JPH1048992A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which can prevent the generation of a skewing and a jitter of a recording paper. SOLUTION: This device is composed to rotate a driving gear engaged to a coupled driving gear provided to 8 press roller 50, so as to give an initial rotating speed to the press roller 50 in a specific direction, when the press roller 50 is moved to its operating position, and to hold a recording paper between the press roller 50 and a heat roller 40 while rotating the press roller 50. Consequently, the generation of a skewing and a jitter of the recording paper which are generated by contacting the recording paper to the stopping press roller 50 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing an image such as a toner image on recording paper in a printer or the like which forms an image by an electrophotographic method.

[0002]

2. Description of the Related Art A fixing device for fixing a toner image transferred to a recording sheet is provided in a printer or the like which forms an image by using an electrophotographic method. The fixing device fixes the toner image on the recording paper by pressing and heating the recording paper between a heat roller having a built-in heat source and a press roller having a surface made of an elastic material.

Generally, in a fixing device, a heat roller is driven to rotate, and a press roller rotates following the heat roller. The heat roller and the press roller are opened and closed by moving the press roller between an operation position where the recording paper is sandwiched between the heat roller and a retracted position separated from the heat roller. Further, if the recording paper is in contact with the heat roller in a stopped state, the recording paper abnormally dries, so that the press roller closes after the conveyance of the recording paper starts and sandwiches the recording paper.

[0004]

However, since the press roller is stopped at the retracted position, at the moment when the recording paper is sandwiched between the heat roller and the heat roller, the conveyed recording paper and the stopped press roller are stopped. Will come into contact with. Therefore, if there is a delicate difference in the timing of sandwiching the recording paper at both ends in the width direction, the brake is temporarily applied to the one sandwiched first, and the recording paper is skewed. is there.

Further, when the transfer of the toner image to the recording paper is performed at the transfer portion located upstream of the fixing device in the transport direction, the transportation of the recording paper is stopped for a moment or the speed is reduced. The so-called jitter may occur in which the position of the toner image transferred to the recording paper fluctuates in the transport direction.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device capable of preventing skewing of recording paper and occurrence of jitter.

[0007]

In order to solve the above-mentioned problems, a fixing device according to the present invention comprises a heat roller having a built-in heat source, an operation position for pressing recording paper between the heat roller, A press roller movable between a retracted position retracted from a position, a rotating means for rotating a heat roller, and an open / close mechanism for moving the press roller between an operating position and a retracted position to open and close the two rollers Means for moving the press roller to the operating position after the heat roller starts rotating, and rotating the press roller in a predetermined direction when the press roller moves to the operating position by the opening and closing means. The apparatus further includes a rotation initial speed providing means for providing an initial speed.

As described above, when the press roller is moved to the operation position, by applying the initial rotation speed to the press roller, the press roller can be brought into contact with the recording paper in a rotated state. Accordingly, it is possible to prevent the recording paper from being skewed or jittered, which is generated when the stopped press roller comes into contact with the recording paper being conveyed.

[0009] The rotation initial speed applying means may be a drive gear that engages with a driven gear provided on the press roller when the press roller is located at the retracted position or between the retracted position and the operating position. it can. As described above, by utilizing the temporary engagement between the driving gear and the driven gear, it is possible to provide the press roller with the initial rotation speed with a simple configuration.

Further, the driving gear may be configured to be driven by rotating means. With this configuration, it is possible to give a sufficient initial rotation speed before the press roller moves to the operation position. Alternatively, the drive gear may be configured to stop rotation in a predetermined direction.
According to this configuration, the initial rotation speed can be given to the press roller using the driving force when the press roller moves to the operation position, so that the configuration is further simplified.

The above-mentioned rotation initial speed applying means may be a contact roller which comes into contact with the surface of the press roller when the press roller is at the retracted position or between the retracted position and the operating position. With such a configuration, it is not necessary to provide a gear or the like on the press roller, so that it is possible to simplify the press roller and a configuration for holding the press roller.

Further, the contact roller may be configured to be driven by a rotating means. With this configuration, it is possible to give a sufficient initial rotation speed before the press roller moves to the operation position. Alternatively, the contact roller may be configured to stop rotation in a predetermined direction. According to this structure, the initial rotation speed can be given to the press roller by using the driving force at the time of moving to the operation position of the press roller, so that the structure is further simplified.

When the press roller is at the retracted position, the rotation speed applying means contacts the press roller surface,
It is also possible to use a slide arm that moves in the tangential direction of the press roller at the contact position. The slide arm is for moving another member, for example, a corona charger in the transfer section of the printer, between the operation position and the retreat position in conjunction with the opening / closing means.

Further, the above-mentioned initial rotation speed applying means is provided on the press roller for blowing air toward the press roller and for rotating the press roller in a predetermined direction by receiving the air from the fan. It can be an impeller. With this configuration, it is possible not only to prevent skew and jitter of the recording paper, but also to uniformly cool the entire press roller.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a fixing device according to the present invention will be described. A printer 1 according to an embodiment is a printer that forms an image on a continuous recording sheet by using a so-called electrophotographic method.

First, a schematic configuration of the printer 1 will be described. FIG. 1 is a side view showing a schematic configuration of the printer 1. 1, a printer 1 includes a scanning optical device 15 that irradiates a laser beam modulated in accordance with image information, a photosensitive drum 16 that forms a latent image by light emitted from the scanning optical device 15, a photosensitive drum 16, A charging unit 17 for uniformly charging the toner image 16, a developing unit 18 for developing the latent image with toner, a transfer unit 20 for transferring the toner image to recording paper, and a fixing device 30 for fixing the toner image to recording paper. It is housed in the housing 10.

The recording paper is inserted through an insertion opening 11 formed on the right side of the housing 10 in the drawing,
The toner passes through the fixing device 30 and is discharged from a discharge port 12 provided on the left side of the housing 10 in the drawing. The recording paper is transported by a tractor unit 60 provided between the transfer unit 20 and the fixing device 30. The tractor unit 60 is configured to move around a tractor belt 61 having projections engaging with feed holes provided at both ends in the width direction of the recording paper by a pair of pulleys 62, and the pulley 62 is driven by a tractor motor 84. Is done.

The image formation is performed as follows. The laser light modulated according to the image information is applied to the scanning optical device 1
5, and the surface of the photosensitive drum 16 is exposed. The photosensitive drum 16 on the surface of the photosensitive drum 16 is uniformly charged by the charging unit 17 and exposed to the modulated laser light to form a latent image. The developing unit 18 applies toner to the latent image formed on the surface of the photosensitive drum 16 to form a toner image. The toner image on the surface of the photosensitive drum 16 is transferred to the recording paper by discharging the corona charger 19 in the transfer unit 20, and the toner image transferred to the recording paper is pressed and heated by the fixing device 30 to be fixed on the recording paper. Is done. The residual toner remaining on the surface of the photoconductor drum 16 is removed by the cleaning unit 13, and the surface of the photoconductor drum is neutralized by the neutralization unit 14 to prepare for the next image formation.

A control unit 80 controls a tractor motor 84 for driving the tractor unit 60, a fixing drive motor 82 for driving the fixing device 30, which will be described later, and a main motor 86 for rotating the photosensitive drum 16 and the like. Is done.

The upper portion of the housing 10 is an upper housing 10a which can be swingably opened, and a scanning optical device 15 is housed in the upper housing 10a. Therefore, the user can swing open the upper housing 10 a and face the fixing device 30 or the tractor unit 60 from above the printer 1.

The fixing device 30 includes a heat roller 40 having a built-in heat source and a press roller 5 having a surface made of an elastic material.
0 is provided. Further, the fixing device 30 is provided with an opening and closing mechanism 33 for opening and closing the heat roller 40 and the press roller 50. The opening / closing mechanism 33 moves the press roller 50 between an operation position for pressing the recording paper with the heat roller 40 and a retracted position retracted from the operation position.

Here, in the transfer section 20, the corona charger 19 is supported by a swing holder 22 that is swingably provided by a swing shaft 21, and an action position close to the surface of the photosensitive drum 16, It is possible to move between the evacuated position and the separated position. The swing holder 22 swings by a slide arm 23 that slides in the left and right direction in the figure in conjunction with the opening and closing mechanism 33.

A discharge roller section 70 for discharging the recording paper is provided between the fixing device 30 and the discharge port 12. The discharge roller unit 70 includes an upper roller 71 and a lower roller 72 disposed above and below the recording paper. The upper roller 71 moves in conjunction with the opening and closing mechanism 33 between an operation position where the recording paper is sandwiched between the lower roller 72 and a retracted position retracted from the operation position. In the present specification, illustration and description of a configuration for moving the upper roller 71 of the discharge roller unit 70 between the operation position and the retreat position is omitted.

The printer 1 allows the user to separate or visually check the page on which the image has been formed.
When the image forming process is completed, the page of the recording paper on which the image has been formed is temporarily discharged out of the printer 1.
Then, when performing the next image formation, the recording paper is pulled back and the image formation is restarted. Therefore, when the recording paper is pulled back or stopped, the opening and closing mechanism 33 moves the press roller 50, the corona charger 19, and the upper roller 71 to the standby position to open the recording paper conveyance path.

Next, details of the fixing device 30 will be described. FIG. 2 is a perspective view showing the heat roller 40, the press roller 50, and a frame holding both rollers. As shown in FIG. 2, the heat roller 40 and the press roller 50
Are supported in parallel by an upper frame 120 and a lower frame 130 which are vertically stacked. The upper frame 120 has a substantially rectangular parallelepiped shape with an open lower surface. The lower frame 130 includes a substantially rectangular bottom plate 131 and side plates 132 erected at both longitudinal ends of the bottom plate 131.

The lower frame 130 has a press roller 5
A U-shaped groove 133 is formed at the upper end 132a and extends downward so as to insert the zero support shaft 51 therethrough.
The groove 133 has a width along which the support shaft 51 can move.

On both sides in the longitudinal direction of the upper frame 120, an inverted U-shaped groove 12 opening at the lower end and extending upward.
3 are formed. The width of the groove 123 is the heat roller 40
The bearing 43 is formed larger than the outer diameter of the bearing 43 by a predetermined amount. Also, the upper end 13 of the side plate 132 of the lower frame 130
2a has a curved shape along the outer periphery of the bearing 43. Therefore, the bearing 43 is provided in the groove 12 of the upper frame 120.
3 and the upper end 132a of the side plate 132 of the lower frame 130
And held by.

FIG. 3 is a view showing the heat roller, the press roller, and the upper and lower frames with a part thereof being cut away. The heat roller 40 has a heat source 41 provided inside a hollow roller portion 40a. The roller section 40a
At both ends in the longitudinal direction, support shafts 42 are formed so as to protrude, and both support shafts 42 are held by bearings 43 which are radial bearings. Further, the heat roller 4
A roller gear 44 for rotating the lens 0 is fixed. Note that a description and illustration of a configuration for heating the heat source of the heat roller 40 is omitted.

The press roller 50 is a driven roller that rotates following the heat roller 40 in a state where the recording paper is pressed against the heat roller 40. Press roller 50
Is a roller section 50 whose surface is made of an elastic member such as rubber.
a, and a support shaft 51 protruding from both ends in the axial direction of the roller portion 50a.

When the heating of the heat source 41 of the heat roller 40 is started, the roller portion 40a, the support shaft 42, the bearing 43, and the upper and lower frames 120 and 130 are heated in this order. Therefore, a predetermined amount of clearance is provided between the support shaft 42 and the bearing 43 and between the bearing 43 and the upper frame 120, respectively.

FIG. 4 is a view of the fixing device 30 as viewed from the downstream side in the transport direction. The fixing device 30 is mounted on a base frame 35 having a U-shaped cross section. The base frame 35 includes a rectangular bottom plate 36 and a pair of side plates 37 erected at both longitudinal ends of the bottom plate 36.
A motor mounting plate 39 for mounting a fixing drive motor 82 is mounted on one side plate 37 of the base frame 35.

One end of the support shaft 51 of the press roller 50 opposite to the motor mounting plate 39 penetrates the side plate 37, and a press roller gear 54 is attached to the end thereof. Further, a support shaft 111 extending parallel to the press roller 50 is provided on the downstream side (front side in the figure) of the press roller 50. Both ends of the support shaft 111 pass through both side plates 37, and a transmission gear 113 is provided at one end on the side of the motor mounting plate 39 via a one-way clutch 112. The other end of the support shaft 111 is provided with a rotation imparting gear 110 that engages with the press roller gear 54 when the press roller 50 is at the retracted position.

Next, a mechanism for rotating the heat roller 40 will be described. FIG. 5 is a plan view of the fixing device 30. In FIG. 5, the heat roller 40 and the upper frame 120 are omitted. The direction in which the recording paper is conveyed is indicated by an arrow. The motor mounting plate 39 is provided in parallel with the side plate 37, and the fixing drive motor 82 is mounted on the motor mounting plate 39 with the output shaft 142 protruding toward the side plate 37. A motor gear 143 is fixed to the output shaft 142 of the fixing drive motor 82, and the motor gear 143 is
And a first gear 145 rotatably provided around a support shaft 144 provided between the motor and the motor mounting plate 39. The support shaft 144 is provided with a second gear 146 that rotates integrally with the first gear 145. Second gear 14
6 is a third gear 1 provided rotatably with respect to the side plate 37.
And 47 are engaged. The third gear 147 is engaged with the roller gear 44 (FIG. 3) of the heat roller 40 described above.

The transmission gear 113 fixed to the support shaft 111 is further engaged with the third gear 147. When the heat roller 40 rotates, the rotation imparting gear 110 rotates via the transmission gear 113 and the support shaft 111.

Next, a mechanism (opening / closing mechanism 33 in FIG. 1) for opening and closing the space between the heat roller and the press roller will be described. On the other hand, as shown in FIG. 5, in addition to the third gear 147, a fourth gear 148 rotatably supported by the side plate 37 is engaged with the second gear 146. 4th
The gear 148 is engaged with the sixth gear 150 via a fifth gear 149 fixed coaxially. 6th gear 150
Is connected to the camshaft 152 via the clutch 151. That is, by turning on / off the clutch 151, the camshaft 152 is rotated using the driving force of the fixing drive motor 82.

The camshaft 152 is connected to the base frame 3
5 extends between the two side plates 37, 37, and near both ends thereof, a first roller for driving the press roller 50 up and down is provided.
The disc cams 153 and 153 are fixed. Also,
An encoder wheel 192 for detecting the rotation angle of the camshaft 152 is fixed to a substantially central portion in the longitudinal direction of the camshaft 152, and a photo interrupter 193 for reading the encoder wheel 192 is provided on the bottom plate 36 of the base frame 35. Are formed.

A second disk cam 155 for swinging the swing holder 22 for holding the corona charger of the transfer section 20 (FIG. 1) is fixed substantially at the center of the cam shaft 152. A cam follower 194 provided on a slide arm 23 extending toward the transfer unit 20 is in contact with the second disc cam 155, and the rotation of the cam shaft 152 moves the slide arm 23 in the vertical direction in the figure. .

FIG. 6 is a side view showing the fixing device 30. In FIG. 6, the side plate 37 on the near side in the figure is removed and shown. A swing arm 161 for ascending and descending the press roller 50 is swingably supported on a support shaft 160 protruding from the side plate 37. At one end of the swing arm 161, a radial bearing 161 a that rotatably holds the support shaft 51 of the press roller 50 is provided.

Then, the rocking arm 16 is located between the rocking arm 161 and the front and rear sides in the figure via a compression spring 94b.
A pair of plates 169 and 162 that swings integrally with the plate 1 are provided. The plate pairs 169 and 162 are provided with cam followers 163 that engage with the disc cams 153. The plate 162 is urged by a tension spring 164 having one end fixed to the bottom plate 36 so that the cam follower 163 and the disk cam 153 are always engaged.
In this manner, the plate pair 169, 1 integrated with the cam follower 163 by the rotation of the disc cam 153.
62 swings, and this rotational motion is transmitted to the swing arm 161 via the compression spring 94b, and the swing of the swing arm 161 causes the press roller 50 to move up and down.

When the disc cam 153 comes into contact with the cam follower 163 at the maximum radius (point D), the space between the heat roller 40 and the press roller 50 is closed with the recording paper sandwiched therebetween (FIG. 6A). Cam follower 1 with radius (point A)
When the pressing roller 50 comes into contact with the heat roller 4
It is determined to be the most distant from 0 (FIG. 6B). Thus, by the rotation of the disc cam 153,
The press roller 50 moves up and down between the operating position and the retracted position.

It should be noted that a guide plate 90 for guiding the recording paper guided to the fixing device 30 from below is swingably provided in conjunction with the swing arm 161. Both ends of the guide plate 90 are bent in a U-shape to form side plates 92,
The side plates 92 are supported by a support shaft 91 provided on the side plate 37. The guide plate 90 is provided with a contact piece 93 that contacts the upper end of the swing arm 161, and a tension spring 94 a is provided between the contact piece 93 and the swing arm 161. When the swing arm 161 is at the retracted position (FIG. 6B), the guide plate 90 guides the recording paper so as not to contact either the heat roller 40 or the press roller 50.

Next, the opening and closing operation of the heat roller and the press roller according to the present embodiment will be described. As shown in FIG. 5, the transmission gear 113 is engaged with the third gear 147. Therefore, when the fixing drive motor 82 rotates and the heat roller 40 rotates via the first gear 145 to the third gear 147, the support shaft 111 and the rotation applying gear 110 rotate via the transmission gear 113.

FIG. 7 is a side sectional view of the fixing device 30.
When the press roller 50 is at the retracted position, the press roller gear 54 is engaged with the rotation applying gear 110. Therefore, the rotation of the rotation imparting gear 110 causes the press roller 50 to rotate via the press roller gear 54. In addition,
At this time, the rotation direction of the press roller 50 is the same as the recording paper conveyance direction, as indicated by the arrow in the figure.

After the rotation of the heat roller 40 starts, the clutch 151 (FIG. 5) operates to swing the swing arm 161.
The press roller 50 is moved from the retracted position to the operation position. When the press roller 50 moves from the retracted position,
The engagement between the press roller gear 54 and the rotation imparting gear 110 is released, and the press roller 50 moves toward the operation position while continuing to rotate by inertia. Then, the press roller 50 comes into contact with the recording paper while rotating, and sandwiches the recording paper with the heat roller 40. Therefore, the occurrence of skew or jitter of the recording paper caused by the contact between the recording paper and the stopped press roller 50 is prevented.

As described above, according to the fixing device of this embodiment, the press roller 50 reaches the operating position and the heat roller 5
The press roller 50 has already been rotated when the recording paper is sandwiched between 0 and 0. Accordingly, the occurrence of skew or jitter of the recording paper caused by the contact between the recording paper and the stopped press roller 50 is prevented.

Since a one-way clutch 112 (FIG. 4) is provided between the transmission gear 113 and the support shaft 111, the support shaft 111 and the rotation imparting gear 110 rotate the heat roller 40 in the forward direction. Only rotate when you do. Further, the peripheral speed of the rotation imparting gear 110 (rotational peripheral speed in a pitch circle)
V is V ≦ W with respect to the peripheral speed W of the press roller gear 54 when the press roller 50 and the heat roller 40 are in contact with each other.
It is set to be. Therefore, the press roller 50
Moves from the operating position to the retracted position, and the press roller gear 5
When 4 re-engages with rotation imparting gear 110, one-way clutch 112 (FIG. 4) is free and press roller gear 54 can smoothly engage rotation imparting gear 110.

Next, a second embodiment of the present invention will be described. In the first embodiment, an initial rotation speed is given to the press roller 50 by rotating the rotation imparting gear 110. On the other hand, in the second embodiment, the rotation imparting gear 210 locked in one direction is stopped. And the initial rotation speed is given to the press roller 50 by using the driving force of the rise of the press roller 50.

FIG. 8 shows a fixing device 230 according to the second embodiment.
FIG. When the press roller 50 is in the retracted position, the rotation imparting gear 21 engaged with the press roller gear 54
Numeral 0 is supported by a support shaft 211 provided on the side plate 37, and a one-way clutch 212 is provided between the support shaft 211 and the rotation applying gear 210.

FIG. 9 is a schematic side view of the fixing device 230. The rotation giving gear 210 includes a one-way clutch 212
Thus, it is rotatably supported only clockwise in the figure. Unlike the first embodiment, no transmission gear or the like for rotating the rotation imparting gear 210 is provided. The configuration other than the above is the same as that of the first embodiment.

Next, the opening and closing operation of the press roller and the heat roller in the fixing device of the second embodiment will be described. Even if the fixing drive motor 82 (FIG. 8) operates and the heat roller 40 starts rotating, the rotation imparting gear 210 engaged with the press roller gear 54 is not rotating.
The press roller 50 is stopped (FIG. 9A).

Subsequently, the clutch 151 (FIG. 8) is operated, and the swing arm 161 starts swinging. When the press roller 50 rises, the rotation imparting gear 210 does not rotate counterclockwise in the figure, so the press roller gear 54 is rotated in the direction of the arrow in the figure. That is, the initial rotation speed is given to the press roller gear 54, that is, the press roller 50, by using the driving force when the press roller 50 is raised (FIG.
(B)). Then, as in the first embodiment, the press roller 50 moves toward the operation position while continuing to rotate by inertia, and sandwiches the recording paper with the heat roller 50.

Since the rotation imparting gear 210 can rotate only clockwise, when the press roller 50 moves from the operating position to the retracted position, the rotation imparting gear 210 rotates clockwise to the press roller gear 54. Engage again.

As described above, according to the second embodiment, similarly to the first embodiment, since the press roller 50 reaches the operation position while rotating, the recording paper and the stopped press roller 50 are separated. The occurrence of skew or jitter of the recording paper caused by the contact is prevented. Further, according to the second embodiment, since the initial rotation is given to the press roller by using the elevation of the press roller, a mechanism for rotating the rotation applying gear 210 is not required, and the first
The configuration is simpler than that of the embodiment.

In the second embodiment, the rotation imparting gear 210 is disposed at a position where the press roller 50 is engaged with the press roller gear 54 when the press roller 50 is at the retracted position. It may be arranged at a position where it engages with the press roller gear 54 while moving to the operation position.

Next, a third embodiment of the present invention will be described. In the first and second embodiments, the rotation imparting gear gives the press roller an initial rotation speed. On the other hand, in the third embodiment, the rotation imparting roller that comes into contact with the surface of the press roller causes the press roller to have the initial rotation. It gives speed.

FIG. 10 shows a fixing device 33 according to the third embodiment.
0 shows a press roller 350 used. Unlike the press roller 50 of the first and second embodiments, the press roller 350 of the third embodiment has no gear. The press roller 350 is fixed to the fixed support shaft 351.
And a cylindrical portion 353 rotatably held around the fixed support shaft 351 via a radial bearing 352. The surface of the cylindrical portion 353 is made of an elastic member such as rubber.

FIG. 11 shows a fixing device 33 according to the third embodiment.
FIG. 2 is a view of the apparatus viewed from the downstream side in the transport direction. Press roller 3
On the downstream side (front side in the figure) of the pair 50, a pair of rotation applying rollers 310 abutting on the press roller 350 at the retracted position.
Is provided. Support shaft 311 of rotation applying roller 310
Is rotatably supported by a bearing 312 provided on the side plate 37. Fixing drive roller 82 of support shaft 311
A transmission gear 313 is provided at one end on the side via a one-way clutch 314, and the transmission gear 313 is connected to the third gear.
It is engaged with the gear 147. The configuration other than the above is the same as that of the first embodiment.

Next, the opening and closing operation of the heat roller and the press roller in the fixing device of the third embodiment will be described. As shown in FIG. 11, since the transmission gear 313 is engaged with the third gear 147, when the fixing drive motor 82 rotates, the third gear 147, the transmission gear 313, and the support shaft 31 are rotated.
The rotation applying roller 310 rotates through the rotation of the roller 1.

FIG. 12 shows a fixing device 33 according to the third embodiment.
0 is a side sectional view. As shown in FIG. 12, the rotation imparting roller 310 is arranged so as to come into contact with the surface of the press roller 350 when the press roller 350 is at the retracted position. The rotation direction of the rotation applying roller 310 is clockwise in the figure. Therefore, rotation in the direction of the arrow in the figure is given to the press roller 350 by the rotation imparting roller 310.

After the rotation of the heat roller 40 is started, the clutch 151 (FIG. 11) is operated, and the press roller 350 is lifted from the retracted position by the swing of the swing arm 361, and the press roller 350 is separated from the rotation applying roller 310. Move toward the operating position while continuing to rotate due to inertia. Then, the press roller 350 reaches the operation position while rotating, and sandwiches the recording paper with the heat roller 350. Therefore, the recording paper and the stopped press roller 3
The occurrence of skew or jitter of the recording paper caused by the contact with the recording paper 50 is prevented.

In the first embodiment described above, the swing arm 161 for raising and lowering the press roller is provided with a radial bearing for rotatably supporting the press roller. In the form, the press roller 350
Since the fixed support shaft 351 does not rotate, the swing arm 361
Is configured to abut against and lift the fixed support shaft 351 of the press roller 350 from below.

As described above, according to the fixing device of the third embodiment, similarly to the first and second embodiments, the press roller 350 rotates to reach the operation position while rotating, and the recording paper , The skew or jitter of the recording paper caused by the contact between the recording paper and the stopped press roller 350 is prevented. Further, since there is no need to provide a gear for the press roller, the structure for holding the press roller and the press roller can be simplified.

Next, a fourth embodiment of the present invention will be described. In the third embodiment, an initial rotation speed is given to the press roller by rotating the rotation imparting roller. On the other hand, the fourth embodiment uses a fixed rotation imparting roller and utilizes the rise of the press roller. This gives the press roller an initial rotation speed.

FIG. 13 shows a fixing device 43 according to the fourth embodiment.
FIG. 2 is a view of the apparatus viewed from the downstream side in the transport direction. Press roller 3
The rotation applying roller 410 provided so as to come into contact with the surface of the press roller 350 when the 50 is in the retracted position,
7 is supported by a support shaft 411 provided on the support shaft 41.
Is fixed to the side plate 37. A notch is formed at one end of the support shaft 411 so that the support shaft 411 does not rotate, and the notch is inserted into a hole 414 formed in the side plate 37 in a substantially D shape. Unlike the third embodiment, a transmission gear or the like for rotating the rotation applying roller 410 is not provided. The configuration other than the above is the same as the third embodiment.

Next, the opening and closing of the press roller and the heat roller according to the fourth embodiment will be described. FIG. 14 is a side sectional view of a fixing device 430 according to the fourth embodiment. The fixing drive motor 82 (FIG. 13) operates, and the heat roller 40
Is rotated, the press roller 350 is stopped because the rotation applying roller 410 is fixed (FIG. 14).
(A)).

After the rotation of the heat roller 40 is started, the clutch 151 (FIG. 11) is operated, and the swing arm 361 starts swinging. Here, when the press roller 350 rises from the retracted position, the rotation applying roller 410 does not rotate, so the press roller 350 is rotated in the direction of the arrow in the figure (FIG. 14B). That is, the rotation speed of the press roller 350 is given to the press roller 350 using the rise of the press roller 350. Then, similarly to the third embodiment, the press roller 3
The reference numeral 50 moves to the operation position while continuing rotation by inertia, and sandwiches the recording paper between the heat roller 40 and the heat roller 40.

As described above, according to the fourth embodiment, similarly to the first to third embodiments, the press roller 3
Since the rotating member 50 reaches the operation position while rotating, the skew or jitter of the recording sheet caused by the contact between the recording sheet and the stopped press roller 350 is prevented. Further, according to the fourth embodiment, a mechanism for rotating the rotation applying roller 410 is not required, and the configuration is simplified as compared with the third embodiment.

In the fourth embodiment, the rotation applying roller 410 is disposed at a position where the rotation applying roller 410 comes into contact with the press roller 350 when the press roller 350 is at the retracted position.
The press roller 350 may be disposed at a position where the press roller 350 temporarily engages with the press roller 350 while moving from the retracted position to the action position. Further, the support shaft 411 and the rotation applying roller 4
By arranging the one-way clutch between the rollers 10, it is possible to prevent a braking effect acting on the press roller 350 when the press roller 350 and the rotation applying roller 410 come into contact with each other.

Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the rotation of the press roller 350 is provided by using the movement of the slide arm 23 for retracting the corona charger in the transfer section in conjunction with the press roller 350.

FIG. 14 shows a fixing device 53 according to the fifth embodiment.
FIG. As in the first embodiment, a slide arm 23 extending toward the transfer unit 20 is provided to swing the corona charger of the transfer unit 20 (FIG. 1) in conjunction with the movement of the press roller 350.

As described above, the cam follower 194 is provided at the end of the slide arm 23.
94 contacts the second disk cam 155. Then, by the rotation of the camshaft 152, the slide arm 23 is moved in the vertical direction in the figure.

Here, on the downstream side (lower side in the drawing) of the slide arm 23 in the transport direction, the press roller 3 in the retracted position is located.
A contact portion 510 made of rubber, which is in contact with the lowest point of 50, is provided. The rotation imparting gear and the rotation imparting roller as in the first to fourth embodiments are not provided. Except for the above configuration, it is the same as the fourth embodiment.

Next, the opening and closing of the heat roller and the press roller by the fixing device of the fifth embodiment will be described. After the rotation of the heat roller 40 starts, the clutch 151 operates, and the engagement of the first gear 145 to the sixth gear 149 causes
The camshaft 152 rotates. When the camshaft 152 rotates, the swing arm 361 configured to swing integrally with the cam follower 163 via the compression spring 94b by engagement with the cam follower 163 moves the support shaft 160.
To move the press roller 350 toward the operation position. At the same time, the engagement of the second disk cam 155 and the cam follower 104 causes the slide arm 23
Slides upstream (from bottom to top in the figure) to move the corona charger 19 (FIG. 1) to the operative position.

FIG. 16 shows a fixing device 53 according to the fifth embodiment.
0 is a side sectional view. When the slide arm 23 slides upstream (from the bottom to the right in the figure), the contact between the contact portion 510 provided on the downstream end of the slide arm 23 and the press roller 350 causes the press roller 350 to rotate counterclockwise. A rotation around (that is, a recording paper conveyance direction) is given. Then, the press roller 350 reaches the operation position while rotating by inertia, and sandwiches the recording paper with the heat roller 350. Therefore, the occurrence of skew or jitter of the recording sheet caused by the contact between the recording sheet and the stopped press roller 350 is prevented.

As described above, according to the fixing device of the fifth embodiment, as in the first to fourth embodiments, the press roller 350 reaches the operation position in a state where the press roller 350 has already been rotated, and the heat roller 40 and the heat roller 40 reach the operation position. Since the recording paper is sandwiched, skewing of the recording paper or occurrence of jitter is prevented. In addition, this fifth
In the embodiment, the contact portion 510 is
Is only required to be provided, so that the number of parts can be reduced.

Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, an initial rotation speed is given to the press roller by using a fan for cooling the press roller. FIG. 17 is a diagram illustrating the press roller 650 in the fixing device 630 according to the sixth embodiment with a part cut away. As shown in FIG.
50 includes a fixed support shaft 651 and a cylindrical portion 653 rotatably held around the fixed support shaft 651 via a radial bearing 652. Impellers 655 are provided at both axial ends of the cylindrical portion 653. Is provided.

FIG. 18 shows a fixing device 63 according to the sixth embodiment.
0 is a side sectional view. On the upstream side of the press roller 650, a fan 610 for running the press roller 650 is used.
Is provided. The shape of the impeller 655 of the press roller 650 is determined so that the press roller 650 rotates in the direction indicated by the arrow in FIG. The configuration other than the above is the same as the third embodiment.

With such a configuration, the press roller 650 moves to the operating position while rotating by receiving air blow from the fan 610, and sandwiches the recording paper with the heat roller 40. As described above, according to the fixing device of the sixth embodiment, similarly to the first to fifth embodiments, the press roller 650 reaches the operation position while rotating, and the heat roller 4 rotates.
Since the recording paper is sandwiched between 0 and 0, the occurrence of skew or jitter of the recording paper is prevented. In the sixth embodiment, when the fan 610 is operating when the press roller 650 is in the retracted position, the press roller 65 is not operated.
Since 0 is constantly rotating, there is also an effect that the press roller 650 is uniformly air-cooled throughout.

In each of the above embodiments, if the rotational peripheral speed of the press roller immediately before contact with the heat roller is too slow compared to the rotational peripheral speed of the heat roller (or the recording paper conveyance speed), The effect of preventing skew and jitter is small. If the speed is too fast, the recording paper is pulled when the press roller comes into contact with the heat roller, causing jitter instead. Therefore, the rotation peripheral speed of the press roller immediately before contact with the heat roller is -50% to + 50%, more preferably -20% to +2, with respect to the rotation peripheral speed of the heat roller (or recording paper conveyance speed).
Set to the range of 0%.

Table 1 below shows the results of an experiment in which the relationship between the rotational speed of the press roller immediately before contact with the heat roller and the effect of preventing skew jitter was examined. In Table 1, the peripheral speed of the press roller is represented by a value relative to the peripheral speed of the heat roller. ◎ indicates very good, ○ indicates good, △ indicates slight effect, and × indicates bad (recording paper jam occurs).

[0081]

[Table 1] Press roller peripheral speed Skew Jitter Remarks -60% ○ △ Jitter reduction effect is not stable -40% ○ ○ -20% ◎ ◎ 0% ◎ ◎ + 20% ◎ ◎ + 40% ○ ○ + 60% ○ × Jams frequently occur

If the press roller continues to be rotated by the initial rotation applying means when the heat roller contacts the press roller, a shock is applied to the recording paper when the heat roller contacts the press roller to cause jitter. Let me do it. Therefore, before the press roller contacts the heat roller, the press roller is separated from the initial rotation speed applying means or the operation of the initial rotation speed applying means is stopped, so that the press roller is rotated by inertia. When the press roller comes into contact with the heat roller, it is preferable that the heat roller be driven to rotate.

[0083]

As described above, the fixing device of the present invention is provided with the initial rotation speed applying means for applying the initial rotation speed to the press roller when the press roller moves from the retracted position to the operating position. When the press roller rotates, it reaches the operation position and sandwiches the recording paper with the heat roller. Therefore, the occurrence of skew or jitter of the recording paper caused by the contact of the stopped press roller with the conveyed recording paper is prevented. In particular, when continuous recording paper is used as recording paper, skew is prevented from accumulating and large skew is prevented.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a basic configuration of a printer.

FIG. 2 is a perspective view illustrating a heat roller, a press roller, and a frame in the fixing device.

FIG. 3 is a front view showing the heat roller and the press roller of FIG. 2 and a frame that holds them.

FIG. 4 is a front view showing the fixing device according to the first embodiment of the present invention.

FIG. 5 is a plan view illustrating the fixing device of FIG. 3;

FIG. 6 is a side sectional view showing the fixing device of FIG. 3;

FIG. 7 is a side sectional view showing the fixing device of FIG. 3;

FIG. 8 is a front view illustrating a fixing device according to a second embodiment.

9 is a side sectional view showing the fixing device of FIG.

FIG. 10 is a diagram illustrating a structure of a press roller of a fixing device according to a third embodiment.

FIG. 11 is a front view illustrating a fixing device according to a third embodiment.

12 is a side sectional view showing the fixing device of FIG.

FIG. 13 is a front view illustrating a fixing device according to a fourth embodiment.

14 is a side sectional view showing the fixing device of FIG.

FIG. 15 is a plan view illustrating a fixing device according to a fifth embodiment.

16 is a side sectional view showing the fixing device of FIG.

FIG. 17 is a diagram illustrating a structure of a press roller in a fixing device according to a sixth embodiment.

18 is a side sectional view showing the fixing device of FIG.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 printer 23 slide arm 30, 230, 330, 430, 530, 630 fixing device 40 heat roller 50, 350, 650 press roller 82 fixing drive motor 110, 210 rotation applying gear 111, 211 support shaft 120 upper frame 130 lower frame 151 Clutch 152 Camshaft 153 First disc cam 155 Second disc cam 161, 361 Swing arm 163 Cam follower 310, 410 Rotation applying roller 311, 411 Support shaft 510 Contact portion 610 Fan 655 Impeller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kasumi Yamamoto 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. (72) Inventor ▲ Yana ▼ Shima Shima 2 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. (72) Inventor Hiroyuki Saito 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd.

Claims (13)

[Claims] 1. A fixing device for fixing an image on a recording sheet, comprising: a heat roller having a built-in heat source; an operation position for pressing the recording sheet between the heat roller; A press roller movable between the retracted position, a rotating unit for rotating the heat roller, and moving the press roller between the operating position and the retracted position to open and close the two rollers. Opening / closing means, wherein the opening / closing means moves the press roller to the operation position after the heat roller starts rotating, and when the press roller is moved to the operation position by the opening / closing means, And a pressurizing means for applying an initial rotational speed in a predetermined direction to the press roller. And a drive gear that engages with a driven gear provided on the press roller when the press roller is at the retracted position or between the retracted position and the operating position. The fixing device according to claim 1, wherein 3. The fixing device according to claim 2, wherein the driving gear is driven by the rotating unit. 4. The fixing device according to claim 4, wherein the drive gear is locked from rotating in the predetermined direction. 5. The method according to claim 1, wherein the initial rotation speed applying means is a contact roller that comes into contact with the surface of the press roller when the press roller is at the retracted position or between the retracted position and the operating position. The fixing device according to claim 1, wherein: 6. The fixing device according to claim 5, wherein the contact roller is driven by the rotating unit. 7. The fixing device according to claim 5, wherein the contact roller is stopped from rotating in at least one direction. 8. The rotation initial speed applying means is a slide arm that contacts the surface of the press roller when the press roller is at the retracted position and moves in a tangential direction of the press roller at the contact position. The fixing device according to claim 1, wherein: 9. The slide arm according to claim 8, wherein the slide arm is used to move another member between an operating position and a retracted position in conjunction with the opening / closing means. 3. The fixing device according to claim 1. 10. The rotation initial speed applying means is provided on the press roller for blowing air toward the press roller and receiving the air from the fan to rotate the press roller in a predetermined direction. The fixing device according to claim 1, wherein the fixing device is a mounted impeller. 11. The impeller is provided at both ends in the axial direction of the press roller.
0. The fixing device according to 0, 12. The method according to claim 1, wherein the rotation peripheral speed of the press roller immediately before the contact of the press roller with the heat roller is in the range of −50% to + 50% with respect to the rotation peripheral speed of the heat roller. The fixing device according to claim 1, wherein: 13. The method according to claim 1, wherein the rotation speed applying means stops applying the rotation speed to the press roller or separates from the press roller before the press roller comes into contact with the heat roller. The fixing device according to claim 1, wherein: