JP3016885B2 - Fixing device for image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device in an image forming apparatus such as a copying machine or a printer, and more particularly to a heating roller being slightly separated from a pressure roller in accordance with an operation of opening and closing an upper frame of the image forming apparatus. The present invention relates to a fixing device of an image forming apparatus, which is provided with a mechanism for performing the fixing operation and a unit that largely separates both rolls during maintenance of the fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic process, such as a copying machine or a printer, a toner image is formed on an image carrier, the toner image is transferred to a sheet, and fixed through a fixing device. And means for making a copy. The image forming apparatus, in the case of a small device, provided the upper member of the paper transport path so that it can be opened together with the upper frame bordering the paper path, when a jam or the like occurs in the paper path, By opening the upper frame, the jam paper can be easily removed.

On the other hand, in a relatively large-sized apparatus, a guide plate or the like constituting a paper path is provided so as to be openable and closable, and means for removing jammed paper is used. Further, in the device in which the upper frame is provided so as to be openable and closable, while the upper frame is opened in an alligator-like shape, it is possible to perform work such as maintenance on each component member. In such an image forming apparatus, means for pulling out a photosensitive member, a fixing device, and other members to the front side of the apparatus and performing maintenance is used.

A fixing device used in the image forming apparatus generally includes a heating roll having a built-in heat-generating member such as a lamp, and a pressure roll disposed opposite to the heating roll and in contact with a certain pressing force. A means for melting the toner by pressing a sheet carrying a toner image between the two rolls, and pressing and fixing the toner on the sheet is used. Apparatus incorporating the heat roll type fixing device into an alligator type image forming apparatus, for example,
A structure as disclosed in Japanese Utility Model Laid-Open No. 63-48749 is known. In the conventional fixing device, a mechanism is provided to separate the heating roll from the pressure roll when the upper frame is opened, and when a jam occurs in the fixing device, the upper frame of the image forming apparatus is moved. By opening the sheet, the sheet can be easily pulled out from the fixing device.

When a mechanism for opening and closing the paper path of the fixing device is provided in accordance with the operation of opening and closing the upper frame, if the upper frame is closed with respect to the lower frame, the heating roll of the fixing device and The nip state with the pressure roll can be easily set, and the image forming apparatus can be operated.

[0006]

However, in the above-described apparatus in which the two rolls of the fixing device are separated from and brought into contact with each other in conjunction with opening and closing of the upper frame of the conventional image forming apparatus main body, the heating of the upper portion of the fixing device is performed. There is a problem that it is difficult to set the nip state again after the roll is largely separated from the pressure roll. Further, in order to accurately regulate the roll members constituting the fixing device to the nip position, it is necessary to provide a large number of positioning members for each roll, which makes the fixing device complicated. There is a problem of becoming a mechanism.

In the fixing device, when a driving roller for a discharge roller is provided on an upper frame for a driven heating roll, there is a problem that the driving roller rubs an image surface of a copy. If the drive roller of the discharge roller device is arranged so as to be in contact with the back surface of the sheet in order to solve this problem, there arises a problem that the drive interlocking mechanism for each of those rollers becomes complicated. Further, when opening and closing the upper frame supporting the heating roll, a mechanism for interlocking each driving member is provided for each of the upper and lower frames, and such driving rollers are interlocked.
It is necessary to use a complicated mechanism.

Further, a guide plate member is disposed at a portion where a sheet carrying a toner image is introduced into a nip portion between upper and lower rolls of the fixing device, and the sheet is accurately introduced into a nip portion formed by both rolls. It is necessary to be done. However, in an apparatus using a mechanism capable of opening and closing the upper frame, in order to position the guide plate member with respect to the heating roll, it is necessary to accurately use a fixing member for the upper and lower frames of the fixing device. Required. However, when the heating roll is separated from the pressure roll, or when using means for pressing the pressure roll against the heating roll, the guide member follows the nip position because the nip position of both rolls changes. Therefore, there is a problem that it is difficult to set accurately.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem in the fixing device. The heating roll of the fixing device is changed to a pressure roll by following the opening and closing of the image forming apparatus main body which is opened and closed like an alligator. And a mechanism for opening the sheet slightly so that the sheet can be pulled out, and a mechanism for opening the sheet more widely, so that the drive can be easily connected. It is an object of the present invention to provide a drive mechanism that can be used, and to provide an apparatus that can easily perform positioning of a paper guide.

[0010]

According to the present invention, an upper frame of a main body of an image forming apparatus is provided so as to be opened and closed like a crocodile mouth with respect to a lower frame of the main body via a support shaft. The present invention relates to a fixing device disposed between an image transfer unit and a discharge unit. The fixing device according to claim 1, wherein the fixing device includes an upper frame of the fixing device that supports a heating roll disposed via a support shaft with respect to a lower frame of the fixing device, and an upper frame of the fixing device. A discharge roller device supported on each of the lower frames, a pressure roll supported via a pressing lever pivotally supported by the lower frame of the fixing device, an end of the lever, and an upper frame of the fixing device. A spring provided between the locking step portions of the rear arm to be provided, the pressing force being adjustable by changing the locking position of the rear arm with respect to the locking step portion, and a fixing device supporting the heating roll. A pressing projection that is provided to protrude above the upper frame and is exposed upward from the cover member of the fixing device, and the pressing projection is pressed by an upper frame of the main body of the image forming apparatus. In, characterized in that it allows the operation of the fixing.

According to a second aspect of the present invention, when the upper frame of the main body of the image forming apparatus is opened, the pressing action of the main body of the image forming apparatus against the pressing projection is stopped, and the nip of the discharge roller device is released. By weakening the nip pressure of the fixing roll so as to cope with drawing out of the paper and opening the upper and lower frames of the fixing device via hinges, the heating roll and the pressing roll are separated from each other so that maintenance can be dealt with. It is characterized by.

According to a third aspect of the present invention, the driving means for driving the heating roll and the driving roller of the discharge roller member in conjunction with each other via an input gear provided on a support shaft of an upper frame of the fixing device, comprises: A transmission gear member is arranged between a drive gear for the roll and a drive gear for the drive roller of the discharge roller, and the input gear, one of the transmission gears, and the gear of the drive roller of the discharge roller device are aligned in a straight line. It is characterized by being arranged in.

By configuring the fixing device as described above, in the present invention, the mechanism for supporting the heating roll and the pressure roll of the fixing device can be simplified, and the heating roll is used in the normal jam processing and the like. Can be opened slightly, and when the fixing device is closed again, each roll can be easily positioned. Also, when performing maintenance on the fixing device, the upper frame can be opened widely. Further, in the present invention, the adjustment of the nip pressure between the two rolls can be easily performed by changing the locking position of the spring, and the configuration of the supporting mechanism of the pressing roll for that purpose is simplified. can do.

In addition to the above effects, in the driving system of the fixing device of the present invention, the driving gear of the discharge roller and the transmission gear for transmitting the driving force to the gear are connected to the shaft supporting the upper and lower frames. By arranging the gears linearly, the meshing state of the gears can be easily set when the frame is closed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The fixing device of the present invention will be described with reference to the illustrated example. The fixing device 1 of the present invention shown in FIG.
A heating roll 2 having a heating source such as a halogen lamp therein, as in a general heating roll type fixing device;
A pressure roll 5 which comes into contact with the heating roll 2 at a predetermined pressure. In the two rolls 2 and 5, the heating roll 2 is supported by an upper frame 15, and the frame 15 is provided to be openable and closable with respect to the lower frame 10 via a support shaft 16. The lower frame 10 is provided with a pressing lever 12 via a support shaft 11 at an upstream portion in the paper transport direction, and a bearing 13 provided on the pressing lever 12 supports the bearing member 6 of the pressure roll 5. are doing. In the fixing device 1 of the present invention described below, a sheet is fed from the right side of FIG. 1 to the fixing device, and is discharged by the discharge roller device 25 on the left side of FIG.

The upper frame 15 is connected to the lower frame 1
When opening from zero, the sling 20 urges the upper frame in the opening direction, so that the operation of opening the upper frame can be easily performed. Further, a pressing lever 12 supporting the pressure roll 5 has a locking portion 14 at the other end corresponding to the support shaft 11 disposed upstream of the lower frame 10.
Is arranged, and a spring 20 is arranged between the rear arm 18 protruding from the upper frame 15 to urge the pressure roll 5 toward the heating roll 2. In the fixing device of the present invention, a pressing projection 17 disposed at an end of the upper frame 15 is pressed by the upper frame of the image forming apparatus so that the two roll members of the fixing device nip the sheet. Is set. Then, with the upper frame of the image forming apparatus opened, the heating roll is swung in a direction to separate from the pressure roll.

A discharge roller device 25 is disposed downstream of a nip portion formed by the heating roll and the pressure roll. A drive roller 26 of the discharge roller device 25 is mounted on the lower frame 10 by pinching. The rollers 27 are arranged with respect to the upper frame 15. Then, with the upper frame closed, the pinch roller is positioned with respect to the drive roller, and the fixed sheet is discharged while being nipped by the discharge roller device.

In addition to the above configuration, in the fixing device of the present invention, a cover member 21 is provided for the upper frame 15, and the cover member 21 can perform a heat insulating function at the upper part of the fixing device. Like that. At the end of the cover member 21 on the upstream side, a member 22 that is greatly curved downward is disposed, and a receiving member 23 from the lower frame 10 is disposed corresponding to the end of the member 22. By arranging the end portion 22 of the cover member and the receiving member 23, when the upper frame of the image forming apparatus is opened and the upper frame 15 is swung through the support shaft 16, the heating roll is applied. With a slight distance from the pressure roll,
The upper and lower members 22, 23 are engaged with each other in a state where they abut.

In the state where the cover member 21 is removed, there is no member to be engaged with the receiving member 23 provided on the lower frame 10, so that the upper frame 15 is widely opened via the support shaft 16 and 5 and the like, and the work of removing each component supported by the lower frame can be easily performed. Therefore,
In the fixing device of the present invention, by removing the cover member provided for the upper frame, it is possible to perform operations such as maintenance on the internal mechanism of the fixing device while the upper frame is widely opened. it can.

In the fixing device 1, in order to adjust the nip pressure between the heating roll 2 and the pressure roll 5, the tension of the spring 20 is adjustable. In order to adjust the tension of the sling, a rear arm 18 is provided upstream of the upper frame 15.
As shown in FIG. 2, a locking step 19 provided with a plurality of steps is provided for 8. The locking step 19 includes a portion for hooking a locking member at the upper end of the spring 20,
A step is formed so as to be lower at the tip, and the tension of the spring is changed by locking the end of the spring 20 at an arbitrary position on the step. Therefore, in the present invention, the nip pressure between the two fixing roll members can be arbitrarily adjusted only by changing the locking position of the spring.

(Driving Mechanism of Roll of Fixing Device) In the fixing device of the present invention, as shown in FIG. 3, a driving device for the heating roll 2 is used to drive a driving roller 26 of a discharge roller device 25. Is used. FIG. 3
In the example shown in (1), the drive roller 26 of the discharge roller device 25 is configured to be in contact with the back surface of the sheet, and prevents the drive roller 26 from rubbing the image surface of the sheet. In addition, it is possible to prevent the image plane from being disturbed.

In the driving device 30 of the present invention, the input gear 31, the heating roll gear 32, the intermediate gear 33, and the input gear 31 are arranged coaxially with the support shaft 16 connecting the upper and lower frames 10, 15.
Means for transmitting the driving force to the gear 34 of the driving roller 26 via the transmission gear 35 is used. Of the gears, only the gear 34 of the drive roller 26 is supported by the lower frame 10, but the other gears are supported by the upper frame 15. The driving gear 32 of the heating roll is driven via the input gear 31, and the driving force is transmitted from the gear 32 to the gear 34 of the driving roller of the transport roller device via two gears 33 and 35. I have.

Of the gears, the transmission gear 35 is a bracket 3 projecting downward from the upper frame 15.
8, the gear 35 is separated from and brought into contact with the gear 34 of the roller 26 when the upper frame 15 is opened and closed. In the driving device of the present invention, as shown, the support shaft 16, the shaft 37 of the transmission gear 35, and the shaft 28 of the drive roller are arranged so as to be located on a straight line.

As described above, the three shafts are arranged in a straight line, and in the present invention, as shown in FIG. 4, by closing the upper frame 15, the gear 34 in the fixed position is closed. Thus, when the transmission gear 35 is engaged, the engagement can be performed while the transmission gear 35 is moved in the tangential direction of both gears. That is, when the upper frame is closed, the roller gear 34 at the fixed position is
The transmission gear 35 is moved from the position shown by the imaginary line in the figure to the position shown by the solid line, so that the teeth of the gear 35 with respect to the gear 34 can mesh without abutting on each other. Also, two gears 34 at the ends,
Since the support shaft 16 is positioned on the line connecting the rollers 35, when the heating roll of the fixing device and the driving roller of the transport roller device are driven, the operation of transmitting the driving force is performed well. .

In the drive mechanism shown in FIGS. 3 and 4, the transmission gear 35 is configured as shown in FIG. In the gear 35 shown in FIG. 5, a flange 36 is arranged at the center of the gear, and an intermediate gear 33 is engaged with the teeth on the outer side of the flange 36. Of gears 34 are arranged to be engaged. Therefore, the gear 35
The gear 35 can be supported on the shaft 37 without using means for fixing the gear 35 to the shaft 37, and the gear is prevented from coming off the shaft. The other gears 33 and 35 can be attached to the shaft using a fixing means 39 such as a C-ring.

(Supporting System for Inlet Chute) In the fixing device 1 of the present invention, an inlet chute 40 as shown in FIG. 6 is provided to guide a sheet.
The inlet chute 40 is swingably supported via a fulcrum 42 with respect to the upper frame 15 of the fixing device. As shown in FIG. Means for contacting each of the bearings 3 is used.

Generally, a guide plate member is arranged to guide a sheet carrying a toner image to a nip position between two rolls of a fixing device, and the leading end of the sheet is rolled by the guide plate member. It is necessary to provide good guidance for the nip position between them. However, in the case of the fixing device of the present invention, a mechanism for swinging the heating roll together with the upper frame is used.
Since the means for pressing the pressure roll toward the heating roll is used, there is a problem that the nip position between the two rolls is not constant. Therefore, in the present invention, in order to accurately guide the sheet with respect to the nip position between the two rolls, means for positioning the leading end of the inlet chute with respect to the heating roll is used, and the nip position is set in the fixing device frame. In this case, a means is used that enables the paper guided by the inlet chute to accurately follow the nip position even when the value changes.

That is, in the fixing device 1 of the present invention, as shown in FIG.
0 is supported on the upper frame via the fulcrum 42, and the tip of the chute 40 is fixed so as to abut against the heating roll. As a means for supporting the inlet chute, as shown in FIG. 7, a support is provided via a fulcrum 42, and a torsion spring 43 is provided with respect to the axis of the fulcrum, so that the inlet chute 40 shown in FIG. It can also be biased clockwise. Also, both ends of the inlet chute 40 are brought into contact with the bearing 3 of the heating roll 2 so that the tip of the chute is always located at a fixed position with respect to the heating roll 2. Therefore, by using the above-described chute holding means, the paper guided by the chute is always fed from a fixed position toward the nip position between the rolls, thereby improving the effect of fixing the image. Can be performed.

The above-described fixing device of the present invention can exhibit good performance of the fixing device by incorporating it into an image forming apparatus in a state where all the constituent elements are combined. That is, in the present invention,
The drive mechanism for the apparatus shown in FIG. 1 can be configured as shown in FIG. 3, and the paper guide member can be configured as a support type as shown in FIG. Further, each component of the present invention can be independently incorporated into a conventional fixing device, and even in such a case, the performance of the component can be exhibited. Further, the fixing device of the present invention can be used for any image forming apparatus such as a laser printer in addition to a copying machine using an electrophotographic method.

[0030]

Since the fixing device of the image forming apparatus of the present invention has the above-described structure, the mechanism for supporting the heating roll and the pressure roll of the fixing device can be simplified, and the ordinary device can be used. In jam processing etc., the upper frame supporting the heating roll can be opened slightly,
When the fixing device is closed again, each roll can be easily positioned. Also, the upper frame can be opened widely only when performing maintenance on the fixing device. Further, in the present invention, the adjustment of the nip pressure between the two rolls can be easily performed by changing the locking position of the spring, and the configuration of the supporting mechanism of the pressing roll for that purpose is simplified. can do.

In addition to the above effects, in the driving system of the fixing device of the present invention, the driving gear of the discharge roller and the transmission gear for transmitting the driving force to the gear are connected to the shaft supporting the upper and lower frames. When the frame is closed, the gears can be easily engaged when the frame is closed. Further, when the means for positioning the inlet chute with respect to the heating roll is used, the structure of the supporting means for the chute can be simplified, and the paper can be accurately guided toward the nip position between the rolls. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a fixing device of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a support member of a spring for setting a pressing force of a pressure roll.

FIG. 3 is a side view illustrating a configuration of a driving mechanism of the fixing device.

FIG. 4 is an explanatory diagram showing an arrangement relationship of a drive gear.

FIG. 5 is a front view showing a configuration of a transmission gear.

FIG. 6 is a side view showing a support state of the inlet chute.

FIG. 7 is a plan view showing a support state of the inlet chute.

[Signs in the figure]

 DESCRIPTION OF SYMBOLS 1 Fixing apparatus 2 Heating roll 5 Pressure roll 10 Lower frame 12 Press lever 15 Upper frame 25 Discharge roller device 30 Drive device 34 Drive roller gear 40 Inlet chute

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-156860 (JP, A) JP-A-60-19050 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (3)

(57) [Claims] An upper frame of a main body of the image forming apparatus;
A fixing device that is provided in a crocodile shape via a support shaft with respect to a lower frame of the main body and that is disposed between an image transfer unit and a discharge unit of the image forming apparatus; An upper frame of a fixing device that supports a heating roller disposed via a support shaft with respect to a lower frame of the device, a discharge roller device supported by each of the upper frame and the lower frame of the fixing device, and a lower portion of the fixing device A pressure roll supported via a pressing lever supported by a frame; and a rear arm disposed between an end of the lever and a locking step of a rear arm provided on an upper frame of the fixing device. A spring provided so as to be able to adjust the pressing force by changing a locking position with respect to the locking step portion, and a spring provided so as to protrude above an upper frame of the fixing device supporting the heating roll, And a pressing projection exposed upward from a cover member of the apparatus, wherein the fixing operation is enabled in a state where the pressing projection is pressed by an upper frame of the main body of the image forming apparatus. apparatus. 2. A pressing operation of the image forming apparatus main body against a pressing projection is stopped in a state where an upper frame of the main body of the image forming apparatus is opened, a nip of a discharge roller device is released, and a nip pressure of a fixing roller is released. The heating roll and the pressure roll are separated from each other by opening the upper and lower frames of the fixing device via hinges, so that maintenance can be dealt with. Item 2. A fixing device for an image forming apparatus according to Item 1. 3. A drive unit for driving the heating roll and a driving roller of a discharge roller member in conjunction with each other via an input gear provided on a support shaft of an upper frame of the fixing device, the driving unit comprising: a driving gear for the heating roll; A transmission gear member is disposed between the drive gear of the discharge roller and the drive roller, and the input gear and one of the transmission gears and the gear of the drive roller of the discharge roller device are arranged on a straight line. The fixing device for an image forming apparatus according to claim 1, wherein: