R1 of the fixing roller 28 and the radius of the pressing roller 30R2 (R1 + R2). As a result, at the mutual rolling contact portion (nip portion) of the fixing roller 28 and the pressing roller 30, the two roll contact each other with a predetermined pressure contact force P 1.
Is brought into a state depressed at the rolling contact portion. That is, a sufficient nip width is secured.

The fixing device 10 includes a fixing belt 3
6, a silicone oil is applied to the outer surface of the fixing belt 36, and an oil applying roller 38 for cleaning the outer surface of the fixing belt 36 is brought into pressure contact with the oil applying roller 38 in a state of being orthogonal to the fixing belt 36. 3
First coil spring 4 for applying predetermined tension to 6
0, and a second coil spring 42 that urges the heating roller 34 in a direction away from the fixing roller 28 and applies a predetermined tension to the fixing belt 36 in cooperation with the first coil spring 40. I have.

The lower right portion of the upper cover 18 in the figure is bent inward, and is located below the bent piece, and is spaced apart from the guide plate 44 by the side of the side plate 16. It is fixed to. From between the upper cover portion 18 and the guide plate 44, a sheet (hereinafter, simply referred to as an unfixed sheet) carrying unfixed toner on the upper surface is moved in one direction (conveying direction) indicated by an arrow in the drawing. An inlet port 46 is defined along the interior of the housing 12.

Here, the guide plate 44 is mounted so as to be inclined upward and leftward in the figure so that the height thereof increases as it enters the housing 12. On the other hand, the leading end of the guide plate 44, that is, the lower right end in the drawing, is an endless sheet transport end disposed in the electronic printer and adjacent to the entrance port 46 on the right side in the drawing. The guide plate 44 is positioned so as to face the outlet end of the belt EB, and the leading end of the guide plate 44, that is, the upper left end in the figure, is a rolling contact portion (nip) between the fixing roller 28 and the pressure roller 30. Part)
Is positioned so as to face the.

The leading end of the unfixed sheet, which has been conveyed through the endless belt EB toward the fixing device 10 in one direction (conveying direction) indicated by an arrow in FIG. , And is guided so as to be conveyed obliquely upward. As a result, the unfixed sheet guided by the guide plate 44 is guided to the rolling contact portion between the fixing roller 28 and the pressure roller 30.

On the other hand, the fixing roller 28 and the pressing roller 30
Thus, a sheet discharge path 48 for discharging a sheet (hereinafter, referred to as a fixed sheet) on which the unfixed toner is fixed by thermocompression bonding is formed. In this embodiment, the sheet discharge path 48 is The fixed sheet is set to be discharged upward in a substantially upright state.

A lower discharge roller 50 is rotatably supported by the left cover 20 in a state positioned between the discharge path 48 and the rolling contact portion. The lower discharge roller 50 is described later. A configuration is adopted in which a driving force from the driving mechanism 52 is obtained and the rotation is performed at a speed equal to or higher than that of the pressure roller 30 (for example, a rotation speed set 5% faster than the speed of the pressure roller 30). Have been. The lower discharge roller 50 includes:
In a state of rolling contact from obliquely above, the upper discharge roller 54 is in rolling contact with the plate spring 56 with a predetermined elastic force. The position of the upper discharge roller 54 is set such that a line connecting the center positions of the upper discharge roller 54 and the lower discharge roller 50 is substantially orthogonal to the discharge path of the fixed sheet. Have been.

In the fixing device 10 having such a schematic configuration, the unfixed sheet S conveyed onto the guide plate 44 via the endless belt EB by the conveying mechanism.
The lower surface where no unfixed toner is attached
The fixing belt 36 is guided toward a rolling contact portion (nip portion) between the fixing roller 28 and the pressure roller 30 around which the fixing belt 36 is wound, and is pressed between the two. It is set so that the unfixed toner is thermocompressed and fixed on the sheet by being inserted.

{Description of Fixing Roller 28} The above-described fixing roller 28 includes a core 28A rotatably supported on a side plate 16 via a bearing (not shown), and a core 28A.
And a roller body 28B coaxially disposed around the outer periphery of the roller A and around which the fixing belt 36 is wound. The roller outer diameter is set to 38.0 mm in this embodiment. Here, in this embodiment, the core 28A has a diameter of 25 mm.
roller body 28B
Is a silicone rubber heat-resistant elastic body attached to the outer periphery of the cored bar 28A with a thickness of 6.5 mm (specifically, JIS
(Silicone rubber having an A hardness of 16 to 17 degrees).

A first driven gear 58 is coaxially mounted on a shaft disposed at one end of the cored bar 28A via a one-way clutch 60, which will be described in detail later. A transmission gear 62 that constitutes a part of the drive mechanism 52, which will be described in detail later, meshes with the one driven gear 58. In this manner, the driving force from the driving mechanism 52 is transmitted to the first driven gear 58 via the transmission gear 62 as a clockwise rotational force in the drawing, and the one-way clutch 60
The rotational force is transmitted to the fixing roller 28 via the fixing roller 28.

{Description of the Pressure Roller 30} As described above, the pressure roller 30 incorporating the second heat source 33 is a core metal part rotatably supported on the side plate 16 via a bearing (not shown). 30A and a roller main body 30B coaxially disposed on the outer periphery of the cored bar 30A, and the roller outer diameter is set to 35 mm. Here, in this embodiment, the core metal part 30A is formed of an iron shaft having a diameter of 32 mm, and the roller main body 30B is formed of the core metal part 3.
Silicone rubber heat-resistant elastic body (specifically, the fixing roller
(Asuka C hardness of 74 to 75 degrees harder than 8)
Is formed from.

The shaft provided at one end of the cored bar 30A has a second driven gear 64 coaxially fixed thereto. The second driven gear 64 is connected to the first driven gear 64 described above. Gear 58
The driving force from this is transmitted to the second driven gear 64 via the first driven gear 58, and the pressing roller 30 moves in the counterclockwise direction opposite to the fixing roller 28. It is configured to be driven to rotate.

In this embodiment, the pressure roller 30 is set as the main drive for conveying the unfixed sheet, and the peripheral speed of the fixing roller 28 is increased even when the fixing roller 28 is thermally expanded. The gear ratio of the first and second driven gears 58 and 64 is set so that the peripheral speed of the pressure roller 30 does not become faster. That is, the rotation speed when the fixing roller 28 is rotated by the second driven gear 64 is the rotation speed of the fixing belt 36.
The rotation speed is set to be slightly lower than the rotation speed at the time of rotation by frictional engagement with the pressure roller 30 through the roller.

On the other hand, in this embodiment, the pressure roller 30 is not located immediately below the fixing roller 28 but is located in the direction of transporting the unfixed sheet rather than immediately below the fixing roller 28. When a vertical line passing through the center point of the fixing roller 28 is set as a base line, the base line is fixed to the fixing roller 28 and the pressing roller 30.
Are arranged so that the angle formed by the line segment passing through the two center points becomes a predetermined acute angle. The pressure roller 3
The line segment defining the center point of 0 is set so as to be substantially perpendicular to the conveying direction of the unfixed sheet.

<< Description of One-Way Clutch 60 >> The one-way clutch 60 allows the fixing roller 28 to rotate relative to the first driven gear 58 in the clockwise direction in FIG. It is configured such that the relative rotation is locked, in other words, both rotate integrally. Specifically, in the cold state, that is, the fixing belt 36 frictionally engages with the pressure roller 30, and the fixing roller 28 frictionally engages with the fixing belt 36, and the fixing roller 28 and the fixing roller 28 are pressed by the pressure roller 30. When the fixing belt 36 is driven (rotated), the peripheral speed of the fixing roller 28 rotating clockwise in the drawing is the same as the peripheral speed of the pressure roller 30, and is lower than the peripheral speed of the first driven gear 58. This speed difference will be absorbed by the one-way clutch 60, although it will be made slightly faster.

The heat generated by the heating roller 34 heats the fixing roller 28 via the fixing belt 36 to be in a warm-up state, and the outer diameter of the fixing roller 28 increases due to thermal expansion, so that the peripheral speed of the fixing roller 28 increases. Even so, the speed difference is set not to be faster than the peripheral speed of the pressure roller 30, so even in this case, the speed difference is reliably absorbed by the one-way clutch 60.

On the other hand, such a one-way clutch 60
Is provided, the following effects are additionally achieved. That is, if such a one-way clutch 60 is not provided, when a glossy sheet such as a coated paper is conveyed to the transfer portion as an unfixed sheet, the unfixed sheet is fixed to the unfixed sheet. Slip occurs between the belt 36 and the driving force of the pressure roller 30, and the driving force of the pressure roller 30 is not transmitted to the fixing belt 36 and the fixing roller 28. When such a situation occurs, the unfixed sheet stops at the transfer portion and jams, or even if the unfixed sheet can pass through the transfer portion, the unfixed toner on the unfixed sheet is stopped. Is rubbed by the fixing belt 36, and the image is disturbed.

However, in this embodiment, the one-way clutch 60 is connected to the fixing roller 28 and the first driven gear 5.
8, even if the driving force of the pressure roller 30 is not transmitted to the fixing belt 36, the rotation speed of the fixing roller 28 is reduced to the first driven gear 58.
When the rotation speed starts to be lower than the rotation speed, the first driven gear 58 is driven to rotate clockwise in the drawing. In this way, the unfixed sheet is reliably passed through the contact portion, and the risk of jamming is effectively prevented, and the unfixed toner image is disturbed when passing through the contact portion. Is suppressed.

{Description of Heating Roller 34} In this embodiment, the heating roller 34 incorporating the first heat source 32 is formed by adding an aluminum pipe core having a diameter of 30 mm and a wall thickness of 3.5 mm to a thickness of 3.5 mm. The bearings at both ends are coated with a 20 μm-thick PTFE coating layer and have a diameter of 34 mm, made of heat-resistant resin made of polyetheretherketone (PEEK).
mm collar 66 is press-fitted, thereby preventing the fixing belt 36 from meandering and offset.

A first heat source 32 is built in the heating roller 34. In this embodiment, the first heat source 32 is provided by a halogen lamp 32 having a maximum output of 1 kW. It is configured. On the other hand, the second heat source 33 built in the above-described pressure roller 30 is constituted by a halogen lamp having a maximum output of 250 W. Here, the maximum output allowed for the heat source of the fixing device 10 is set to 1 kW in this embodiment. That is, in this embodiment, the first heat source 32 is set so as to be able to output the maximum output itself permitted for the fixing device 10.

{Description of the Fixing Belt 36} The fixing belt 36 described above is used to preheat the unfixed toner on the unfixed sheet S to the fixing temperature by radiating heat so that the fixing belt can be fixed without giving an excessive amount of heat. 36 has a heat capacity per square cm of 0.002 cal / ° C to 0.025 c
al / ° C. are preferred. Therefore, in this embodiment, the fixing belt 36 has an inner diameter of 60 m.
m, an endless belt body made of polyimide having a thickness of 100 μm, and a heat-resistant elastic release layer of silicone rubber coated on the outer peripheral surface of the belt body with a thickness of 200 μm.

The fixing belt 36 is not limited to being formed of polyimide and silicone rubber. For example, an endless belt body made of, for example, nickel electroforming of 40 μm and an outer peripheral surface of the belt body are used. And a heat-resistant elastic release layer of silicone rubber coated with a thickness of 200 μm.

{Description of Oil Application Roller 38} The fixing device 10 includes an oil application roller 38 on the outer peripheral surface of the fixing belt 36 for applying a small amount of release oil. Although not shown in detail, the oil application roller 38 includes a support shaft rotatably supported in a fixed state on the casing 68 and a heat-resistant paper layer in which the outer periphery of the support shaft is impregnated with silicone oil. In this embodiment, the support shaft is formed of an iron shaft having a diameter of 8 mm, and the heat-resistant paper layer has a diameter of 100 μm with a porous fluororesin film attached to its outer periphery. 2
It is formed to have a roller outer diameter of 2 mm. By configuring the oil application roller 38 in this way, it is possible to apply a small amount of stable oil to the outer peripheral surface of the fixing belt 36.

The dirt (toner and the like) adhering to the outer peripheral surface of the fixing belt 36 is transferred and adheres to the outer peripheral surface of the oil application roller 38 to be contaminated. Because of this,
A cleaning brush is in contact with the outer peripheral surface of the oil application roller 38.
Is cleaned to remove dirt attached thereto.

{Description of Mechanism for Applying Tension to Fixing Belt 36} As described above, in this embodiment, as a mechanism for applying tension to the fixing belt 36, the oil application roller 38 is perpendicular to the fixing belt 36. A first coil spring 40 for applying a predetermined tension to the fixing belt 36 by pressing the heating roller 34 in a direction away from the fixing roller 28 to cooperate with the first coil spring 40 A second coil spring 42 for applying a predetermined tension to the fixing belt 36.

Here, the first coil spring 40 has a casing 68 that rotatably supports the oil application roller 38.
Is attached to the left cover 20 so as to urge the fixing belt 36 toward the fixing belt 36. That is, the casing 68
The guide rib 70 attached to the side plate 16 supports the fixing belt 36 so as to be able to freely contact and separate from the fixing belt 36. Thus, when the left cover part 20 is opened to the left in the figure,
The first coil spring 40 pressing the casing 68 is separated from the casing 68, whereby the pressing state of the oil application roller 38 against the fixing belt 36 is released. When the left cover portion 20 is rotated rightward in the drawing and closed, the first coil spring 40 presses the casing 68 with the pressing force P2, and the oil application roller 38 applies a predetermined tension to the fixing belt 36. Will be pressed.

On the other hand, the second coil spring 42 is interposed between the left end of the swing lever 22 in the figure and the side plate 16, and in other words, rotates the swing lever 22 clockwise in the figure. Then, the heating roller 3 supported by the swing lever 22
4 is the third pressing force P in the direction in which
3 so as to press it. As a result, a predetermined tension is applied to the fixing belt 36.

That is, the heating roller 34 is biased in a direction away from the fixing roller 28 via the swing lever 22 by the urging force of the second coil spring 42, whereby the heating roller 34 and the fixing roller 28 The fixing belt 36 stretched endlessly is tensioned to a predetermined tension.

As described above, the first and second coil springs 4
The fixing belt 36 frictionally engages with the pressure roller 30 by the action of the fixing belt 36 and rotates, and the fixing roller 28 slips with respect to the fixing belt 36 in accordance with the rotation of the fixing belt 36. It is driven in a stable state without slack.

{Description of Driving Mechanism 52} As shown in FIG. 3, the driving mechanism 52 for rotationally driving the above-described pressure roller 30 and the like is mounted on the electronic printer in a state where the fixing device 10 is mounted. A transmission gear 62 meshes with an output gear GE connected to a drive source on the printer side via a gear train (not shown), and is rotationally driven by receiving a driving force from the output gear GE.
And a first driven gear 58 which is always meshed with the transmission gear 62 and is connected to the fixing roller 28 via the one-way clutch 60, and is always meshed with the first driven gear and A second driven gear 64 fixed coaxially.

The drive mechanism 52 further includes an idle gear 72 that always meshes with the transmission gear 62 described above.
The idle gear 72 always meshes with a third driven gear 74 coaxially fixed to the lower discharge roller 50, and rotates the lower discharge roller 50 at a speed equal to or higher than the peripheral speed of the pressure roller 30. It is configured to be driven.

<< Other Configurations >> In addition to the above-described configuration, the fixing device 10 according to the present embodiment, as shown in FIG. 1, is used to peel off the fixed sheet adhered to the outer peripheral surface of the pressure roller 30 again. The separation claw 76 and the above-described lower discharge roller 50
Paper discharge sensor 78 that detects that the leading end of the fixed sheet has been conveyed between the upper discharge roller 54 and the upper discharge roller 54
And

{Structure of Control System} On the other hand, the fixing device 10 controls the driving of the above-described driving mechanism 52, and is also built in the first heat source 32 built in the heating roller 34 and the pressure roller 30. As shown in FIG. 4, a control device 86 is provided for controlling the heat generation of the second heat source 33.
The control device 86 includes a non-sheet passing portion (that is, a portion of the fixing belt 36 where the unfixed sheet S does not contact) of the fixing belt 36 wound around the outer peripheral surface of the heating roller 34 for the heat generation control described above. ) (Hereinafter, simply referred to as a heating roller temperature).
And a fixing belt 36 wound around the outer periphery of the fixing roller 28.
A second thermistor 82 for detecting the temperature (hereinafter, simply referred to as a fixing roller temperature) Tf of the outer peripheral surface of the paper passing portion (that is, the portion of the fixing belt with which the unfixed sheet S contacts).
Third thermistor 84 that detects the temperature of the outer peripheral surface of pressure roller 30 (hereinafter, simply referred to as pressure roller temperature) Tp.
Are connected, and the first to third thermistors 80 and 8 are connected.
The first and second heat sources 32 and 33 are configured to control the heat generation based on the detection results Th, Tf and Tp from the light sources 2 and 84.

This control device 86 is connected to first and second heater drivers 88A and 88B from the viewpoint of heat generation control, and according to a control procedure described in detail later.
The first heat source 3 is supplied via the first heater driver 88A.
The second halogen lamp of the second heat source 33 is configured to be controlled via the second heater driver 88B. Also, this control device 86
From the viewpoint of running control of the fixing belt 36, an input terminal for receiving a sheet passing command and a power switch 90 are connected, and a drive for causing the fixing belt 36 to run endlessly according to a control procedure described in detail later. The drive of the mechanism 52 is configured to be controlled.

<< Description of Arrangement of Heat Roller 34 >> As described above, in this embodiment, the heat roller 34
Is disposed substantially above the fixing roller 28, so that the endlessly wound fixing belt 36 between the heating roller 34 and the fixing roller 28 and the guide plate 44 The unfixed sheet conveyed above is separated so as not to contact the fixing belt 36. In other words, the fixing belt 36 is
This means that the unfixed sheet conveyed above is disposed at a position outside a region where the unfixed sheet may pass.

As described above, the heating roller 34 is connected to the fixing roller 2
8 above, no matter how the unfixed sheet in the middle of conveyance is in a curved posture (curled state),
The unfixed toner carried on the upper surface of the sheet is reliably prevented from substantially contacting the fixing belt 36 before the fixing operation, and the fixing roller 28 is prevented from disturbing the unfixed toner.
It can be guided to the rolling contact portion between the pressure roller 30 and the pressure roller 30 to fix it.

{Description of Configuration Angle of Heating Roller 34} In the fixing device 10 having the above-described configuration, as described above, the heating roller 34 is disposed substantially above the fixing roller 28 to achieve a specific effect. Can be done.
Here, in order to clearly define the range “approximately above”, as shown in FIG. 5, an experimental example will be described in which the configuration angle of the heating roller 34 is variously changed and the optimum range is obtained.

First, in this experimental example, a perpendicular passing through the center point of the fixing roller 28 is defined as a base line B.
Is defined as θ with respect to a line segment L connecting both center points of the fixing roller 28 and the heating roller 34, the position of the heating roller 34 is changed so that the configuration angle θ becomes 90 ° or more.
At 180 °, the frequency of occurrence of image rubbing at the entrance of the contact portion between the fixing roller 28 and the pressure roller 30 and the frequency of occurrence of abnormalities at the exit of the contact portion are determined during single-sided copying. And at the time of double-sided copying, respectively.

Here, ± of the component angle θ is defined as “+” when the value measured in the counterclockwise direction from the base line B is defined as “+”, and the value measured in the clockwise direction in the figure from the base line B is defined as “−”. Therefore, +1
The heating roller 34 at 80 ° and the heating roller 34 at −180 ° indicate the same position.
The heating roller 34 at 105 ° and the heating roller 34 at −255 ° indicate the same position. on the other hand,
In this embodiment, the abnormality at the outlet of the transfer portion means occurrence of an offset or occurrence of a jam at the outlet of the transfer portion.

The measurement conditions are as follows.

That is, the nip width at the rolling contact portion was set at 8 mm, and the pressing force P1 for this was set at 24 kgf / one side. On the other hand, the temperature of the portion of the fixing belt 36 wound around the fixing roller 28 was set to 160 ° C., and the surface temperature of the pressure roller 30 was set to 140 ° C. Further, the conveyance speed of the unfixed sheet was set to 180 mm / sec, and the pressure roller 30 was rotated in synchronization with the conveyance speed. As the toner, A color toner manufactured by Fuji Xerox Co., Ltd. was used, and as a sheet, plain paper of 64 g / m2 was adopted.

In this manner, the constituent angle θ is set to 90 °, 1
05 °, 120 °, 150 °, 180 °, -150 °,
Divided into nine types of -120 °, -105 °, -90 °
The measurement was performed under the measurement conditions described above.

Table 1 shows the measurement results.

[0080]

[Table 1]

As is clear from Table 1, when the constituent angle θ is larger than 105 ° and smaller than −105 °, that is, when the constituent angle θ is measured only in the counterclockwise direction, When the angle is within the range of from 255 ° to 255 °, there is no occurrence of image rubbing at the entrance of the transfer part and no occurrence of abnormality at the exit of the transfer part, and a good fixing operation is performed. It has been found. On the other hand, when the constituent angle θ is 10
When the angle is 5 ° or less, it was found that either an image rubbing at the entrance of the transfer part or an abnormality at the exit of the transfer part occurred, and good fixing operation was not performed.

{Description of Drive Control and Heat Generation Control Method by Control Device 86} Next, the drive mechanism 52 and the first and second heat sources 3 in the control device 86, which are features of the present invention.
The heat generation control method (control procedure) for the control units 2 and 33 will be described with reference to the flowcharts in FIGS.

Although not shown, this control device 86
A CPU for overall control, a ROM in which programs, thresholds, and set values are stored in advance; an interface circuit for transmitting information to and from a control device of an electronic printer to which the fixing device 10 is mounted; / O port etc.
Schematically, when the power switch 90 is turned on, a warm-up state is defined, a predetermined warm-up control procedure is performed, and a standby state is defined in a state in which no paper passing command is received from the electronic printer. A predetermined standby control procedure is executed, and when a paper passing command is received from the electronic printer, a paper passing state is defined as long as the paper passing command is not terminated, and a predetermined fixing control procedure is executed. It is configured as follows.

More specifically, the control device 86 basically includes (1) immediately after power-on, during warming-up until the fixing roller temperature reaches the feasible fixing temperature T3 during the fixing operation, Only the first halogen lamp as the first heat source 32 is controlled so as to generate heat at its maximum output (1 kW in this embodiment), and the driving mechanism 52 is driven by the fixing belt 36 for the first running. (2) In the standby state, the heating roller temperature is set to a first set value (set temperature) T1 based on the detection result Th of the first thermistor 80 in the standby state. The first heat source 32 is controlled to generate heat with the first output (750 W in this embodiment), and the detection result T of the third thermistor 84 is set such that Based on the pressure roller temperature is second
Of the second heat source 33 so that the set value (set temperature) T2
Is controlled at the second output (250 W in this embodiment), and the drive mechanism 52 is controlled so that the fixing belt 36 does not run. (3) In the sheet passing state, that is, in the fixing operation state, Based on the detection result of the second thermistor 82, the fixing roller temperature is set to the third
The first and second heat sources 32 and 33 are controlled to generate heat at the first and second outputs, respectively, so that the set value (set temperature) T3 of FIG. The drive control is performed so that the sheet travels endlessly at the sheet passing speed V2 as the speed.

Here, in this embodiment, the above-mentioned warming-up speed V1 is 52.5 mm / sec.
In addition, the paper passing speed V2 is set to 210 mm / sec, in other words, the warming-up speed V1
Is set to 1/4 of the paper passing speed V2. The warm-up speed V1 is, in this embodiment,
The setting is made in accordance with the sheet passing speed in the case where an image is formed on an OHP sheet and the image is fixed.

Further, as described above, the first heat source 32 in the fixing operation state generates heat at 750 W.
The second heat sources 33 are each set to generate heat at 250 W. In other words, during the fixing operation, the second heat source 33 outputs the output value of the first heat source 32 during the warm-up and the first heat source 32 during the fixing operation.
Is set to generate heat at an output value corresponding to the difference from the output value of the heat source 32.

Hereinafter, the control procedure in the control device 86 will be described in detail with reference to the flowcharts of FIGS.

{Description of Main Routine of Control Procedure in Control Device 86} First, as shown in FIG.
6 is caused by turning on the power switch 90 (step S1).
0), a predetermined initialization operation is performed and a warm-up control is performed (step S12), and then a standby state control for controlling the heat generation of the first and second heat sources 32 and 33 is performed (step S12). S14). Note that this warm-up control operation will be described later with reference to FIG.
The standby state control operation will be described in detail with reference to FIG.

Then, the standby state control in step S14 is performed until a paper-passing command is received from the electronic printer to which the fixing device 10 is attached (that is, in step S16, Y
Until it is judged as ES), and when a paper passing command comes,
Each drive unit in the drive mechanism 52 is activated to perform drive control in accordance with a predetermined drive control procedure, and execute a paper passing state control for controlling the heat generation of the first and second heat sources 32 and 33 (step S18). . Note that the paper passing state control operation will be described later in detail with reference to FIG.

The paper passing state control in step S18 is executed as long as a paper passing command is received, and when it is detected that the paper passing command has been completed (step S20), the driving of each drive unit in the drive mechanism 52 is performed. Is stopped, and the process returns to step S14 to execute the standby state control.

As described above, the control device 86 controls the drive of the drive mechanism 52 and the first and second heat sources 3.
2, 33 basic heat generation control operations are performed.

{Description of Control Procedure for Warm-Up Control} Next, the control procedure of the warm-up control in step 12 described above will be described in detail as a subroutine with reference to FIG.

When the warming-up control is started, first, the maximum output to the first heat source 32 built in the heating roller 34 (that is, 1 k in this embodiment).
The energization in step W) is started (step S12A), and at the same time as the energization is started, a drive motor (not shown) for driving the drive mechanism 52 is started (step S12B). Here, the rotation speed of the drive motor is set so that the traveling speed of the fixing belt 36 becomes the warming-up speed V1 (52.5 mm / sec in this embodiment) (step S12C).

Then, the surface temperature Tf of the fixing roller 30 is detected via the second thermistor 82 (step S12).
D) If it is determined that the surface temperature Tf of the fixing roller 280 has not yet risen to the feasible temperature T3 (if YES is determined in step S12E), the process returns to step S12C, and thereafter. And waits until the surface temperature Tf of the fixing roller 28 rises.

On the other hand, if it is determined that the surface temperature Tf of the fixing roller 28 has risen to the feasible temperature T3 (if NO is determined in step S12E), this means that the warm-up has been completed. Therefore, the power supply to the first heat source 32 built in the heating roller 34 is temporarily stopped, and the process returns to the original main routine.

As described above, in this embodiment, the warming-up speed V1 of the fixing belt 36 at the time of warming-up is compared with 210 mm / sec which is the paper passing speed V2 of the fixing belt 36 at the time of the fixing operation. 4
, The fixing roller 28 receives sufficient heat transfer from the fixing belt 36 and rises to a feasible temperature T3 within a short time. As a result, the warm-up time is shortened, and This can effectively prevent the user from being irritated, and provide a fixing device that is easy for the operator to use. The above-described verification test for shortening the warm-up time will be described later in detail.

{Explanation of control procedure of standby state control} Next,
The control procedure of the standby state control in step S14 described above will be described in detail as a subroutine with reference to FIG.

When this standby state control is started, first,
The heating roller temperature Th is detected via the first thermistor 80 (step S14A), and the detected temperature Th is set to the first temperature.
It is determined whether the temperature is higher than the set temperature T1 (step S14B). If NO is determined in this step S14B, that is, if the detected temperature Th is equal to the first set temperature T
If it is determined that the temperature is not more than 1, the heating roller temperature has not yet reached the target first set temperature T1, and the first heat source 3 built in the heating roller 34
2 to generate heat (step S14).
C).

On the other hand, if it is determined YES in step S14B, that is, if it is determined that the detected temperature Th is higher than the first set temperature T1, the heating roller temperature is already set to the target temperature. Since the temperature has exceeded the set temperature T1, the power supply to the first heat source 32 built in the heating roller 34 is stopped (step S14).
D).

After the heat generation control for the first heat source 32 built in the heating roller 34 is executed,
The pressure roller temperature Tp is detected via the third thermistor 84 (step S14E), and the detected temperature Tp is changed to the second temperature.
It is determined whether the temperature is higher than the set temperature T2 (step S14F). If NO is determined in this step S14F, that is, if the detected temperature Tp is equal to the second set temperature T
If it is determined that the temperature is not more than 2, the pressure roller temperature T
Since p has not yet reached the target second set temperature T2, the halogen lamp of the second heat source 33 built in the pressure roller 30 is energized to generate heat (step S14G).

On the other hand, if it is determined YES in step S14F, that is, if it is determined that the detected temperature Tp is higher than the second set temperature T2, the pressure roller temperature has already become the target. Since the temperature has exceeded the second set temperature T2, the power supply to the second heat source 33 built in the pressure roller 30 is stopped (step S14H), and the heat generation of the halogen lamp is stopped.

After the heat generation control of the second heat source 33 incorporated in the pressure roller 30 is executed based on the pressure roller temperature Tp, the control procedure is terminated, and the control returns to the original main routine. To return.

{Description of control procedure of paper passing state control}
The control procedure of the sheet passing state control in step S18 will be described in detail as a subroutine with reference to FIG.

When the paper passing state control is started, first,
The output lower than the maximum output to the first heat source 32 built in the heating roller 34 (that is, in this embodiment, 7
50 W) (step S18A), and at the same time as the start of the current supply, a drive motor (not shown) for driving the drive mechanism 52 is started (step S18B).
Here, the rotation speed of this drive motor is
Is the paper passing speed V2 (in this embodiment,
210 mm / sec) (step S18C). Then, the heat generation state of the second heat source 32 built in the pressure roll 30 is changed to 250 W (that is, the output value of the first heat source 32 at the time of warming up, and the first heat source 32 at the time of the fixing operation). (The output value corresponding to the difference from the output value of step S18) (step S18).
D). Here, in step S18D, the same heat generation control operation as the heat generation control of the second heat source 32 performed in steps S14E to 14H in the standby state control described above is executed as a subroutine.

After the control operation for setting the traveling speed of the fixing belt 36 to a speed corresponding to the fixing operation is executed,
The fixing roller temperature Tf is detected via the second thermistor 82 (step S18E), and the detected temperature Tf is changed to the third temperature.
It is determined whether the temperature is higher than the set temperature T3 (step S18F). If NO is determined in this step S18F, that is, if the detected temperature Tf is equal to the third set temperature T
If it is determined that the temperature is not more than 3, the fixing roller temperature has not yet reached the target third set temperature T3.
2 to generate heat according to the size of the sheet (step S18G).

On the other hand, if it is determined YES in step S18F described above, that is, if it is determined that the detected temperature Tf is higher than the third set temperature T3, the fixing roller temperature at which the fixing roller temperature has already reached the target is determined. Since the temperature has exceeded the set temperature T3 of 3, the power supply to the first heat source 32 built in the heating roller 34 is stopped (step S18H), and the heat generation of the halogen lamp is stopped.

As described above, after the heat generation control of the first heat source 32 built in the heating roller 34 is executed based on the fixing roller temperature Tf, this control procedure is terminated, and the process returns to the original main routine. .

As described in detail above, since the control procedure in the control device 86 is configured, the heating roller 34 is activated when the driving mechanism 52 is activated upon receipt of a paper passing command.
The first heat source 32 built in the surface temperature Th of the heating roller 34 which is the measurement result of the first thermistor 80
From the standby state control in which the temperature is controlled to the first set temperature T1 on the basis of the surface temperature Tf of the fixing roller 28, which is the measurement result of the second thermistor 82, to control the temperature to the third set temperature T3. The sheet passing state control operation is switched to the current sheet passing state control, and the sheet passing state control operation is continued as long as the sheet passing command is issued.

As a result, according to this embodiment, in the sheet passing state, the measurement target is not changed in accordance with the detection result of the first thermistor 80 as in the related art, and the fixing roller temperature is always maintained. , The first heat source 32 is controlled, and as a result, the sheet passing speed increases, and a large amount of heat is taken from the fixing roller 28 because the sheet frequently passes through the nip portion. Also, the first heat source 32 is controlled to generate heat, and the calorie of the deprived portion becomes
The heat is supplied (transmitted) from the heating roller 34 to the fixing roller 28 via the fixing belt 36, and the fixing roller temperature is substantially maintained at a fixing-possible temperature. In this manner, even in a high-speed paper passing state, the fixing property is ensured, and a good fixing operation is performed.

Further, in this embodiment, since the second heat source 33 is built in the pressure roller 30 constituting one of the nip portions, a sufficient amount of heat for heating the unfixed sheet S is supplied. As a result, the fixing belt 36
Even if the traveling speed is increased, a sufficient amount of heat can be supplied to the nip portion. In this way, it is possible to sufficiently cope with an increase in the paper passing speed.

In this embodiment, the control device 86 executes the above-described standby temperature control operation to shorten the rise time from the standby time even if the standby time is long. Thus, the effect of shortening the waiting time required until the start of the fixing operation can be obtained.

Further, in this embodiment, the heating roller 34 is disposed substantially above the fixing roller 28, and more specifically, the heating roller 34 is positioned between the center of the heating roller 34 and the fixing roller 28.
When a line segment connecting the center point of the fixing roller 28 and the pressure roller 30 is a line segment connecting the center points of the fixing roller 28 and the pressure roller 30, the angle measured from the base line B is about 105 degrees to about 105 degrees. 25
Since it is disposed at a position within a range of 5 degrees, the space between the fixing belt 36 wound endlessly between the heating roller 34 and the fixing roller 28 and the guide plate 44 passes over the guide plate 44. The conveyed unfixed sheet is separated so as not to contact the fixing belt 36. In other words, this means that the fixing belt 36 is disposed at a position outside an area where the unfixed sheet conveyed on the guide plate 44 may pass.

As a result, according to this embodiment, the unfixed sheet in the middle of conveyance may be in any bending posture (curl state) due to a jump or a slack due to a difference in conveyance speed from the transfer unit. The unfixed toner carried on the upper surface of the sheet is reliably prevented from coming into contact with the fixing belt 36, and the fixing roller 2 is fixed without disturbing the unfixed toner.
8 and the pressure roller 30 can be guided to the rolling contact portion, and this can be reliably fixed.

In this embodiment, the fixing roller 28 is formed from an elastic roller, and the pressure roller 30 is formed so as to have a higher on-roller hardness than the fixing roller. Therefore, according to this embodiment, the fixing roller 28
Even if the size of the pressure roller 30 is reduced, the nip width at the rolling contact portion between the two can be sufficiently ensured, and the size of the fixing device can be reduced.
As a result, it is possible to increase the sheet conveying speed, and it is possible to provide a fixing device particularly suitable for a color printer.

In this embodiment, the upper fixing roller 28 is formed of an elastic roller, and the lower pressing roller 30 is formed of a roller having a higher hardness than the fixing roller 28. Therefore, the shape of the nip at the rolling contact portion is different from the conventional configuration in which the fixing roller is formed from a roller having a higher on-roller hardness than the elastic roller of the present application. It can be easily achieved. As a result, according to this embodiment, from the nip shape itself at the rolling contact portion,
The fixed sheet obtains a force in the direction away from the fixing belt 36, and even if toner is carried on the surface in contact with the fixing belt 36, the oil application roller 38 for preventing offset to the fixing belt 36 , The amount of oil applied can be suppressed to a small amount, and even if oil is not used, an offset to the fixing belt 36 side and a fixing operation without a jam can be achieved.

In this embodiment, a material having a small heat capacity is employed as the fixing belt 36 as the heat transfer belt, and the angle of winding the fixing belt 36 around the heating roller 34 is large. That is, the fixing belt 36 is in close contact. As a result, according to this embodiment, even if the sheet is fed at a high speed, that is, even if the number of sheets passed per unit time is a large number, it is necessary for the fixing operation at the rolling contact portion between the fixing roller 28 and the pressure roller 30. Temperature can be reliably maintained.

In this embodiment, the heat generating source 32 is not provided in the fixing roller 28 as an elastic roller, but the heat generating source 32 is connected to the heating roller 34 disposed at a position separated from the fixing roller 28. Because it was built-in,
The thickness of the silicone rubber heat-resistant elastic body 28B of the fixing roller 28 can be made sufficiently large. As a result, according to this embodiment, the nip width at the rolling contact portion can be maintained at a small diameter for the fixing roller 28. However, it is possible to take a sufficiently wide area.

In this embodiment, the one-way clutch 60 is interposed between the first driven gear 58 and the fixing roller 28, so that the main drive for sheet conveyance (ie, sheet conveyance) is performed. Drive roller that regulates speed)
The pressure roller 30 is set instead of the fixing roller 28. For this reason, for example, the fixing roller 28 is heated with the fixing operation, and as a result, the fixing roller 2
Even if the outer diameter of the sheet 8 thermally expands, the sheet conveying speed is not regulated by the fixing roller 28, so that the sheet conveying speed does not change due to the thermal expansion, and the sheet can always be kept constant. Will be. As a result, according to this embodiment, it is possible to maintain the linear velocity constant and reliably prevent transfer deviation, image rubbing, and the like.

{Verification of warm-up time}
First and second experiments for verifying that the warming-up time is shortened by performing the above-described warming-up control operation in the fixing device 10 having the above-described embodiment configuration are described below. Will be described.

{Description of First Verification Experiment} The configuration of the fixing device 10 used in the first and second verification experiments is the structure of the embodiment described with reference to FIG. The components of the numerical values described in the description of the above are adopted as they are.

In the first verification experiment, the case where the rotation speed of the fixing belt 36 is 210 mm / sec, which is the same value as the paper feeding speed V2 during the fixing operation, is set as a comparative example. 105mm / which is a slower value than
sec (1/2 of paper passing speed V2), 52.5 mm / sec
c (1/4 of paper passing speed V2), 26.25 mm / Sec
(1/8 of paper passing speed V2), 13.13 mm / sec
The warming-up time was measured with four speeds (1/16 of the paper passing speed V2) set as the warming-up speed V1.

Table 2 shows the measurement results.

[0123]

[Table 2]

As is apparent from Table 2, in the first verification experiment, when the fixing belt 36 is driven to run immediately after the power is turned on, the warming-up speed is the same as the sheet passing speed of the ordinary thin sheet. It can be understood that the warming-up time can be remarkably reduced as compared with the comparative example in which is set.

Further, based on Table 2, the relationship between the warm-up speed V1 and the warm-up time is shown in FIG.
0 is shown.

As is apparent from FIG. 10, if the warming-up speed V1 is lower than the sheet passing speed V2, the warming-up speed V1 can contribute to shortening of the warming-up time. If the warming-up speed V1 is set between 1/4 and 1/8 of the sheet passing speed V2, the warming-up time can be significantly reduced. It has been found that it is something that can be achieved. << Description of Second Verification Experiment >> Next, a second verification experiment will be described below.

Fixing device 1 used in the second verification experiment
The configuration of 0 is the structure of the embodiment described with reference to FIG. 1, and the components of the numerical values described in the description of the embodiment are adopted as they are. Note that the rotation speed of the fixing belt 36 is determined by setting the warming-up speed V1 to 60 mm / sec.
And the paper passing speed V2 during the fixing operation is set to 210 mm / sec.
And

[0128] Under the above set conditions, as a first demonstration test in which the maximum output was set to 1 kW, the first heat source 32 was set to 750 W during warm-up.
In addition, a case where each of the second heat sources 33 is heated at 250 W is referred to as a first comparative example, and only the first heat source 32 is set to 1
As a first embodiment, a case where heat is intensively generated at kw is
The warming-up time until the nip rises to the fixing-possible temperature was measured.

As a second verification test in which the maximum output was set to 500 W, the first heat source 32 was set to 250 W and the second heat source 33 was set to 2 W during warm-up.
The case where heat was generated at 50 W each was taken as a second comparative example,
As a second example, a case where only the heat source 32 was heated intensively at 500 W was measured for a warming-up time until the nip portion rises to a fixable temperature.

Further, as a third verification test in which the maximum output was set to 1.5 kW, the first
The heat source 32 is 1 kW, and the second heat source 33 is 5 kW.
The case where heat was generated at 00 W each was taken as a third comparative example,
As a third example, a case where only the heat source 32 was heated intensively at 1.5 kW was measured for a warm-up time until the nip portion was heated to a fixable temperature.

Table 3 shows the measurement results.

[0132]

[Table 3]

As is clear from Table 3, the first heat source 32 built in the heating roller 34 and the second heat source 3 built in the pressure roller 30 during warm-up.
In comparison with the first to third comparative examples in which heat generation is controlled in a state in which the first heat source 32 is dispersed, the first to third heat sources in which only the first heat source 32 incorporated in the heating roller 34 are concentrated are controlled. It is understood that the embodiment of the present invention significantly shortens the warm-up time.

Further, based on Table 3, the relationship between the warm-up speed V1 and the warm-up time is shown in FIG.
It is shown in FIG.

As is apparent from FIG. 11, the warm-up time is shortened in proportion to the magnitude of the maximum power, and as described above, the first and second heat sources 3
It has been found that the warming-up time can be shortened more by intensively heating the first heat source 32 than by dispersing the heat into the first and second heat sources 32 and 33.

The power that can be consumed by the fixing device 10 depends on the power distributed from the image forming apparatus provided with the fixing device 10, and cannot be specified by the fixing device itself. However, it is understood from the above verification that the warming-up time can be reduced by setting the power distributed from the image forming apparatus as large as possible. Further, it is also understood that the power distributed from the image forming apparatus is intensively consumed by the first heat source 32 during the warming-up and the heat is generated, whereby the warming-up time can be effectively shortened.

[0137]

[Explanation of Modifications] It is needless to say that the present invention is not limited to the configuration of the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

For example, in the above-described embodiment, the case where the fixing device 10 is applied to an electronic printer has been described. However, the present invention is not limited to such an application, and an electronic facsimile device, It goes without saying that the present invention can be applied to an electronic image forming apparatus such as an electronic copying apparatus.

Further, in the above-described embodiment, the unfixed sheet has been described as being conveyed to the fixing device 10 from the lateral direction. The landing sheet may be configured to be conveyed in a vertical direction, for example, from bottom to top. In this case, the pressure roller 30 is not below the fixing roller 28,
Needless to say, the heating roller 34 is disposed on the side of the fixing roller 28 opposite to the side on which the pressure roller 30 is disposed. .

In the above-described embodiment, the temperature of the belt on each roller is measured and used for controlling the heater. However, the surface temperature of each roller is directly measured and the heating source is measured. 32 (33) can also be used.

In the above-described embodiment, the control operation at the time of warming-up is described as the fixing belt 36 is driven to run when the power is turned on, that is, immediately after the power is turned on. The fixing belt 36 is not driven to run until the surface temperature of the heating roller 34 reaches a predetermined target temperature after the power is turned on and reaches the predetermined target temperature. Only after that, the fixing belt 36 may be configured to be driven to travel. By starting the running of the fixing belt 36 with a delay immediately after the power is turned on, the warming-up time can be further reduced.

In the above-described embodiment, the first traveling speed V1 as the warming-up speed is equal to O
Although the description has been made so as to match the sheet passing speed when fixing the HP sheet, the sheet passing speed used when fixing the OHP sheet is usually a sheet made of ordinary thin paper. The fixing speed is set to be lower than the paper passing speed V2 in the case of fixing, and this is utilized. The present invention is not limited to such a setting, and the fixing of a sheet made of ordinary thin paper is performed. If it is set lower than the speed V2, it can be set freely. For example, when passing thick paper, it is slower than the speed V2 when passing a sheet made of ordinary thin paper. If set, the speed at which this cardboard passes
It may be adopted as the warming-up speed V1,
Also, when the sheet is manually fed, if the speed V2 is set to be lower than the speed V2 for passing a sheet made of ordinary thin paper, the speed for passing the manually fed sheet is used. May be adopted as the warming-up speed V1.

In the above-described embodiment, the first
Although the heat source 32 has been described as being composed of one heater, specifically, a halogen lamp, the present invention is not limited to such a configuration, and the heat source 32 can be used as a first heater for a large size. And a halogen lamp as a second heater for a small size may be built in the heating roller 34 together.

In this case, at the time of warming-up, when the first heat source 32 generates heat intensively at the maximum output, the first and second halogen lamps are simultaneously energized to generate heat, and the fixing operation is performed. When the first heat source 32 generates heat at an output lower than the maximum output,
Depending on the size of the sheet to be passed, the first and second halogen lamps may be selectively energized to selectively generate heat.

[0145]

As described above in detail, according to the present invention, the warming-up time immediately after the power is turned on can be reduced by intensively heating the first heat source incorporated in the heating roller at the time of warming-up. Thus, a fixing device that can be operated is provided. Further, a fixing device capable of maximally shortening a warm-up time immediately after the power is turned on by providing the first heat source with heat at its maximum output is provided.

[0146]

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a configuration of an embodiment of a fixing device according to the present invention.

FIG. 2 is a diagram illustrating a rolling contact state between a fixing roller and a pressure roller.

FIG. 3 is a front view showing a configuration of a driving mechanism.

FIG. 4 is a block diagram showing a system configuration for drive control of a drive mechanism and temperature control of a heat source.

FIG. 5 is a diagram illustrating a configuration angle in an experimental example performed to check an allowable range of an arrangement position of a heating roller with respect to a fixing roller.

FIG. 6 is a flowchart showing a main routine of a control procedure for controlling a heat source in the control device.

7 is a flowchart showing a subroutine of warming-up control in the main routine shown in FIG. 6;

FIG. 8 is a flowchart showing a subroutine of standby state control in the main routine shown in FIG. 6;

FIG. 9 is a flowchart showing a subroutine for paper passing state control in the main routine shown in FIG. 6;

FIG. 10 is a diagram illustrating a relationship between a warming-up speed and a warming-up time of a fixing belt in a first verification experiment.

FIG. 11 is a diagram illustrating a relationship between a heating state of a heat source of a fixing belt and a warm-up time in a second verification experiment.

FIG. 12 is a front view schematically showing a configuration of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixing apparatus 12 Housing 14 Bottom plate 16 Side plate 18 Upper cover part 20 Left cover part 22 Swing lever 24 First support shaft 26 Second support shaft 28 Fixing roller 28A Core part 28B Roller main body 30 Pressure roller 30A Core metal Unit 30B Roller body 32 First heat source 33 Second heat source 34 Heating roller 36 Fixing belt 38 Oil application roller 40 First coil spring 42 Second coil spring 44 Guide plate 46 Inlet port 48 Paper discharge path 50 Lower paper discharge Roller 52 Drive mechanism 54 Upper paper discharge roller 56 Leaf spring 58 First driven gear 60 One-way clutch 62 Transmission gear 64 Second driven gear 66 Collar 68 Casing 70 Guide rib 72 Idle gear 74 Third driven gear 76 Peeling claw 78 Discharge Paper sensor 80 First thermistor 82 Second thermistor Motor 84 third thermistor 86 control device 88A first heater driver 88B second heater driver 90 the power switch EB endless belt GE output gear S unfixed sheet

Claims (23)

[Claims] A fixing roller, a pressure roller which is in contact with the fixing roller at a predetermined pressure, and a heating roller which is disposed apart from the fixing roller and has first heat generating means disposed therein. The unfixed toner on the sheet, which is endlessly wrapped around the heating roller and the fixing roller, receives heat transfer from the first heating means and passes through the rolling contact portion of the fixing roller and the pressure roller. A fixing belt which heats the unfixed toner on the sheet by passing the unfixed toner on the surface thereof in one direction through the rolling contact portion. A driving unit for causing the fixing belt to run endlessly; and a control unit for controlling the driving unit so that the fixing belt runs at a second running speed during a fixing operation. The means controls the driving means so that the first time the fixing belt runs after power-on, the fixing belt is driven to run at a first running speed lower than the second running speed. Fixing device. 2. A fixing roller, a pressure roller which rolls in contact with the fixing roller at a predetermined pressure, and a heating roller which is disposed apart from the fixing roller and has first heat generating means disposed therein. The unfixed toner on the sheet, which is endlessly wrapped around the heating roller and the fixing roller, receives heat transfer from the first heating means and passes through the rolling contact portion of the fixing roller and the pressure roller. A fixing belt which heats the unfixed toner on the sheet by passing the unfixed toner on the surface thereof in one direction through the rolling contact portion. A driving unit for causing the fixing belt to run endlessly; and a control unit for controlling the driving unit so that the fixing belt runs at a second running speed during a fixing operation. Means, with the power on, the fixing belt fixing device and controls the drive means so as to run driven by the slower than the second speed first running speed. 3. A fixing roller, a pressure roller which rolls on the fixing roller at a predetermined pressure, and a heating roller which is disposed apart from the fixing roller and has first heating means disposed therein. The unfixed toner on the sheet, which is endlessly wrapped around the heating roller and the fixing roller, receives heat transfer from the first heating means and passes through the rolling contact portion of the fixing roller and the pressure roller. A fixing belt which heats the unfixed toner on the sheet by passing the unfixed toner on the surface thereof in one direction through the rolling contact portion. A driving unit for causing the fixing belt to run endlessly; and a control unit for controlling the driving unit so that the fixing belt runs at a second running speed during a fixing operation. Means, immediately after power-on, the fixing device, characterized in that said fixing belt to control the driving means so as to run driven by the slower than the second speed first running speed. 4. The fixing device according to claim 1, wherein the first traveling speed is set to be equal to or less than の of the second traveling speed. 5. The fixing device according to claim 4, wherein the first traveling speed is set to be １ ／ to ８ of the second traveling speed. 6. The fixing device according to claim 1, further comprising a second heat generating means disposed in the pressure roller. 7. The fixing device according to claim 1, wherein the first running speed is set to be the same as a speed used during a fixing operation of the OHP sheet. 8. The fixing device according to claim 1, wherein the first traveling speed is set to be the same as a speed employed during a fixing operation of thick paper. 9. The fixing device according to claim 1, wherein the first running speed is set to be the same as a speed used in a fixing operation of a manual sheet. 10. The control unit causes the fixing belt to run at the first running speed during warm-up immediately after power-on until the fixing roller rises to a fixing-possible temperature. 2. The fixing device according to claim 1, wherein after the temperature is raised to the fixing-possible temperature, the fixing belt is driven to run at the second running speed. 3. 11. The control means causes only the first heat generating means to generate heat during the warming-up, and performs the first and second heating operations during a fixing operation after the fixing roller has reached the fixable temperature. The fixing device according to claim 10, wherein the heating unit is controlled to generate heat. 12. The heating value of the first heating means at the time of the warming-up is set to a value obtained by summing the heating value of the first and second heating means at the time of the fixing operation. The fixing device according to claim 11. 13. The heating value of the first heating means at the time of the warming-up is set to be a maximum value of an allowable heating value, and the heating value of the first heating means at the time of the fixing operation is: The fixing device according to claim 11, wherein the fixing device is set to a value smaller than the maximum value. 14. A fixing roller, a pressure roller which rolls in contact with the fixing roller at a predetermined pressure, and a heating roller which is disposed apart from the fixing roller and has first heat generating means disposed therein. The unfixed toner on the sheet, which is endlessly wrapped around the heating roller and the fixing roller, receives heat transfer from the first heating means and passes through the rolling contact portion of the fixing roller and the pressure roller. A fixing belt to be heated, and a second heat generating means disposed in the pressure roller,
A fixing device for fixing the unfixed toner on the sheet by passing the sheet having the unfixed toner carried on the surface thereof in one direction through the rolling contact portion, wherein the first and the second A control unit for controlling the heat generating unit, the control unit causes only the first heat generating unit to generate heat during warm-up immediately after power-on until the fixing roller rises to a fixing-possible temperature; A fixing device, wherein during a fixing operation after the fixing roller has reached the fixable temperature, the first and second heat generating units are controlled to generate heat. 15. The heating value of the first heating means at the time of the warming-up is set to a value obtained by summing the heating value of the first and second heating means at the time of the fixing operation. The fixing device according to claim 14. 16. The heat generation amount of said first heat generation means at the time of said warming-up is set to be a maximum value of heat generation amount permitted as a fixing device, and said heat generation amount of said first heat generation means during said fixing operation. The fixing device according to claim 14, wherein the amount is set to be smaller than the maximum value. 17. The control unit according to claim 1, wherein after the temperature of the fixing roller is raised to the feasible temperature, the fixing belt is driven to run at a predetermined second running speed. The fixing device according to claim 14, wherein the fixing belt is driven to run at a first running speed lower than the running speed. 18. The fixing device according to claim 17, wherein the first traveling speed is set to be equal to or less than half of the second traveling speed. 19. The fixing device according to claim 18, wherein the first traveling speed is set to be 1/4 to 1/8 of the second traveling speed. 20. The fixing device according to claim 17, wherein the first running speed is set to be the same as a speed used during a fixing operation of the OHP sheet. 21. The fixing device according to claim 17, wherein the first running speed is set to be the same as a speed used during a fixing operation of thick paper. 22. The fixing device according to claim 17, wherein the first running speed is set to be the same as a speed used during a fixing operation of a manual paper. 23. The first heating means includes a first heater for a large size and a second heater for a small size, and the control means includes a first heater and a second heater for warming up. Simultaneously generate heat, and during the fixing operation,
15. The fixing device according to claim 14, wherein the first or second heater selectively generates heat according to a sheet size.