JP7230384B2 - Belt drive and image forming apparatus - Google Patents

Description

The present invention relates to belt driving devices and image forming apparatuses.

Patent Document 1 describes a pressure roll and a tension roll that suspend a belt and apply a rotational force to the belt, a belt spacing mechanism that abuts and separates the belt and the heating roll, and a lubricant applied to the inner surface of the belt. It is disclosed to have an oil applying member for supplying oil and a belt drive roller for applying a rotational force to the belt by contacting the outer surface side of the belt when the belt is separated from the rotating body.
Further, Japanese Patent Application Laid-Open No. 2002-100000 discloses that an image forming apparatus includes a control unit that operates a tilting unit to perform shift control, which is control of the position of the intermediate transfer belt in the width direction. The control means tilts the steering roller to the first tilted position and then starts shift control. to continue the shift control. Furthermore, when the intermediate transfer belt rotates a certain distance or more while the shift control is being continued, the average tilted position of the steering roller is set as the third tilted position of the steering roller, and the second tilted position is set to the third tilted position at a predetermined timing. Change to tilt position 3.

JP 2009-139437 A JP 2015-138144 A

By the way, in the belt driving device, it is possible to adopt a structure having an inner peripheral rotating member on which the inner peripheral surface of the belt member is engaged and which rotates the belt member, and a position changing member for changing the position of the belt member in the width direction. be. In this configuration, when the stopped belt member is started to rotate, if the position changer is executing the operation of changing the position of the belt member in the width direction, for example, the tension of the belt member is increased in the width direction. Inconsistencies and slippage between the inner rotating body and the belt member may occur.

Therefore, in the present invention, when the rotation of the belt member is started, the slippage that occurs between the inner peripheral rotating body and the belt member is compared with the case where the position changer changes the position of the belt member in the width direction. The purpose is to suppress

The invention according to claim 1 is characterized by a belt member, an inner peripheral rotator on which the inner peripheral surface of the belt member is engaged and which rotates the belt member, and a belt position, which is a position in the width direction of the belt member, at a reference position. A position changer that changes the belt position so as to be movable between a pressing position pressed against the outer peripheral surface of the belt member and a separated position separated from the outer peripheral surface, and the pressing an outer circumference rotator for rotating the belt member at a position, and during normal operation for image formation, controlling the position changer so as to continuously perform an operation with the belt position as the reference position; When the belt member starts to rotate , in a state where the outer peripheral rotating body is arranged at the separated position, in a state in which the movement of the position changer with the belt position as the reference position is restricted, The operation of rotating the belt member by the inner circumference rotator is maintained, and after a predetermined condition is satisfied, the position changer continuously performs the operation of setting the belt position to the reference position. When the belt member starts to rotate and the outer peripheral rotating body is in the pressing position, the movement of the position changing body with the belt position as the reference position is restricted. The belt drive device is characterized in that it does not
The invention according to claim 2 is characterized in that the position changer is rotated by being hooked on the inner peripheral surface of the belt member, and changes the position of the belt by changing the angle of the rotation shaft with respect to the belt member. The belt driving device according to claim 1, wherein:
In the invention according to claim 3, the belt position is the reference position when the belt member starts to rotate, viewed from a direction intersecting the direction in which the angle of the rotation shaft with respect to the belt member is changed. The difference in the angle between the rotation axis of the position changer and the rotation axis of the inner circumference rotor when the movement of the changer is restricted is the rotation of the position changer in the state before the belt member starts rotating. 3. The belt driving device according to claim 2, wherein the difference is smaller than the angle difference between the shaft and the rotation axis of the inner circumference rotor.
According to a fourth aspect of the invention, in a state in which the movement of the position changer is restricted with the belt position as the reference position, the angle of the rotation axis of the position changer is one of predetermined angles. 4. The belt drive device according to claim 3, wherein:
The invention according to claim 5 is characterized in that, before the belt member starts rotating, the rotation axis of the position changer is controlled so as to be along the rotation axis of the inner rotation body. 5. A belt driving device according to item 4.
The invention according to claim 6 is characterized in that the predetermined condition is that a predetermined time has elapsed after the belt member started to rotate by the inner circumference rotating member. 1. A belt drive device according to claim 1.
According to a seventh aspect of the invention, even before the predetermined time elapses, if the deviation of the belt position exceeds a predetermined range, the position changer changes the belt position from the reference position. 7. The belt driving device according to claim 6, wherein the belt driving device is controlled so as to perform the operation of moving the belt.
An eighth aspect of the present invention comprises an image forming unit that forms an image on a recording material, a belt member that rotates as the image forming unit forms an image, and an inner peripheral surface of the belt member that is engaged with the belt member. An inner circumference rotator that rotates the belt member, a position changer that changes the belt position so that the belt position, which is a position in the width direction of the belt member, becomes a reference position, and is pressed against the outer peripheral surface of the belt member. and an outer peripheral rotating body that is movable between a pressing position and a spaced position away from the outer peripheral surface, and rotates the belt member at the pressing position. The position changer is controlled so as to continuously perform the operation of setting the belt position to the reference position, and when the belt member starts rotating , the outer peripheral rotating body is positioned at the spaced position. In some cases, in a state in which the movement of the position changer with the belt position as the reference position is restricted, the movement of rotating the belt member by the inner circumference rotator is maintained to satisfy a predetermined condition. After that, the position changer is controlled so as to continuously perform the operation with the belt position as the reference position , and when the belt member starts rotating, the outer peripheral rotating body is moved to the pressing position. The image forming apparatus is characterized in that, in the arranged state, the movement of the position changer with the belt position as the reference position is not restricted .

According to the invention of claim 1, when the rotation of the belt member is started, the slippage occurring between the inner peripheral rotating body and the belt member can be reduced to the case where the position changer changes the position of the belt member in the width direction. can be suppressed by comparison.
According to the invention of claim 2, in a structure in which variation in tension in the width direction of the belt member is more likely to occur, slippage between the inner peripheral rotating body and the belt member when starting rotation of the belt member is suppressed. be able to.
According to the invention of claim 3, by defining the angle between the rotation axis of the position changer and the rotation axis of the inner rotation body, the rotation of the inner rotation body and the belt member when the rotation of the belt member is started. Slippage between them can be suppressed more reliably.
According to the fourth aspect of the invention, by setting the angle of the rotation axis of the position changer as a specific angle, slippage between the inner circumference rotating body and the belt member when the belt member starts to rotate is prevented. It can be suppressed more reliably.
According to the invention of claim 5, the driving force of the inner peripheral rotating body can be reliably transmitted by the belt member.
According to the sixth aspect of the invention, it becomes easier to control the timing at which the position changer starts adjusting the belt position.
According to the seventh aspect of the invention, it is possible to prevent the belt from becoming excessively displaced before the predetermined time elapses.
According to the invention of claim 8 , when the rotation of the belt member is started, the slippage that occurs between the inner peripheral rotating body and the belt member is reduced when the position changing body changes the position of the belt member in the width direction. can be suppressed compared to

1 is a schematic configuration diagram showing an image forming apparatus to which the exemplary embodiment is applied; FIG. 1 is a schematic configuration diagram showing a fixing device to which the exemplary embodiment is applied; FIG. 1 is a schematic configuration diagram showing a steering mechanism to which this embodiment is applied; FIG. (a) to (c) are diagrams for explaining the operation of the steering roll. 4 is a flowchart for explaining control operations of a control unit; (a) and (b) are diagrams showing the operation of the belt driving device in the standby mode of another embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
<Image forming apparatus 1>
FIG. 1 is a schematic configuration diagram showing an image forming apparatus 1 to which this embodiment is applied. The image forming apparatus 1 shown in FIG. 1 is a so-called tandem color printer. The image forming apparatus 1 controls the image forming section 10 for forming an image corresponding to image data of each color, the sheet supply section 50 for supplying the sheet S to the image forming section 10, and the overall operation of the image forming apparatus 1. and a control unit 100 for controlling.

<Image forming unit 10>
The image forming section 10 includes four image forming units 11Y, 11M, 11C, and 11K arranged in parallel at regular intervals. The image forming units 11Y, 11M, 11C, and 11K form toner images by so-called electrophotography. Here, the image forming units 11Y, 11M, 11C, and 11K are constructed in the same manner except for the toner stored in the developing device 16, which will be described later. The image forming units 11Y, 11M, 11C, and 11K respectively form yellow (Y), magenta (M), cyan (C), and black (K) toner images. For this reason, in the following description, the respective components of the image forming units 11Y, 11M, 11C, and 11K are denoted by symbols "Y", "M", "C", and "K" for distinction. However, these symbols are not attached when there is no need to distinguish them.

The image forming section 10 also includes an intermediate transfer belt 13 onto which toner images of respective colors formed on a photosensitive drum 12 (to be described later) are transferred. The image forming section 10 also includes a primary transfer roll 17 that sequentially transfers (primary transfer) the toner images of the respective colors formed by the image forming units 11 onto the intermediate transfer belt 13 . Further, the image forming unit 10 includes a secondary transfer roll 19 that collectively transfers (secondary transfer) the toner images of the respective colors superimposed on the intermediate transfer belt 13 onto the sheet S, and the secondarily transferred toner images of the respective colors. on the paper S, and a discharge roll 23 for discharging the paper S.

Here, the image forming unit 11 includes a photosensitive drum 12 that holds a toner image, a charging device 14 that charges the photosensitive drum 12, and an electrostatic latent image formed by exposing the surface of the charged photosensitive drum 12. a developing device 16 for developing an electrostatic latent image formed on the photosensitive drum 12 to form a toner image; and a drum cleaning device 18 for removing residual toner on the photosensitive drum 12 .

<Image forming processing>
The image forming apparatus 1 executes a series of image forming processes under the control of the control section 100 . That is, a print job sent from a PC (not shown) or the like is subjected to image processing by an image processing section (not shown) and converted into image data of each color and sent to the exposure device 15 of each image forming unit 11 . A toner image is formed on the photosensitive drum 12 by performing exposure by the exposing device 15 and development by the developing device 16 .

Each color toner image formed on the photosensitive drum 12 of each image forming unit 11 is sequentially primary-transferred onto the intermediate transfer belt 13 by the primary transfer roll 17, and a toner image of each color is superimposed on the intermediate transfer belt 13. form an image. This superimposed toner image is conveyed toward the secondary transfer roll 19 as the intermediate transfer belt 13 moves.

On the other hand, the paper S fed from the paper supply unit 50 is transported toward the secondary transfer roll 19 in synchronization with the transport timing of the superimposed toner image on the intermediate transfer belt 13 . Then, the superimposed toner image on the intermediate transfer belt 13 is secondarily transferred onto the sheet S by the secondary transfer roll 19 . The superimposed toner image transferred to the paper S is fixed on the paper S by the fixing device 60 and then discharged by the discharge roll 23 .

Here, the image forming apparatus 1 has a plurality of power modes (operation modes) with different power consumptions. As the power modes, for example, a normal mode (normal state) for forming an image according to a print job, a standby mode for waiting in preparation for image formation, and a sleep mode (power saving state) for reducing power consumption are set. be. In the standby mode, less power is supplied to the image forming section 10 and the like than in the normal mode. As a result, standby mode consumes less power than normal mode. Further, in the sleep mode, the power supplied to the image forming unit 10 and the like and the power consumption are lower than those in the standby mode.

In the following description, the up-down direction (vertical direction) in the image forming apparatus 1 shown in FIG. 1 may be simply referred to as the "up-down direction". In addition, the upper side in the vertical direction in FIG. 1 may be simply referred to as "upper side", and the lower side in the vertical direction may simply be referred to as "lower side". Further, the horizontal direction of the paper surface of the image forming apparatus 1 shown in FIG. 1 may be simply referred to as the "width direction". In addition, the left side of the paper surface of FIG. 1 may be simply referred to as "one side", and the right side of the paper surface may simply be referred to as "the other side". Further, the depth direction of the paper surface of the image forming apparatus 1 shown in FIG. 1 may be simply referred to as the "depth direction". In addition, the front side of the paper surface of FIG. 1 may be simply referred to as the "front side", and the back side of the paper surface may be simply referred to as the "back side".

<Fixing Device 60>
FIG. 2 is a schematic configuration diagram showing a fixing device 60 to which this embodiment is applied.
Next, a schematic configuration of the fixing device 60 will be described with reference to FIG.

As shown in FIG. 2, the fixing device 60 includes a fixing belt 61, a pressure roll 62, a heating roll 63, a steering roll 64, a fixed pad 65, and a lubricant applicator 66. The fixing device 60 also includes a drive section 67 and a steering mechanism 90 .

The fixing belt 61 is an endless strip, and the inner surface thereof is supported by a heating roll 63 , a steering roll 64 and a fixing pad 65 . The fixing belt 61 circulates along with the rotation of the heating roll 63 and the pressure roll 62 (see arrow D1). The fixing belt 61 has a structure in which a rubber layer and a release layer are provided on a base material. For example, the substrate is made of polyimide and the rubber layer is made of silicone rubber. Also, the release layer is made of fluorine-based resin such as PFA (perfluoroalkoxyalkane).

The heating roll 63 is a cylindrical member made of a metal material. The heating roll 63 is provided with a heater 630 inside and heats the fixing belt 61 from the inner surface of the fixing belt 61 . The outer peripheral surface of the heating roll 63 is configured to have a relatively high coefficient of friction for driving the fixing belt 61 and steering.

The steering roll 64 is a cylindrical member made of metal material. A heater 646 is provided inside the steering roll 64 to heat the fixing belt 61 from the inner surface of the fixing belt 61 . Here, the steering roll 64 is rotatably supported at the central portion of the fixing belt 61 in the width direction (depth direction). As a result, the steering roll 64 can swing around the central portion in the depth direction (see arrows D2 and D3 in the figure). To further explain, the axis of rotation of the steering roll 64 is tiltable.

The fixing pad 65 is pressed against the inner surface of the fixing belt 61 . The fixing pad 65 is made of, for example, a metal material and has a shape elongated in the depth direction. A heater 650 is provided inside the fixing pad 65 to heat the fixing belt 61 from the inner surface of the fixing belt 61 . Of the side surfaces of the fixing pad 65 , the surface facing the pressure roll 62 is a curved surface 65 a that is pressed against the inner surface of the fixing belt 61 . The fixing belt 61 slides on the curved surface 65 a of the fixing pad 65 . The curved surface 65a of the fixed pad 65 is configured to have a relatively low coefficient of friction. Additionally, the fixing pad 65 is a sliding portion on which the fixing belt 61 slides.

The lubricant applicator 66 is arranged inside the fixing belt 61 and applies lubricant to the inner surface of the fixing belt 61 . The lubricant increases the lubricity (reduces the friction coefficient) on the contact surface between the inner surface of the fixing belt 61 and the curved surface 65a of the fixing pad 65, thereby reducing the frictional force. The illustrated lubricant is liquid, for example, amino-modified silicone oil. Lubricant applicator 66 is located between heating roll 63 and fixed pad 65 on the inner surface of fuser belt 61 .

The pressure roll 62 is provided facing the fixed pad 65 with the fixing belt 61 interposed therebetween. The pressure roll 62 has a structure in which the peripheral surface of a cylindrical member made of a metal material is covered with an elastic layer made of a rubber material. The pressure roll 62 can move forward and backward with respect to the fixed pad 65 . Further, the pressure roll 62 presses the outer surface of the fixing belt 61 toward the destination surface 65 a at a position close to the fixing pad 65 . Here, the pressure roll 62 is movable between a pressing position for pressing the fixing belt 61 and a separation position for separating from the fixing belt 61 .

The driving section 67 has a driving motor 671 and a moving mechanism 673 . The drive motor 671 is connected to the pressure roll 62 and the heating roll 63 via a gear train (not shown). The pressure roll 62 and the heating roll 63 are rotated by receiving the drive force from the drive motor 671, which is the same drive source. The moving mechanism 673 is a so-called latch mechanism. The moving mechanism 673 uses a known mechanism such as a cam mechanism (not shown) to advance and retract the pressure roll 62 with respect to the curved surface 65a of the fixed pad 65 (see arrows D4 and D5 in the drawing).

A steering mechanism 90 drives the steering roll 64 . The steering mechanism 90 has a roll drive section 70 and a belt position detection section 80 .
The roll drive unit 70 is provided in connection with the steering roll 64 and supplies driving force for tilting the rotation axis of the steering roll 64 . Specifically, the roll driving section 70 tilts the steering roll 64 in a direction for correcting the deviation according to the position (deviation) of the fixing belt 61 in the width direction (depth direction).

The belt position detector 80 detects the position of the fixing belt 61 in the width direction (depth direction). The roll drive section 70 adjusts the tilt angle of the steering roll 64 according to the position of the fixing belt 61 detected by the belt position detection section 80 .

The drive section 67 , roll drive section 70 and belt position detection section 80 are each controlled by the control section 100 .

Also, a one-way clutch (not shown) may be provided in a gear train (not shown) that drives the pressure roll 62 and the heating roll 63 . This one-way clutch transmits the driving force when it is driven in the direction of forward rotation, and rotates idle without transmitting the driving force when it is driven in the direction of reverse rotation. Slippage of the fixing belt 61 is suppressed even if there is a difference in rotational speed between the fixing belt 61 and the roll 63 .

<Steering Mechanism 90>
FIG. 3 is a schematic configuration diagram showing a steering mechanism 90 to which this embodiment is applied.
Next, the steering mechanism 90 will be described with reference to FIG.
As noted above, steering mechanism 90 drives steering roll 64 . Specifically, in the steering mechanism 90 , the roll drive section 70 controls the steering roll 64 according to the position of the fixing belt 61 detected by the belt position detection section 80 . The steering roll 64 will be described below, and then each of the roll drive section 70 and the belt position detection section 80 included in the steering mechanism 90 will be described.

First, the steering roll 64 will be explained. The steering roll 64 includes a roll main body 640, a roll support 642 that supports the roll main body 640, a drive pin 645 provided on the roll support 642, and a roll rocker serving as a rotation center when the roll support 642 is rocked. and a drive shaft 647 .

The roll body 640 is a metallic cylindrical member. The roll main body 640 is rotatably provided around a roll rotation axis 641 which is the center line of the cylinder. In addition, the fixing belt 61 is wrapped around the outer periphery of the roll body 640 . In the following description, the front side of the roll body 640 may be referred to as the front side end 648, and the back side of the roll body 640 may be referred to as the back side end 649 (see FIG. 4(a-2)).

The roll support 642 is a frame that rotatably supports the front end 648 and the back end 649 of the roll body 640 . The illustrated roll support 642 has a guide disk 643 which is a substantially disk-shaped member and is rotatably provided. The guide disc 643 moves vertically while rotating along the plate surface of the guide plate 601 whose position is fixed, thereby guiding the swinging roll body 640 . Although illustration is omitted, the guide disc 643 is also provided on the depth side.

The drive pin 645 is a substantially cylindrical member provided on the front side of the roll support 642 in the depth direction. In the illustrated example, the drive pin 645 is provided along the roll rotation axis 641 of the roll body 640 . Although the details will be described later, the drive pin 645 is pushed by the drive lever 75 and moves vertically (see arrows D2 and D3 in the drawing).

The roll rocking shaft 647 is provided at the longitudinal central portion of the roll support 642 , in other words, at the longitudinal central portion of the roll rotation shaft 641 , and supports the roll support 642 rotatably. Here, when the roll support 642 rotates around the roll swing shaft 647, the roll main body 640 supported by the roll support 642 swings. To explain further, when the roll body 640 swings, the front end 648 and the rear end 649 of the roll body 640 move vertically.

Next, the roll driving section 70 will be described. The roll drive unit 70 is provided on the front side of the steering roll 64 and supplies a driving force for rocking the steering roll 64 . The roll drive unit 70 in the illustrated example includes a steering drive motor 71 serving as a drive source, a first gear 72 and a second gear 73 for transmitting the drive force from the steering drive motor 71, and a drive force from the second gear 73. It has a drive lever 75 that receives and rotates, a drive lever spring 77 that biases the drive lever 75 , and a steering angle sensor 79 that detects the amount of movement of the drive lever 75 .

Here, the drive lever 75 is a plate-like member having a generally sectoral shape in a plan view. Gear teeth (not shown) that mesh with the second gear 73 are formed on the outer circumference of the substantially fan-shaped chord portion 750 of the drive lever 75 . A lever cylindrical portion 751 is formed in the substantially fan-shaped central portion of the drive lever 75 . The lever cylindrical portion 751 is rotatably supported by a rotating shaft (not shown) extending in the depth direction (see arrows D4 and D5 in the drawing). The driving lever 75 also has a pressing surface 753 which is a radial side surface of the fan shape and presses the driving pin 645 , and a shielding portion 755 which protrudes forward from the plate surface of the driving lever 75 in the depth direction.

Also, the steering angle sensor 79 in the illustrated example is a transmissive photosensor that detects the presence or absence of an object between the light emitting element and the light receiving element arranged facing each other. The steering angle sensor 79 is provided in the movement area of the shielding portion 755 that reciprocates with the rotation of the drive lever 75 and detects passage of the shielding portion 755 .

Here, the drive pin 645 of the drive lever 75 is provided above the pressing surface 753 of the drive lever 75 in the vertical direction and is biased downward by the drive lever spring 77 . This keeps the drive pin 645 pressed against the pressing surface 753 of the drive lever 75 . Then, when the steering drive motor 71 is driven and the drive lever 75 rotates around the lever cylindrical portion 751 (see arrows D4 and D5 in the figure), the drive pin 645 is pressed by the pressing surface 753 of the drive lever 75, and vertically moves. direction (see arrows D2 and D3 in the figure).

Next, the belt position detection section 80 will be described. The belt position detection unit 80 has an actuator 81 pressed by the fixing belt 61, a belt position detection sensor 83 for detecting the position of the fixing belt 61, and a support structure 85 for supporting the actuator 81 and the belt position detection sensor 83. .

The actuator 81 has an actuator main body 811 that is an elongated member, a cylindrical portion 813 that is formed in the longitudinal central portion of the actuator main body 811, and a first end 815 and a second end that are both longitudinal ends of the actuator main body 811. 817 , a shielding portion 819 that is a protrusion provided on the second end 817 , and an actuator spring 821 that biases the actuator body 811 .

Here, the actuator main body 811 is provided with the first end 815 pressed against the side surface of the fixing belt 61 . Further, the actuator spring 821 biases the actuator body 811 so that the first end 815 rotates toward the fixing belt 61 (from the near side to the far side in the depth direction). Accordingly, the state in which the first end 815 of the actuator body 811 is pressed against the side surface of the fixing belt 61 is maintained. Then, when the fixing belt 61 moves in the depth direction, the first end 815 moves in the depth direction. As the first end 815 moves, the actuator body 811 rotates around the cylindrical portion 813 (see arrows D6 and D7 in the drawing). That is, the attitude of the actuator 81 changes along with the widthwise position of the fixing belt 61 . Note that when the actuator body 811 rotates about the cylindrical portion 813, the second end 817 rotates.

The belt position detection sensor 83 has a first sensor 831 , a second sensor 832 and a third sensor 833 that detect the position of the second end 817 of the actuator body 811 . The first sensor 831 to third sensor 833 are transmissive photosensors. The first to third sensors 831 to 833 are provided along the direction of movement of the shielding portion 819 that reciprocates as the actuator 81 rotates, and detect passage of the shielding portion 755 . In addition, the first sensor 831 detects that the fixing belt 61 moving in the width direction by belt walk control is positioned at the frontmost side (see the front side position P1 in the drawing). Further, the third sensor 833 detects that the fixing belt 61 moving in the width direction by belt walk control is positioned at the farthest side (see the far side position P2 in the drawing). Further, the second sensor 832 detects that the fixing belt 61 is arranged outside the area in which the fixing belt 61 is arranged in belt walk control, that is, between the front side position P1 and the back side position P2.

The support structure 85 has a support plate 851 that supports the first to third sensors 831 to 833 and a rotation shaft 853 around which the actuator 81 rotates.

The operation of the drive mechanism for the steering roll 64 configured as described above will be described.
First, the posture of the actuator 81 is detected by detecting the shielding portion 819 of the actuator 81 with the first sensor 831 to the third sensor 833 of the belt position detection sensor 83 . The attitude of the actuator 81 changes according to the widthwise position of the fixing belt 61 as described above. Therefore, the width direction position of the fixing belt 61 is detected by the belt position detection sensor 83 detecting the shielding portion 819 . Then, the steering drive motor 71 is driven in accordance with the detected position of the fixing belt 61 in the width direction. The driving force of the steering drive motor 71 causes the drive lever 75 to rotate (see arrows D4 and D5 in the figure), thereby moving the drive pin 645 vertically (see arrows D2 and D3 in the figure). The roll body 640 swings.

<Operation of Steering Roll 64>
4A to 4C are diagrams for explaining the operation of the steering roll 64. FIG. 4(a-2), (b-2), and (c-2) are from a direction orthogonal (intersecting) the direction in which the angle of the roll rotation shaft 641 of the steering roll 64 with respect to the fixing belt 61 is changed. It is a view.
Next, the operation of the steering roll 64 will be described with reference to FIGS. 3 and 4(a) to (c).

First, the steering roll 64 swings by being driven by the steering mechanism 90 as described above. When the steering roll 64 swings, the tilt angle (turning angle, see angle α in FIG. 4(a-2)), which is the angle between the roll rotation axis 641 of the steering roll 64 and the reference line HL, changes. Note that the reference line HL shown in FIG. 4 is a virtual line along the horizontal direction. To explain further, the reference line HL may be regarded as the rotation axis of the heating roll 63 that is the driving roll of the fixing belt 61 .

With such a change in the tilt angle, as shown in FIG. , the front side end 648 of the steering roll 64 is positioned above the back side end 649, and the posture is switched.

Moreover, the steering roll 64 has a posture in which the front end 648 of the steering roll 64 is positioned on the lower side shown in FIG. When switching the posture, the front side end 648 of the steering roll 64 is vertically aligned with the far side end 649, that is, the roll rotation shaft 641 becomes a posture along the internal driving roll (see FIG. 4C). . Here, if the position of the steering roll 64 shown in FIG. 4A is the first position and the position of the steering roll 64 shown in FIG. 4B is the second position, the steering roll 64 shown in FIG. is an intermediate position (neutral position) between the first position and the second position. The turning angle (neutral turning angle) of the steering roll 64 arranged at the neutral position is zero degrees.

The meandering of the fixing belt 61 can be controlled by the steering mechanism 90 . Specifically, the belt position detection sensor 83 detects the positional variation of the fixing belt 61 in the width direction (depth direction), and based on the detection result, the steering drive motor 71 is driven to change the inclination of the steering roll 64 . . As a result, the widthwise position of the fixing belt 61 is controlled.

In the illustrated example, while the fixing belt 61 is rotating, the steering mechanism 90 basically intermittently changes the inclination of the steering roll 64 to continuously change the position of the fixing belt 61 in the width direction (belt walk). cause). For example, when the belt position detection sensor 83 detects that the fixing belt 61 is at one of the front side position P1 and the back side position P2, the steering roll is adjusted so that the fixing belt 61 moves toward the other position. Repeat switching the posture of 64 between a first position (see FIG. 4(a)) and a second position (see FIG. 4(b)).

By continuously changing the position of the fixing belt 61 in the width direction in this manner, a thrust force is generated along the roll rotation shaft 641 and the position of the fixing belt 61 can be easily controlled. In addition, for example, when there is a so-called burr at the edge of the sheet S passing through the fixing belt 61 , concentrated damage to a specific portion of the fixing belt 61 is suppressed.

<Slip of Fixing Belt 61>
As described with reference to FIG. 2, the fixing belt 61 circulates as the heating roll 63 rotates. Lubricant is applied to the inner surface of the fixing belt 61 by the lubricant applicator 66 . Further, the fixing belt 61 slides on the curved surface 65 a of the fixing pad 65 .

In this way, in the mechanism in which the lubricant exists on the inner surface of the fixing belt 61 and the sliding portion is formed, when the heating roll 63 provided on the inner surface of the fixing belt 61 is driven, friction due to the lubricant occurs. The heating roll 63, which is the drive roll, and the fixing belt 61 may slip due to the reduction in force or the resistance of the sliding portion. If the fixing belt 61 slips, the temperature distribution in the heating roll 63 deteriorates, leading to deterioration in image quality (eg, image defects) and damage to members due to localized heating (eg, damage to the fixing belt 61).

Here, if the fixing device 60 is provided with the steering mechanism 90, the fixing belt 61 is more likely to slip. To explain further, the steering roll 64 is tilted for belt walk control when the fixing belt 61 is driven as described above. Uneven directional tension. If the tension in the axial direction becomes uneven in this way, the torque transmission efficiency from the heating roll 63 to the fixing belt 61 may be lowered. In addition, if the heating roll 63 and the steering roll 64 are adjacent to each other in the circulating direction of the fixing belt 61, as in the illustrated fixing device 60, the tension distribution in the axial direction of the fixing belt 61 becomes uneven, resulting in torque transmission. Efficiency tends to be lower.

As a configuration for suppressing such slippage of the fixing belt 61, there is a mode in which a member for assisting the driving of the fixing belt 61 is provided from the outer surface of the fixing belt 61 to which lubricant is not applied, for example, but this increases the number of parts. and increase the cost and machine size.

In the present embodiment, steering mechanism 90 switches control between normal operation, that is, image formation, and start of rotation of fixing belt 61 . During normal operation, the belt walk control is continuously performed as described above. Specifically, the states shown in FIGS. 4A and 4B are repeated. On the other hand, when the rotation of the fixing belt 61 is started, that is, when the stationary fixing belt 61 is rotated by the heating roll 63 which is a drive roll, the state shown in FIG. maintain. Along with this, the slippage of the fixing belt 61 that occurs when the fixing belt 61 starts to rotate is reduced.

<Control at Start of Rotation of Fixing Belt 61>
Below, the control at the start of rotation of the fixing belt 61 will be described.
First, the steering mechanism 90 brings the steering roll 64 to the neutral position before the fixing belt 61 starts rotating, that is, before the heating roll 63 starts rotating. With the steering roll 64 at the neutral position, the heating roll 63 starts to rotate. Then, after a predetermined time (standby time) has passed, the control is switched to normal operation. That is, the belt walk control is continuously performed.

Here, in the control at the start of rotation of the fixing belt 61, the roll driving section 70 places the steering roll 64 at the neutral position. That is, regardless of the output of the belt position detection section 80, the roll driving section 70 places the steering roll 64 at the neutral position. On the other hand, in the control of the fixing belt 61 during normal operation, the control of the steering roll 64 is executed according to the output of the belt position detection section 80 . In addition, in the control at the start of rotation of the fixing belt 61, the operation of the roll driving section 70 is restricted with the position of the fixing belt 61 set to a reference position such as the front side position P1. In addition, in the control at the start of rotation of the fixing belt 61, the duration of the steering roll 64 at the neutral position is longer than during normal operation.

<Control operation of control unit 100>
FIG. 5 is a flow chart for explaining the control operation of the control unit 100. As shown in FIG.
Next, the control operation of the control unit 100 will be described with reference to FIG. Here, as an initial state, the fixing device 60 is not in operation, and the control when the fixing belt 61 starts to rotate as the pressure roll 62 rotates will be described.

First, the control unit 100 determines whether the pressure roll 62 is placed at the separated position (step 601). Then, when the pressure roll 62 is arranged at the separated position (YES in step 601), the cutting angle is changed to the neutral cutting angle (step 602).

Next, the controller 100 drives the drive motor 671 to rotate the heating roll 63 (step 603). As the heating roll 63 rotates, the fixing belt 61 rotates. Since the heating roll 63 and the pressure roll 62 are connected to the drive motor 671 which is the same drive source, the pressure roll 62 rotates as the drive motor 671 is driven. However, since the pressure roll 62 is arranged at the separated position, it does not supply the driving force to the fixing belt 61 .

Next, the control unit 100 determines whether the waiting time has passed (step 604). If the standby time has elapsed (YES at step 604), the steering mechanism 90 starts belt walk control (step 605).

Further, when the pressure roll 62 is not arranged at the separated position, that is, when the pressure roll 62 is arranged at the pressing position (NO in step 601), the driving motor 671 is driven to Roll 62 is rotated (step 606). Along with this, the fixing belt 61 to which driving force is supplied from the heating roll 63 and the pressure roll 62 starts rotating.

<Other embodiments>
6(a) and (b) are diagrams showing the operation of the belt drive devices 600, 700 in the standby mode of another embodiment.
Next, operations of the belt driving devices 600 and 700 in other embodiments will be described with reference to FIGS. 6(a) and 6(b). In addition, in the following description, the same reference numerals may be assigned to the same configurations as in the above-described embodiment, and the description thereof may be omitted.

First, it was explained that the fixing device 60 described with reference to FIG. It is not limited to this. For example, a configuration without at least one of the fixed pad 65 and the lubricant applicator 66 may be used.

Further, in the above description, it has been described that the pressure roller 62 and the heating roller 63 are rotated by the drive motor 671, which is the same drive source, but the present invention is not limited to this. For example, the pressure roll 62 and the heating roll 63 may be driven by separate drive sources.

In the above description, the control of the fixing belt 61 in the fixing device 60 has been described. The above configuration may be employed for a device that drives belt members other than the fixing belt 61, such as an intermediate transfer belt and a cooling belt.

Specifically, it may be configured as a belt driving device 600 shown in FIG. 6A, for example. The belt driving device 600 has a belt member 610 that is an example of a tension belt, a pressing roll 660 , a steering roll 680 and a pressure roll 620 . Belt member 610 is supported from the inner side by pressing roll 660 and steering roll 680 . Also, the pressing roll 660 and the pressure roll 620 are driven by separate drive sources (not shown). Further, the pressure roll 620 is provided on the opposite side of the pressing roll 660 with the belt member 610 interposed therebetween, and is arranged at either the separated position or the pressing position. In such a belt driving device 600 , by arranging the steering roll 680 at the neutral position when the belt member 610 starts rotating, slippage between the pressing roll 660 and the belt member 610 is reduced.

Alternatively, for example, a configuration such as a belt driving device 700 shown in FIG. 6B may be used. The belt driving device 700 has a belt member 710 , a driving roll 730 , a steering roll 740 , a pressing roll 760 and a pressure roll 720 . The belt member 710 is supported from its inner surface by a drive roll 730 , a steering roll 740 and a pressing roll 760 . In addition, drive roll 730 and pressure roll 720 are driven by separate drive sources (not shown). Further, the pressure roll 720 is provided on the opposite side of the pressing roll 760 with the belt member 710 interposed therebetween, and is arranged at either the separated position or the pressing position. In such a belt drive device 700 , by arranging the steering roll 740 at the neutral position when the belt member 710 starts rotating, slippage between the drive roll 730 and the belt member 710 is reduced.

<Others>
For example, when the image forming apparatus 1 is in a standby mode in which the image forming apparatus 1 waits for image formation, the drive motor 671 may be intermittently switched on and off in order to uniform the temperature distribution of the fixing belt 61 . . In such a configuration, the driving motor 671 is turned on after the steering roll 64 is placed in the neutral position each time the driving motor 671 is switched from off to on, thereby suppressing the slipping of the fixing belt 61 . good too.

Further, in the above embodiment and the like, it was explained that a predetermined time has elapsed as a trigger for switching from the start of rotation of the fixing belt 61 to the control of the normal operation. As long as the slippage of the fixing belt 61 is suppressed, the switching condition is not particularly limited.

For example, it may be triggered by the speed (for example, peripheral speed) of the fixing belt 61 exceeding a predetermined reference. To explain further, a speed detection sensor (not shown) for detecting the speed of the fixing belt 61 may be provided, and the output value of the speed detection sensor may be within a predetermined range for a predetermined time. A torque detection circuit (not shown) is provided to detect the torque of the drive motor 671 that drives the heating roll 63. When the output value of this torque detection sensor falls within a predetermined range for a predetermined time, good too.

It should be noted that after the rotation of the fixing belt 61 is started and before a predetermined condition is satisfied, the control for switching to the control for normal operation may be performed. For example, even if the speed of the fixing belt 61 is out of the predetermined range for a predetermined time, if the fixing belt 61 deviates in the width direction beyond the predetermined range, forcibly , the turning angle of the steering roll 64 may be changed from the neutral turning angle to an angle suitable for belt walk. As a result, damage to the fixing belt 61 and the like caused by the fixing belt 61 shifting in the width direction is suppressed. To explain further, excessive meandering of the fixing belt 61 during the rotating operation of the fixing belt 61 is suppressed. When the control is forcibly switched to normal operation before a predetermined condition is satisfied, the turning angle may be smaller than when the speed of the fixing belt 61 is stable during normal operation. Such a small turning angle suppresses the fixing belt 61 from slipping while suppressing damage to the fixing belt 61 .

Further, in the above description, it has been described that the drive motor 671 is turned on after the steering roll 64 is placed at the neutral position. Here, the drive motor 671 may be turned on before the steering roll 64 is completely placed in the neutral position after the movement of the steering roll 64 toward the neutral position is completed. Alternatively, the drive motor 671 may be turned on while starting to move the steering roll 64 toward the neutral position. In the above description, the neutral position is the angle at which the turning angle of the steering roll 64 is zero degrees. As long as it is an intermediate position between the two positions, the turning angle of the steering roll 64 may be other than zero degrees. Alternatively, a plurality of neutral positions may be set, and control may be performed using one of the plurality of neutral positions according to, for example, the position of the fixing belt 61 in the width direction.

Further, when the steering roll 64 is already placed at the neutral position, the steering roll 64 does not have to be moved. To explain further, for example, when stopping the rotation of the fixing belt 61, the steering roll 64 may be controlled to be placed at the neutral position. In this case, when the rotation of the fixing belt 61 is started, the steering roll 64 is already placed at the neutral position, so the drive motor 671 can be turned on without moving the steering roll 64 . The control at the start of rotation of is simplified.

Further, although it has been described that the position of the fixing belt 61 in the width direction is adjusted by the steering roll 64, the present invention is not limited to this. For example, the position of the fixing belt 61 in the width direction may be adjusted by pressing the side surface of the fixing belt 61 , or a rotating roll (not shown) that rotates while hanging the inner surface of the fixing belt 61 may be attached to the fixing belt 61 . The widthwise position of the fixing belt 61 may be adjusted by moving it in the widthwise direction.

Note that the fixing belt 61 in the above description is an example of a belt member. The heating roll 63 is an example of an inner rotating body. Steering roll 64 is an example of a position changer. A neutral cutting angle is an example of a predetermined angle. The controller 100 is an example of a rotation starter. The pressure roll 62 is an example of an outer circumference rotating body. The pressed position is an example of a pressed position.

Although various embodiments and modifications have been described above, it is of course possible to combine these embodiments and modifications.
In addition, the present disclosure is not limited to the above embodiments, and can be embodied in various forms without departing from the gist of the present disclosure.

DESCRIPTION OF SYMBOLS 1... Image forming apparatus 10... Image forming part 60... Fixing device 61... Fixing belt 62... Pressurizing roll 63... Heating roll 64... Steering roll 90... Steering mechanism

Claims (8)

a belt member;
an inner peripheral rotating body on which the inner peripheral surface of the belt member is engaged and which rotates the belt member;
a position changer for changing the belt position so that the belt position, which is the position in the width direction of the belt member, becomes a reference position;
an outer rotating body that is movable between a pressing position pressed against the outer peripheral surface of the belt member and a spaced position away from the outer peripheral surface, and that rotates the belt member at the pressing position;
with
during normal operation for image formation, controlling the position changer so as to continuously perform the operation with the belt position as the reference position;
When the belt member starts to rotate , in a state where the outer peripheral rotating body is arranged at the separated position, in a state in which the movement of the position changer with the belt position as the reference position is restricted, The operation of rotating the belt member by the inner circumference rotator is maintained, and after a predetermined condition is satisfied, the position changer continuously performs the operation of setting the belt position to the reference position. control and
When the belt member starts rotating, if the outer peripheral rotating body is in the pressing position, the movement of the position changer with the belt position as the reference position is not restricted.
A belt drive, characterized by: 2. The belt drive according to claim 1, wherein the position changer is rotated by being hooked on the inner peripheral surface of the belt member, and changes the position of the belt by changing the angle of the rotation shaft with respect to the belt member. Device. When viewed from the direction intersecting the direction of changing the angle of the rotation shaft with respect to the belt member, the belt position when the belt member starts rotating is used as the reference position, and the movement of the position changer is restricted. The difference in the angle between the rotation axis of the position changer and the rotation axis of the inner rotation body is the rotation of the rotation axis of the position changer and the inner rotation body in the state before the belt member starts rotating. 3. The belt drive device according to claim 2, wherein the difference is smaller than the angle difference with the shaft. 4. An angle of the rotation axis of the position changer is one of predetermined angles in a state where the movement of the position changer is restricted with the belt position as the reference position. Belt drive as described. 5. The belt driving device according to claim 4, wherein the rotation axis of the position changer is controlled so as to be aligned with the rotation axis of the inner circumference rotator before the belt member starts rotating. 2. The belt driving device according to claim 1, wherein the predetermined condition is that a predetermined time has elapsed after the belt member has started to rotate by the inner circumference rotator. If the deviation of the belt position exceeds a predetermined range even before the predetermined time elapses, the position changer is controlled to perform the operation of setting the belt position to the reference position. 7. The belt driving device according to claim 6, wherein: an image forming unit that forms an image on a recording material;
a belt member that rotates as the image forming unit forms an image;
an inner peripheral rotating body on which the inner peripheral surface of the belt member is engaged and which rotates the belt member;
a position changer for changing the belt position so that the belt position, which is the position in the width direction of the belt member, becomes a reference position;
an outer rotating body that is movable between a pressing position pressed against the outer peripheral surface of the belt member and a spaced position away from the outer peripheral surface, and that rotates the belt member at the pressing position;
with
during normal operation for image formation, controlling the position changer so as to continuously perform the operation with the belt position as the reference position;
When the belt member starts to rotate , in a state where the outer peripheral rotating body is arranged at the separated position, in a state in which the movement of the position changer with the belt position as the reference position is restricted, The operation of rotating the belt member by the inner circumference rotator is maintained, and after a predetermined condition is satisfied, the position changer continuously performs the operation of setting the belt position to the reference position. control and
When the belt member starts rotating, if the outer peripheral rotating body is in the pressing position, the operation of the position changer with the belt position as the reference position is not restricted. An image forming apparatus characterized by:

Images