JP2001175115A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of performing the preferential control of a heating source without damaging the surface of a fixing belt. SOLUTION: This fixing device is equipped with a controller for controlling the heating state of the heating source 32 based on the detected result by 1st and 2nd temperature sensors 80 and 82. In the device, a sheet on the surface of which unfixed toner is carried is made to pass through a rolling part in one direction, so that the unfixed toner is fixed on the sheet. At least either the 1st or the 2nd temperature sensor is equipped with a non-contact type temperature sensor, and the controller controls the calorific value of the heating source 32 so that the temperature of a heating roller may be 2nd set temperature when the detected result by the 1st temperature sensor is below 1st set temperature T1, and controls the calorific value of the heating source 32 so that the temperature of the fixing roller may be the temperature T1 when the detected result by the 1st temperature sensor is equal to or above the temperature T1.

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 recent years, a fixing device for an electrophotographic apparatus has a fixing roller R1 and a heat source H as shown in FIG.
The fixing belt B is stretched endlessly between the heating roller R3 and the pressure fixing roller R2 that presses from below through the fixing belt B. The combined technology has been developed and put into practical use. In this conventional configuration, the temperature of the nip portion can be set low by preheating, and by using the fixing belt B having a small heat capacity, the temperature of the fixing belt B is rapidly cooled when passing through the nip portion. By increasing the cohesive force of the toner that separates from the toner, the releasability of the fixing belt B and the toner is enhanced, and a clear fixed image without offset can be obtained even when no oil or a small amount of oil is applied. Become. This belt-type fixing device is known as a fixing device that at once has solved the problems of releasability and oil application that could not be solved by the heating roller method.

In this type of conventional belt-type fixing device, as shown in, for example, Japanese Patent Application Laid-Open No. H10-115996, a heat source is removed from the fixing roller R1 and incorporated in a heating roller R3. Therefore, heat from the heating roller R3 is transferred to the fixing roller R1 via the fixing belt B.
To the rolling contact portion (nip) between the pressure roller R2 and the pressure roller R2. Then, in order to maintain the fixability as a temperature at the transfer contact portion as a fixing temperature, the heating roller R is adjusted so that the temperature at the transfer contact portion becomes the fixing temperature.
The heat generation state of the heat source H built in 3 must be controlled. In particular, in the above-mentioned Japanese Patent Application Laid-Open No. 10-115996, so-called priority control is performed so that a jam does not occur at the time of fixing thin paper, and at the same time, a copy speed does not decrease even if such measures are taken. It has been implemented.

Here, a first temperature sensor S1 for detecting the surface temperature of the heating roller R3 and a fixing roller R
The second temperature sensor S2 for detecting the surface temperature of
Each is arranged. When an auxiliary heater as an auxiliary heat source is provided in the pressure roller R3, a third temperature sensor S3 is provided for detecting the surface temperature of the pressure roller R3. And the control device:
The heating state of the heater H is controlled based on the detected temperature information from the first and second temperature sensors S1 and S2.

[0005]

However, contact type sensors are used as the temperature sensors S1, S2 and S3. For example, if attention is paid to the temperature sensor S1, this is always the outer peripheral surface of the heating roller R2. The fixing belt B is wound so as to be in contact with the fixing belt B.
As a result, with the endless running of the fixing belt B, the tip of the temperature sensor S1 always comes into sliding contact with the surface of the fixing belt B, which may damage the surface of the fixing belt B, which is not preferable. Also, a contact-type sensor is used for the temperature sensor S2, and the same problem occurs.

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 executing priority control of a heating unit without damaging the surface of a fixing belt. It is.

[0007]

Means for Solving the Problems To solve the above-mentioned problems,
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. And a heating roller having a heating means disposed therein, and endlessly wrapped around the heating roller and the fixing roller, and receiving heat from the heating means to rotate the fixing roller and the pressure roller. A fixing belt for heating the unfixed toner on the sheet passing through the contact portion, first temperature detecting means for detecting the temperature of the fixing roller, second temperature detecting means for detecting the temperature of the heating roller, Control means for controlling the heat generation state of the heat generation means based on the detection results of the first and second temperature detection means, wherein the sheet having unfixed toner carried on its surface moves the transfer contact portion in one direction. Along By doing so, in a fixing device for fixing the unfixed toner on the sheet, at least one of the first and second temperature detecting means includes a non-contact type temperature sensor, and the control means When the detection result of the temperature detecting means is lower than the first set temperature, the amount of heat generated by the heat generating means is controlled so that the surface temperature of the heating roller becomes the second set temperature, and the first temperature is controlled. When the detection result of the detecting means is equal to or higher than the first set temperature, the amount of heat generated by the heat generating means is controlled so that the surface temperature of the fixing roller becomes the first set temperature. .

According to a second aspect of the present invention, there is provided a fixing device, wherein the first temperature detecting means is a non-contact type which is disposed so as to face the outer peripheral surface of the fixing roller. It is characterized by having a temperature sensor.

Further, in the fixing device according to the present invention, according to the third aspect of the present invention, the first temperature detecting means is disposed so as to face the fixing belt portion on the fixing roller while being spaced apart from the fixing belt. It is characterized by having a contact-type temperature sensor.

According to a fourth aspect of the present invention, the first temperature detecting means is located downstream of the fixing roller with respect to a running direction of the fixing belt. And a non-contact type temperature sensor disposed so as to be spaced apart and opposed to a portion of the fixing belt located upstream of the heating roller with respect to the running direction.

According to a fifth aspect of the present invention, in the fixing device according to the fifth aspect, the second temperature detecting means is provided in a non-contact type in which the second temperature detecting means is disposed so as to face the outer peripheral surface of the heating roller. It is characterized by having a temperature sensor.

Further, in the fixing device according to the present invention, according to the sixth aspect, the second temperature detecting means is disposed so as to be separated from and opposed to a portion of the fixing belt on the heating roller. A non-contact temperature sensor is provided.

According to a seventh aspect of the present invention, the second temperature detecting means is located downstream of the heating roller with respect to a running direction of the fixing belt. And a non-contact type temperature sensor disposed so as to be separated from and opposed to a portion of the fixing belt located upstream of the fixing roller in the running direction.

According to the fixing device of the present invention, the non-contact type temperature sensor detects infrared rays radiated from the detected portion and detects the surface temperature of the detected portion. It is characterized by non-contact detection.

According to a ninth aspect of the present invention, in the fixing device according to the ninth aspect, the pressure roller is provided with an auxiliary heating means for heating the pressure roller, and the surface temperature of the pressure roller is reduced. It is characterized by further comprising third temperature detecting means for detecting.

According to a tenth aspect of the present invention, in the fixing device, the third temperature detecting means includes a non-contact type temperature sensor.

[0017]

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 a frame of an electronic image forming apparatus (not shown) such as 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 portion 18 is fixedly attached to the side plate 16, and at the upper right portion 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.

Further, the fixing device 10 has a fixing roller 28 rotatably supported on a side plate 16 around a fixed axis, and a roller 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
A fixing belt (heat transfer belt) 36 endlessly wound around a first heat source 32 such as a halogen lamp as a heat generating means, and a fixing roller 28 and a heating roller 34 disposed inside the fixing roller 4. And further provided.

Here, although the details will be described later, the fixing roller 2
8 is configured as an elastic roller, while the pressure roller 30
Is composed of a roller having a higher on-roller hardness than the elastic roller. On the other hand, the fixing roller 28 and the pressure roller 3
As shown in FIG. 2, the distance D between the centers of rotation with respect to 0 is
The radius is set slightly but shorter than the sum (R1 + R2) of the radius R1 of the fixing roller 28 and the radius of the pressing roller 30R2. As a result, at the mutual rolling contact portion (nip portion) of the fixing roller 28 and the pressure roller 30, the two roll contact each other with a predetermined pressure contact force P <b> 1, whereby the fixing roller 2
8 will be brought into a concave state 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 separated from the side by a large distance from the guide plate 44. 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 attached in such a manner as to be inclined upward and leftward in the figure so that its height 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 conveyed through the endless belt EB toward the fixing device 10 in one direction (conveying direction) indicated by an arrow in FIG. The unfixed sheet guided by the guide plate 44 is set so that it is conveyed obliquely upward, and the leading end of the unfixed sheet first contacts the outer peripheral surface of the pressure roller 30. The fixing roller 28 is configured to move along the outer peripheral surface of the pressure roller 30 and to be guided to a 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 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. It is set so that the unfixed toner is thermocompressed and fixed on the sheet by being inserted.

Hereinafter, the various components described above will be sequentially described individually. << Description of the fixing roller 28 >>
A core 28A is rotatably supported on the side plate 16 via a bearing (not shown), and a roller body 28B is disposed coaxially around the core 28A 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 metal core 28A is formed of an iron shaft having a diameter of 25 mm, and the roller body 28B is
A silicone rubber heat-resistant elastic body attached to the outer periphery of A with a thickness of 6.5 mm (specifically, JIS A
(18 degrees in hardness).

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.

{Explanation of the Pressure Roller 30} As described above, the pressure roller 30 includes a core 30A rotatably supported on the side plate 16 via a bearing (not shown), and the core 30A of the core 30A. Roller body 30 disposed coaxially on the outer periphery
B, and the roller outer diameter is set to 35 mm. Here, in this embodiment, the core metal part 30
A is formed from an iron pipe having an inner diameter of 22 mm and an outer diameter of 32 mm, and the roller body 30B has a silicone rubber heat-resistant elastic body attached to the outer periphery of the cored bar portion 30A with a thickness of 1.5 mm (specifically, the fixing member described above. A roller having an ASKER C hardness of 74 to 75 degrees on a roller harder than the roller 28).

A 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 a direction in which the unfixed sheet is conveyed below the position immediately below the fixing roller 28. When a line segment passing through both center points of the heating roller 34 and the fixing roller 28 is set as a base line, the base line and the fixing roller 2
8 and the pressure roller 30 are disposed at such a position that an angle formed by a line segment passing through both center points thereof becomes a predetermined acute angle.
A line segment passing through both center points of the fixing roller 28 and the pressure roller 30 is set so as to be substantially orthogonal 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 the figure, but in the counterclockwise direction in the figure. It is configured such that the relative rotation is locked, in other words, both rotate integrally. That is, the fixing belt 36 is
And the fixing roller 28 is fixed to the fixing belt 3.
6 is frictionally engaged with the fixing roller 2 by the pressure roller 30.
8 and the fixing belt 36 are driven (rotated), the peripheral speed of the fixing roller 28 rotating clockwise in the drawing is:
The rotation speed of the fixing roller 28 is set to be slightly faster than the rotation of the first driven gear 58 because the rotation speed of the fixing roller 28 is equal to the peripheral speed of the pressure roller 30.

{Description of Heating Roller 34} The heating roller 34 incorporating the first heat source 32 described above is, in this embodiment, provided with a 30 mm diameter, 3.5 mm thick aluminum pipe core bar. 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).
The collar 66 of mm is inserted to prevent the fixing belt 36 from meandering and leaning.

A first heat source 32 as heat generating means is built in the heating roller 34. In this embodiment, the first heat source 32 has a maximum output of 1 kW. It comprises a halogen lamp 32. On the other hand, the above-described pressure roller 30 has a second heat source 33 built therein as auxiliary heat generating means. The second heat source 33 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 Fixing Belt 36} The fixing belt 36 has a size of one square cm of the fixing belt 36 so that the unfixed toner on the unfixed sheet S can be fixed to the fixing temperature without applying an excessive amount of heat. Heat capacity per unit is 0.
Those in the range of 002 cal / ° C to 0.025 cal / ° C are preferred. Therefore, in this embodiment, as shown in FIG. 4, the fixing belt 36 has an endless belt base 36a made of polyimide resin having an inner diameter of 60 mm and a thickness of 100 μm, and an outer peripheral surface of the belt base 36a. (A surface layer) and a heat-resistant elastic release layer 36b of silicone rubber coated with a thickness of 200 μm.

In this embodiment, the outer peripheral surface of the belt base 36a is coated with the heat-resistant elastic release layer 36b.
The release layer is not limited to the above-mentioned coating, but may have a heat-resistant layer, and is not necessarily required to have elasticity. That is, the outer peripheral surface of the belt base 36a is set to be coated with the heat-resistant release layer 36b at a minimum.

{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 5 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.

On the outer peripheral surface of the oil application roller 38, dirt (toner and the like) adhering to the outer peripheral surface of the fixing belt 36 is transferred and adheres, and is contaminated. For this reason, a cleaning brush is in contact with the outer peripheral surface of the oil application roller 38, so that the outer peripheral surface of the oil application roller 38 is constantly 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 Drive Mechanism 52 >> The drive mechanism 52 for rotatingly driving the above-described pressure roller 30 and the like is provided with the fixing device 10 mounted on an electronic printer as shown in FIG. 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 80 that always meshes with the transmission gear 62 described above.
The idle gear 80 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 has a configuration in which a fixed sheet adhered to the outer peripheral surface of the pressure roller 30 comes out again as shown in FIG. A paper discharge detecting unit detects that the leading end of the fixed sheet has been conveyed between the lower paper discharge roller 50 and the upper paper discharge roller 54 (rotational contact part) and a peeling claw 76 for peeling off the paper. And a sensor 78.

{Configuration 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. 5, a control device 86 is provided for controlling the heat generation of the second heat source 33.
In this embodiment, the controller 86 detects the temperature of the fixing belt 36 on the fixing roller 28 (hereinafter, simply referred to as a fixing roller temperature) for controlling the heat generation of the first heat source 32. A first temperature sensor 80 is connected to a second temperature sensor 82 for detecting the temperature of the fixing belt 36 on the heating roller 34 (hereinafter, simply referred to as a heating roller temperature). For controlling the heat generation of the source 33,
The temperature of the surface (outer peripheral surface) of the pressure roller 30 (hereinafter simply referred to as
It is called the pressure roller temperature. 3) is connected.

Then, the control device 86 performs the following based on the detection results from the first and second temperature sensors 80 and 82.
The first heat source 32 is configured to control heat generation, and the second heat source 33 is configured to control heat generation based on a detection result from the third temperature sensor 84.

Here, in this embodiment, each of the first to third temperature sensors 80, 82 and 84 is constituted by a non-contact type temperature sensor.
An NC sensor (trade name) manufactured by Ishizuka Electronics Co., Ltd. is used. Thus, the first to third temperature sensors 80, 8
Since both 2 and 84 are constituted by non-contact type temperature sensors, the fixing belt 36 is reliably prevented from being damaged by these temperature sensors.

The first non-contact type temperature sensor 80
As shown in FIG. 1, is disposed so as to be spaced apart from and facing the fixing belt 36 on the fixing roller 28, and is configured to detect the temperature of the fixing roller in a non-contact state. Further, the second non-contact temperature sensor 82 is disposed so as to be separated from and opposed to the fixing belt 36 on the heating roller 34, and is configured to detect the temperature of the heating roller in a non-contact state.
Further, the third non-contact temperature sensor 84 is provided with the pressure roller 3.
The pressure roller is disposed so as to be opposed to the outer peripheral surface of the pressure roller 0 and is configured to detect the pressure roller temperature in a non-contact state.

From the viewpoint of heat generation control, the control device 86 described above controls the first and second heater drivers 88 and 90.
Are connected, and a first heat source 32 as a first heat source 32 is connected through the first and second heater drivers 88 and 90.
Of the second halogen lamp as the second heat source 33 and the second halogen lamp. In addition, from the viewpoint of running control of the fixing belt 36, the control device 86 is connected to an input terminal for receiving a sheet passing command and a power switch 90, and controls the driving mechanism 52 for causing the fixing belt 36 to run endlessly. It is configured to drive control.

{Description of Heat Generation Control Method by Control Device 86} Next, the first heat source 32 in the control device 86
Priority control method (control procedure) will be described.

First, basically, assuming that the set value of the fixing roller temperature is T1 and the set value of the heating roller temperature is T2,
The amount of heat generated by the first heat source 32 is controlled such that the fixing roller temperature and the heating temperature become the set values T1 and T2, respectively.

In the normal standby state, the fixing roller temperature is equal to or lower than the first set value T1, and based on the detection result of the second non-contact type temperature sensor 82 for detecting the heating roller temperature, the control device 86 The amount of heat generated by the first heat source 32 is controlled such that the temperature of the heating roller becomes the second set value T2.

Thereafter, when the fixing belt 36 runs endlessly, the fixing roller 28 and the pressure roller 30 are warmed by the heat transfer of the fixing belt 36, and the fixing roller temperature and the pressure roller temperature rise, respectively. Then, when the fixing roller temperature reaches the set value T1, the control mode is switched, and
The amount of heat generated by the first heat source 80 is controlled so that the fixing roller temperature becomes the first set value T1 based on the detection result of the first non-contact temperature sensor 80.

Even if the fixing roller temperature is equal to or higher than the first set value T1 immediately after the endless running of the fixing belt 36 is stopped, the detection result of the first non-contact type temperature sensor 80 is similarly obtained. The amount of heat generated by the first heat source 80 is controlled so that the fixing roller temperature becomes the first set value T1 based on the temperature.

Here, after the fixing belt 36 stops,
The fixing roller temperature gradually decreases and becomes lower than the first set value T1. Then, the control mode is switched again in the control device 86, and based on the detection result of the second non-contact type temperature sensor 82, the heat generation of the first heat source 80 is set so that the heating roller temperature becomes the second set value T2. The amount is controlled.

In this way, from the standby state until the fixing roller temperature reaches the first set value T1, the heating roller temperature is preferentially managed with the second set value t2 as the target value and controlled. When the temperature of the fixing roller reaches the first set value T1, the first heat source 80 controls the temperature of the fixing roller with priority given to the first set value T1 as a target value. Will be executed.

FIG. 6 shows temperature characteristics when the priority control method of this embodiment is executed. In FIG.
The horizontal axis shows the rotation time of the fixing belt, and the vertical axis shows the temperature of each roller. The wavy line W shown in the practice of the information in FIG. 6 indicates the temperature of the heating roller, and the characteristic curve C
Indicates a change in the fixing roller temperature.

The temperature characteristics will be described below with reference to FIG. From the standby time, until the fixing roller temperature rises and reaches the first set value T1, the heating roller temperature is controlled to be the second set value as in the related art. When the fixing roller temperature reaches the first set value T1, the control mode is switched, and the fixing roller temperature is reduced to the first set value T1.
Since the amount of heat generated by the first heat source 80 is controlled so as to be 1, the fixing roller temperature does not rise above the first set value T1 (fixing upper limit temperature), and offset and thin paper jam occur. There is no danger.

Here, the fixing roller temperature is set to the first set value T.
After the amount of heat generated by the first heat source 80 is controlled to be 1, the temperature of the heating roller will be reduced lyrically.
Since the pressure roller temperature curve (C ') rises to compensate for the decrease in the temperature of the heating roller, there is no problem in the fixing property of the apparatus.

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 fixing belt 36 has been described as including the belt body 36a made of polyimide resin. However, the present invention is not limited to such a configuration, and the present invention is not limited thereto. As described in the section, it goes without saying that a nickel electroformed belt can be used.

In the above-described embodiment, the second heat source 33 is incorporated in the pressure roller 30. However, the present invention is not limited to such a structure.
Needless to say, the pressure roller 30 may be configured not to include the second heat source 33. In the configuration in which the second heat source 33 is not built in the pressure roller 30,
It goes without saying that the third non-contact type temperature sensor 84 becomes unnecessary.

Further, in the above-described embodiment, the first and second temperature sensors 80 and 82 are described as being constituted by non-contact type temperature sensors, but the present invention is limited to such a configuration. However, if one of the temperature sensors is a non-contact type, a desired effect can be obtained. Hereinafter, various modifications of the arrangement of the non-contact type temperature sensor will be described. In the following description, the same parts as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

First, as shown in FIG. 7 as a first modification, the first temperature sensor 80 for detecting the temperature of the fixing roller is constituted by a non-contact type temperature sensor, and the first temperature sensor 80 for detecting the temperature of the heating roller. The second temperature sensor 82 may be constituted by a contact thermistor.

As shown in FIG. 8 as a second modification, the second temperature sensor 82 for detecting the pressure roller temperature is constituted by a non-contact type temperature sensor to detect the fixing roller temperature. The first temperature sensor 80 may be constituted by a contact thermistor.

Further, in the above-described embodiment, the description has been made such that the fixing roller temperature is defined by the temperature of the fixing belt 36 on the fixing roller 28, and the heating roller temperature is defined by the fixing belt on the heating roller 34. However, the present invention is not limited to such a configuration, but directly determines the fixing roller temperature from the surface temperature of the fixing roller 28, May be directly defined from the surface temperature of the pressure roller 34. In this case, as shown in FIG. 9 as a third modification, a first non-contact temperature sensor 80 for detecting the temperature of the fixing roller is disposed at a position facing the outer peripheral surface of the fixing roller 28 at a distance. Non-contact temperature sensor 8 for detecting the temperature of the heating roller
Reference numeral 2 is disposed at a position facing the outer peripheral surface of the pressure roller 34 at a distance.

In FIG. 9, the first and second temperature sensors 80 and 82 are both shown as being constituted by non-contact type temperature sensors, but as described above, It suffices if one of the temperature sensors 80 and 82 is constituted by a non-contact type temperature sensor.

Further, the temperature of the fixing roller is defined based on the temperature of the fixing belt 36 after the fixing roller 28 has deviated from above the fixing roller 28, and the temperature of the heating roller is defined based on the temperature of the fixing belt 36 after the fixing roller 36 has deviated from the heating roller 34. It may be configured as follows.

In this case, as shown as a fourth modified example in FIG. 10, the first non-contact type temperature sensor 80 for detecting the temperature of the fixing roller
Is located downstream with respect to the traveling direction of the fixing roller 36, and is located at a position spaced apart from and facing the portion of the fixing belt 36 located upstream with respect to the traveling direction with respect to the heating roller 34. Is located downstream of the heating roller 34 with respect to the traveling direction of the fixing belt 36 and upstream of the fixing roller 28 with respect to this traveling direction. It will be disposed at a position facing away from the portion 36.

In FIG. 10, the first and second
Each of the temperature sensors 80 and 82 is illustrated as being constituted by a non-contact type temperature sensor, but as described above, one of the temperature sensors 80 and 82 is constituted by a non-contact type temperature sensor. It is good if it is.

[0077]

As described above in detail, according to the present invention, there is provided a fixing device fixing device capable of executing priority control of the heat generating means without damaging the surface of the fixing belt.

[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 front view showing a configuration of a fixing belt.

FIG. 5 is a block front view schematically showing a configuration of a control system.

FIG. 6 is a diagram showing characteristics of each roller temperature when a control method in a control device according to the present invention is applied.

FIG. 7 is a front cross-sectional view illustrating a configuration according to a first modification of the fixing device according to the present invention.

FIG. 8 is a front sectional view showing a configuration according to a second modified example of the fixing device according to the present invention.

FIG. 9 is a front sectional view showing a configuration according to a third modification of the fixing device according to the present invention.

FIG. 10 is a front sectional view showing a configuration according to a fourth modification of the fixing device according to the present invention.

FIG. 11 is a front view schematically showing a configuration of a conventional belt-type fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixing device 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 body 30 Pressure roller 30A Core metal Part 30B Roller main body 32 First heat source (heat generating means) 33 Second heat source (auxiliary heat generating means) 34 Heating roller 36 Fixing belt 36a Belt base 36b Heat resistant elastic release layer 38 Oil application roller 40 First coil spring 42 Second coil spring 44 Guide plate 46 Inlet port 48 Discharge path 50 Lower discharge roller 52 Drive mechanism 54 Upper 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 sensor 80 First non-contact type temperature sensor 82 Second non-contact type temperature sensor 84 Third non-contact type temperature sensor 86 Control device 88 First heater driver 90 Second heater driver 90 Power switch EB Endless belt GE Output gear S Unfixed sheet

Claims (10)

[Claims] A fixing roller, a pressure roller that rolls in contact with the fixing roller at a predetermined pressure, a heating roller that is disposed at a distance from the fixing roller, and that has a heating means disposed therein; A fixing belt that is endlessly wrapped around the roller and the fixing roller, heats unfixed toner on a sheet that receives heat transfer from the heat generating unit and passes through a rolling contact portion of the fixing roller and the pressure roller, First temperature detecting means for detecting the temperature of the fixing roller, second temperature detecting means for detecting the temperature of the heating roller, and the heat generating means based on the detection results of the first and second temperature detecting means. Control means for controlling the heat generation state, wherein the sheet having the unfixed toner carried on its surface passes through the rolling contact portion along one direction, thereby fixing the unfixed toner on the sheet. In the dressing apparatus, at least one of the first and second temperature detecting units includes a non-contact type temperature sensor, and the control unit determines that a detection result of the first temperature detecting unit is lower than a first set temperature. Controlling the amount of heat generated by the heating means so that the temperature of the heating roller becomes a second set temperature, and detecting the detection result of the first temperature detecting means with the first temperature.
The fixing device controls the amount of heat generated by the heat generating means so that when the temperature is equal to or higher than the set temperature, the fixing roller temperature becomes the first set temperature. 2. A fixing device according to claim 1, wherein said first temperature detecting means includes a non-contact type temperature sensor disposed on the outer peripheral surface of said fixing roller so as to be spaced apart and opposed. . 3. The temperature sensor according to claim 1, wherein said first temperature detecting means includes a non-contact type temperature sensor which is disposed in a state of being separated from and facing the fixing belt on said fixing roller.
Fixing device. 4. The fixing belt according to claim 1, wherein the first temperature detecting means is located downstream of the fixing roller in the traveling direction of the fixing belt, and is located upstream of the heating roller in the traveling direction. The fixing device according to claim 1, further comprising a non-contact type temperature sensor disposed so as to face the portion at a distance. 5. A fixing device according to claim 1, wherein said second temperature detecting means includes a non-contact type temperature sensor disposed on the outer peripheral surface of said heating roller so as to be spaced apart and opposed. . 6. The non-contact type temperature sensor according to claim 1, wherein said second temperature detecting means includes a non-contact type temperature sensor disposed so as to face a fixing belt portion on said heating roller. Fixing device. 7. The fixing belt, wherein the second temperature detecting means is located downstream of the heating roller in the running direction of the fixing belt and upstream of the fixing roller in the running direction. The fixing device according to claim 1, further comprising a non-contact type temperature sensor disposed so as to face the portion at a distance. 8. The non-contact type temperature sensor according to claim 1, wherein the non-contact type temperature sensor detects infrared rays emitted from the detected part and detects the surface temperature of the detected part in a non-contact manner. 3. The fixing device according to claim 1. 9. The pressure roller has a built-in auxiliary heating means for heating the pressure roller, and further comprises a third temperature detection means for detecting a surface temperature of the pressure roller. The fixing device according to claim 1. 10. The fixing device according to claim 9, wherein said third temperature detecting means includes a non-contact type temperature sensor.