JP2002040864A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which doesn't require a large space and is provided with a jam removal mechanism, which doesn't require the labor for jam removal, in a fixing part. SOLUTION: A one-way clutch 33 is provided between a support shaft 32 of an ejection cover 31 and a support shaft gear 34. When the ejection cover 31 is displaced in the opening direction, torque of the support shaft 32 is transmitted to the support shaft gear 34 through the one-way clutch 33, and a lower fixing roll 23 is rotated in a carrying direction C. When the ejection cover 31 is displaced in the closing direction, the one-way clutch 33 is idled, and torque of the support shaft 32 is not transmitted to the support shaft gear 34. The ejection cover 31 is repeatedly displaced between closing position and the opening position to gradually send and take out a form P. The jamming form P can be sent and taken out by opening and closing the ejection cover 31. A space is not required because of the use of the one-way clutch 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a jam release mechanism of a fixing section for fixing a toner image transferred to a sheet.

[0002]

2. Description of the Related Art When a jam (paper jam) occurs in a fixing unit of an image forming apparatus, there is a manual dial as a mechanism for releasing the jam. In this type of image forming apparatus, the fixing roller and the rotating shaft of the manual dial are connected via, for example, a gear, and the jammed paper is sent out by rotating the fixing roller in the transport direction by rotating the manual dial, Pull out the paper and remove it.

[0003] The manual dial is formed somewhat large so that it is easy to grasp and can transmit a large torque.

[0004]

However, due to the structure, there are cases where the size of the manual dial cannot be sufficiently secured. In this case, it is difficult to grasp and the torque required to rotate the fixing roller increases. Further, with the downsizing of the image forming apparatus, for example, the manual dial may be located in a place where it is difficult to rotate the manual dial, such as the back side of the image forming apparatus. Therefore,
When the manual dial faces the wall, the manual dial must be rotated after the image forming apparatus is moved, which is very time-consuming.

SUMMARY OF THE INVENTION The present invention has been made under such a background, and has as its object to provide an image forming apparatus which does not require a large space and has a jam clearing mechanism in a fixing unit which does not require time for jam processing. And

[0006]

According to the first aspect of the present invention, there is provided a fixing roller for fixing and conveying a toner image transferred to a sheet, and the fixing roller. An opening / closing cover displaceable (for example, swingable or slidable) between a shielding position for shielding the outside from the outside and an opening position for opening the fixing roller to the outside;
The external force applied to the open / close cover is converted into the rotational torque of the fixing roller only when the cover is displaced in one of the directions from the shield position to the open position or from the open position to the shield position. And a transmission mechanism (in the case where the opening / closing cover is swingable, a torque transmitting mechanism for transmitting torque applied to the opening / closing cover to a rotating shaft). .

According to this configuration, torque can be transmitted to the fixing roller by opening and closing the cover. Therefore, a large torque for rotating the fixing roller can be obtained without using a manual dial. This eliminates the need for a space for providing a manual dial, and simplifies jam processing because the image forming apparatus does not have to be moved for jam processing. It is preferable that the transmission mechanism transmits an external force applied to the opening / closing cover to the fixing roller when the opening / closing cover is displaced from the shielding position to the opening position. In this case, since the torque is transmitted to the fixing roller by opening the opening / closing cover, the fixing roller can be rotated quickly, and the jam can be quickly cleared.

The fixing roller may include a pair of upper fixing roller and lower fixing roller, and the transmission mechanism may transmit torque to either the lower fixing roller or the upper fixing roller. , May be transmitted to both. Further, for example, the opening / closing cover is provided so as to be swingable, a fixing roller gear is connected to the fixing roller, and a supporting shaft gear is connected to a supporting shaft serving as a fulcrum of swinging movement of the opening / closing cover, respectively. The transmission mechanism may include one or more idle gears that connect the fixing roller gear and the spindle gear.

According to a second aspect of the present invention, the transmission mechanism comprises:
The image forming apparatus according to claim 1, further comprising a one-way clutch. According to this configuration, since a one-way clutch is used, torque transmission in only one direction can be performed without a special switching mechanism, so that the configuration is simple and no space is required. The one-way clutch is preferably interposed between the support shaft and the support gear.

According to a third aspect of the present invention, in the transmission mechanism, the external force applied to the open / close cover for displacing the open / close cover in the one direction is a direction corresponding to a conveying direction of the fixing roller. 3. The image forming apparatus according to claim 1, wherein the torque is transmitted to the fixing roller. According to this configuration,
By opening and closing the opening and closing cover, the jammed paper can be sent out and removed. This simplifies jam processing.

[0011]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an internal configuration of an image forming apparatus 1 according to an embodiment of the present invention. This image forming apparatus 1 has a black
Four image forming units 2B, 2M, 2C, and 2 for forming monochromatic images of magenta, cyan, and yellow, respectively.
Y has a so-called tandem type structure in which the sheets Y are arranged in a line in this order from the upstream side in the sheet conveying direction along a linear conveying path formed by the sheet conveying mechanism 3 for conveying the sheet P. .

Image forming units 2B, 2M, 2C, 2Y
Are provided with cylindrical photoconductors 4B, 4M, 4C, and 4Y, respectively, and are arranged in parallel with each other with their axes extending in a horizontal direction orthogonal to the paper transport direction.
The image forming units 2B, 2M, 2C, and 2Y
B, 4M, 4C, and 4Y, respectively, form black, magenta, cyan, and yellow single-color toner images. The toner images are guided to a position facing the paper transport mechanism 3 by rotation about the axis of the photoconductor. I will black,
The magenta, cyan, and yellow toner images are sequentially transferred onto the surface of the paper P while the paper transport mechanism 3 is transporting the paper P.

The paper transport mechanism 3 includes a drive roller 5 disposed further downstream than the most downstream image forming unit 2Y in the paper transport direction, and a further upstream from the most upstream image forming unit 2B in the paper transport direction. Roller 6, a driving roller 5 and a driven roller 6
Endless conveyor belt 7 wound around
And an auxiliary roller 8 for applying a tension to the sheet to suppress bending. With this configuration, when a driving force from a motor (not shown) is applied to the driving roller 5 to rotate the driving roller 5, the transport belt 7 rotates counterclockwise in FIG. The sheet P on which the toner image is to be transferred is transported linearly in the direction of arrow A by the rotation of the transport belt 7 while being carried on the upper surface of the transport belt 7.

At positions facing the photoconductors 4B, 4M, 4C, and 4Y from below, the upper portion of the conveyor belt 7 is sandwiched.
Transfer roller 9B for black, transfer roller 9 for magenta
M, cyan transfer roller 9C and yellow transfer roller 9Y are arranged. Each transfer roller 9B,
9M, 9C and 9Y press the conveyor belt 7 against the photoconductors 4B, 4M, 4C and 4Y from below, and transfer the toner images on the photoconductors 4B, 4M, 4C and 4Y to the paper P. It has a function.

Below the paper transport mechanism 3, a paper feed tray 10 capable of stacking and storing a plurality of papers P is disposed. The paper feed tray 10 includes a paper feed roller 12 for feeding the paper P from the paper feed tray 10 to the transport path 11 one by one. The paper P sent to the transport path 11 via the transport roller pair 13 by the rotation of the paper feed roller 12 is transported toward the registration roller pair 16 by the transport roller pairs 14 and 15. The registration roller pair 16 is connected to the paper transport mechanism 3 with respect to the transport direction of the paper P.
After stopping the transported paper P once, the image forming units 2B, 2M, 2C,
The sheet P is sent out onto the conveyor belt 7 in synchronization with the toner image forming operation in 2Y.

Each of the image forming units 2B, 2M, 2C, 2
Above Y, photoconductors 4B, 4M, 4C, 4Y
Laser scanning unit 17B, magenta laser scanning unit 17M, cyan laser scanning unit 17C, and yellow laser scanning unit 17Y for irradiating a laser beam to the laser beam.
Is arranged. The image forming apparatus 1 is connected to an external device (not shown) such as a microcomputer, for example. Image data input from this external device is
After being decomposed into color image data of each color component of black, magenta, cyan, and yellow, it is provided to laser scanning units 17B, 17M, 17C, and 17Y corresponding to each color.

The laser scanning units 17B, 17M, 17C, 1
7Y has a laser beam (not shown), a polygon mirror, a reflecting mirror, and the like. When color image data representing the densities of the respective colors of black, magenta, cyan, and yellow is input, based on the color image data, Modulated laser beams Lb, Lm, Lc, Ly
Are emitted toward the photoconductors 4B, 4M, 4C, and 4Y, respectively. The photoconductor 4B provided in the black image forming unit 2B is moved at a constant speed in the direction of the arrow (FIG. 1) during image formation.
(Clockwise direction in FIG. 3). Photoconductor 4B
A main charger 18, a developing device 19, and a cleaner 20 are arranged in this order along the rotation direction. The laser beam Lb incident from the black laser scanning unit 17B is applied to the surface of the photoconductor 4B between the main charger 18 and the developing device 19.

After the photoconductor 4B is uniformly charged by the discharge of the main charger 18, it is exposed to the laser beam Lb incident from the black laser scanning unit 17B. Thus, a so-called electrostatic latent image is formed on the surface of the photoconductor 4B. Photoconductor 4 on which electrostatic latent image is formed
Next, the surface of B is developed with black toner by the black developing device 19. When the photoconductor 4B is further rotated, the black toner image formed on the surface of the photoconductor 4B faces the paper transport mechanism 3.

On the other hand, the registration roller pair 16 is driven to rotate in synchronization with the toner image facing the paper transport mechanism 3, and the paper P is fed by the transport belt 7. A predetermined transfer voltage is applied to the black transfer roller 9B, which is disposed at a position facing the photoconductor 4B from below with the upper portion of the transport belt 7 interposed therebetween. Thus, the black toner on the surface of the photoconductor 4B is attracted to the black transfer roller 9B and is transferred to the upper surface of the sheet P. The toner remaining on the surface of the photoconductor 4B after the transfer of the toner image is collected by the cleaner 20.

The paper P on which the black toner image has been transferred in this manner is transported by the transport belt 7 to the image forming unit 2.
It is conveyed toward M, 2C, and 2Y. The image forming units 2M, 2C, and 2Y are configured similarly to the above-described black image forming unit 2B, and apply magenta, cyan, and yellow toner images to the photoconductors 4M, 4C, and 4Y in accordance with the conveyance timing of the paper P. Each of the single-color toner images formed thereon is sequentially transferred onto the paper P in an overlapping manner.

As described above, the paper P on which the toner images of the respective colors are transferred in an overlapping manner is separated from the transport belt 7 and
It is guided to the fixing unit 21. In the fixing unit 21,
A pair of fixing rollers 22 and 23 are provided. The upper roller of the pair of fixing rollers 22 and 23 is, for example, an upper fixing roller 22 as a heat roller for fusing toner adhering to the sheet P, and the lower roller is, for example, an upper fixing roller 22. Is a lower fixing roller 23 as a pressure roller which is pressed into contact with a predetermined pressure.

Thus, the sheet P conveyed toward the fixing unit 21 is sent out of the fixing unit 21 by the discharge roller pair 24 while being sandwiched between the upper fixing roller 22 and the lower fixing roller 23. At this time, the toner on the sheet P is melted by the upper fixing roller 22, and the melted toner is fixed on the sheet P by pressure. The sheet P after the fixing process is discharged to a discharge unit 2 by discharge roller pairs 25 and 26.
It is discharged to 7. FIG. 2 is a side view showing a state in which the discharge cover 31 of the fixing unit 21 is at an open position. The fixing unit 21 has a fixing upper roller 22 and a fixing lower roller 23 as a fixing roller in a housing 25 of the main body. However, in FIG. 2, the near side of the drawing is the front, and the far side of the drawing is the rear.

The upper fixing roller 22 has, for example, a cylindrical shape and extends in a horizontal direction perpendicular to the sheet conveying direction F, and has bearings (not shown) covering both ends. At the center of the upper fixing roller 22, a heater (not shown) is provided with both ends supported. The upper fixing roller 22 is rotatably held by opposing front and rear sides of the housing 25. An upper fixing roller gear 27 is connected to one end of the upper fixing roller 22. The upper fixing roller gear 27 is, for example, a motor (not shown) via a plurality of gears (not shown).
When the image forming apparatus 1 is operated, the motor is driven to rotate in the transport direction B. Accordingly, the upper fixing roller gear 27 also rotates in the transport direction B.

The lower fixing roller 23 has, for example, a cylindrical shape and extends in parallel with the upper fixing roller 22, and has bearings (not shown) covering both ends. Further, the fixing lower roller 23
A heater (not shown) is disposed at the center position of the battery with both ends supported. The lower fixing roller 23 is connected to the housing 2
5 is rotatably held by the opposed front and rear sides. The outer peripheral surfaces of the upper fixing roller 22 and the lower fixing roller 23 are in pressure contact with each other at a nip position 29. A lower fixing roller gear 30 is connected to one end of the lower fixing roller 23. When the image forming apparatus 1 is operating, the lower fixing roller 23
Is moved to the nip position 29 with the rotation of the upper fixing roller 22.
And rotates in the transport direction C by receiving the nip pressure. Accordingly, the lower fixing roller gear 30 also rotates in the transport direction C.

A side surface of the housing 25 on the downstream side with respect to the paper transport direction F is a discharge cover 31 as an opening / closing cover, and a support shaft 32 fitted to one edge thereof is rotated by the front and rear side surfaces of the housing 25. It is freely held.
As a result, the discharge cover 31 is moved between a shielding position that shields the inside and the outside of the housing 25 and an open position that opens the inside of the housing 25 to the outside as shown in FIG.
It is mounted swingably. At one end of the support shaft 32,
A spindle gear 34 is connected via a one-way clutch 33. The one-way clutch 33 includes the discharge cover 31.
When the shaft is opened, that is, when the support shaft 32 rotates in the direction of arrow D, the torque of the support shaft 32 is transmitted to the support shaft gear 34, but when the discharge cover 31 is closed, that is, when the support shaft 32 is , The torque of the support shaft 32 is not transmitted to the support shaft gear 34. A discharge roller pair 24 is rotatably attached to the discharge cover 31.

The lower fixing roller gear 30 and the support shaft gear 34 can transmit torque through an idle gear 35. A rotary shaft 36 is fitted into the idle gear 35, and the rotary shaft 36 is rotatably held by the front and rear sides of the housing 25. When the spindle gear 34 is rotated in the direction of arrow D, the idle gear 35
Is rotated in the direction of arrow E, and the lower fixing roller gear 30 and the lower fixing roller 23 are rotated in the transport direction C.

In the present embodiment, the support shaft 32, the one-way clutch 33, the support shaft gear 34, the idle gear 35, and the lower fixing roller gear 30 form a transmission mechanism (torque transmission mechanism). The one-way clutch 33 is not limited to the position between the support shaft 32 and the support shaft gear 34, and may be provided, for example, between the idle gear 35 and its rotation shaft 36, or may be provided between the lower fixing roller gear 30 and the lower fixing roller 23. May be provided between them.

Further, the upper fixing roller gear 27 and the lower fixing roller gear 30 may be meshed with each other. In this case, the lower fixing roller gear 30 is rotated by the driving of the motor, and the spindle gear 34 is also rotated accordingly. However, the one-way clutch 33 idles and does not transmit torque to the spindle 32. Therefore, the one-way clutch 33 does not transmit the torque when the image forming apparatus 1 is operating, but transmits the torque when the discharge cover 31 is opened, so that the upper fixing roller 22 and the lower fixing roller 23 are integrally moved in the conveying direction B, Rotated to C.

The one-way clutch 33 is not limited to the position between the lower fixing roller 23 and the support shaft 32 of the discharge cover 31, but may be provided between the upper fixing roller 22 and the support shaft 32 of the discharge cover 31. Good. FIG. 3 shows the fixing unit 21.
FIG. 6 is a schematic view showing an operation mode of the jam release mechanism of FIG. FIG.
FIG. 3A is a schematic diagram illustrating a state in which the discharge cover 31 of the fixing unit 21 is in the shielding position, and FIG. 3B is a schematic diagram illustrating a state in which the discharge cover 31 of the fixing unit 21 is in the open position. is there.

When the discharge cover 31 is displaced in the opening direction from the shielding position shown in FIG. 3A, the torque of the support shaft 32 is transmitted to the support shaft gear 34 via the one-way clutch 33, and the support gear 34 Rotates in the direction of arrow D. Accordingly, the idle gear 35 rotates in the direction of arrow E, and the lower fixing roller gear 30 and the lower fixing roller 23 rotate in the transport direction C. The upper fixing roller 22 receives the nip pressure at the nip position 29 and rotates in the transport direction B. The sheet P having the leading end in contact with the nip position 29 is sent out by the upper fixing roller 22 and the lower fixing roller 23 to be in a state as shown in FIG.

When the discharge cover 31 is displaced in the shielding direction from the open position shown in FIG. 3B, the one-way clutch 33 idles, and the torque of the support shaft 32 is not transmitted to the support shaft gear 34. Therefore, the position of the sheet P is as shown in FIG.
The discharge cover 31 returns to the shielding position shown in FIG. By repeatedly displacing the discharge cover 31 between the shielding position and the open position as needed, the leading end of the paper P is gradually fed out, and the paper P is pulled out to perform the jam processing.

The present invention is not limited to the contents of the above embodiments, and various changes can be made within the scope of the claims. For example, the torque transmission mechanism is not limited to the one based on the connection of a plurality of gears, and may include a belt such as a timing belt. In addition, the idle gear 35 is not limited to one, and a plurality of idle gears may be provided or may not be provided. One-way clutch 3
3 is provided between the lower fixing roller 23 and the support shaft 32 of the discharge cover 31, when the number of idle gears 35 is odd, when the discharge cover 31 is opened, and when the number of idle gears 35 is even, When the ejection cover 31 is closed, the paper P is sent out. When the one-way clutch 33 is provided between the upper fixing roller 22 and the support shaft 32 of the discharge cover 31, when the idle gear 35 is an odd number,
If the number of idle gears 35 is even when the discharge cover 31 is closed, the paper P is sent out when the discharge cover 31 is opened. If the number of idle gears 35 is set so that the paper P is sent out when the discharge cover 31 is opened, the paper P is sent out when the discharge cover 31 is first opened in the initial state where the discharge cover 31 is closed. Therefore, the efficiency is higher than when the sheet P is sent out by closing the discharge cover 31.

The shaft gear 34 is not limited to a circular cross section, but may have a sector shape, for example.
In this case, the radius of the spindle gear 34 can be increased. Therefore, the ratio of the sheet P sent out with respect to the constant displacement amount of the discharge cover 31 increases, so that the efficiency is high. Further, the number of idle gears 35 can be reduced, and in some cases, the idle gears 35 can be omitted. However, in the case of using the spindle gear 34 having a fan-shaped cross section, if the one-way clutch 33 is provided between the spindle 32 and the spindle gear 34, the opening and closing of the discharge cover 31 is repeated, so that the spindle gear 34 gradually becomes It rotates and comes off the idle gear 35. Therefore, when the one-way clutch is provided between the lower fixing roller 23 and the support shaft 32 of the discharge cover 31, the idle gear 35 and its rotating shaft 36,
Alternatively, a one-way clutch may be provided between the lower fixing roller 23 and the lower fixing roller gear 30. The one-way clutch is connected to the fixing upper roller 22 and the support shaft 32 of the discharge cover 31.
To be provided between the idle gear 35 and the rotating shaft 36 thereof, or the upper fixing roller 22 and the upper fixing roller gear 2.
7, a one-way clutch may be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an internal configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a side view showing a state in which a discharge cover of a fixing unit is at an open position.

FIG. 3 is a schematic view illustrating an operation mode of a jam release mechanism of the fixing unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Upper fixing roller 23 Lower fixing roller 31 Discharge cover 33 One-way clutch P Paper

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2C058 AB16 AC08 AD04 AF15 AF54 AF61 GB14 GB22 GE15 2H033 AA37 BA06 BA10 BA12 BB37 2H072 AA02 AA16 AA22 AB20 EA15 EA16

Claims (3)

[Claims] A fixing roller for fixing and conveying the toner image transferred onto the sheet; a shielding position for shielding the fixing roller from the outside; and an open position for opening the fixing roller to the outside. The displaceable opening / closing cover, and the external force applied to the opening / closing cover is only applied when the opening / closing cover is displaced from the shielding position to the opening position or from the opening position to the shielding position in one of the directions. A transmission mechanism that converts the torque into a rotational torque of a fixing roller and transmits the torque. 2. The image forming apparatus according to claim 1, wherein said transmission mechanism includes a one-way clutch. 3. The transmission mechanism transmits an external force applied to the opening and closing cover to displace the opening and closing cover in the one direction to the fixing roller as a torque in a direction corresponding to a conveying direction of the fixing roller. The image forming apparatus according to claim 1, wherein the image forming apparatus performs the operation.