JPH04316076A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device for improving positional precision with respect to the fixing roller of a separating pawl and preventing the fixing roller from being scratched by the separating pawl. CONSTITUTION:The shaft 9 of the rear part of a paper ejecting upper guiding plate 14 having the separating pawl 3 is supplied into the round oblong hole 20 of a paper electing side plate 6 freely turning centering a fulcrum 5. Further, the shaft 8 of the front part is pressed by a spring 12 so as to be engaged with the notch 18 of a fixing side plate 7 at the time of the abutting of the separating pawl 3, and a notch formed more deeply than the notch 18 on the paper electing upper guide 10 at the time of separating.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image forming apparatuses such as copying machines and laser beam printers.

0002

[Prior Art] Conventionally, an image forming apparatus used in copying machines, laser beam printers, facsimile machines, etc. is shown in FIG.
A configuration as shown in is known. In this device, a controller (not shown) first sends a signal to the laser oscillator 40 to generate laser light. Next, this light is reflected by a rotating mirror 41 (generally called a polygon mirror), and is further turned back by a reflecting mirror 42 to irradiate the photosensitive drum 43 with laser light. In this way, by controlling the laser oscillator 40 with the controller and further rotating the photosensitive drum 43, a so-called latent image is formed on the photosensitive drum 43. The latent image on the photosensitive drum 43 is developed as a toner image by a developing device 44, and then transferred onto a sheet of paper 45.

The paper 45 is fed one by one from a cassette 47 by a pip-up roller 46, and the above-described transfer is performed when the paper 45 passes under the photosensitive drum 43. Thereafter, the paper 45 is guided to a pair of fixing rollers 48 and 49 and pressed against the pair of rollers, and at the same time is heated by a heater within the rollers to fix the toner image on the paper 45. The paper 45 with the toner image fixed thereon is discharged by a pair of paper discharge rollers 1 and 2 onto a paper discharge tray 50 provided outside the main body of the apparatus, thereby completing the image forming process.

[0004] In such an image forming apparatus, when a so-called jam occurs due to paper jamming during the image forming process, an operation (jam processing) is performed to remove the jammed paper from the apparatus main body. Therefore, it is necessary to make the paper passage path openable and closable. For example, as for the configuration of the fixing section and the paper ejection section, the one shown in FIG. 7 is well known in consideration of such jam handling properties.

In FIG. 7, a paper discharge upper guide plate 10, a paper discharge lower guide plate 11, which are holding members for the separation claws 3, 4, and a paper discharge roller pair 1, 2 are all attached to a paper discharge side plate 6, which is a rotating member. There is. Also, a pair of fixing rollers 48 that press the paper,
An upper separating claw 3 and a lower separating claw 4 for separating the paper from the paper 49 are attached to the upper paper discharge guide plate 10 and the lower paper discharge guide plate 11, respectively, and the separating claws 3 and 4 are provided with The fixing roller 48 is pressed against the fixing roller 48 by a spring 13 in the direction of rotation about an axis. Further, a hook 14 is provided on the paper discharge side plate 6, and this hook 14 is configured to engage with a protrusion 15 of the main body of the image forming apparatus.

In such an apparatus, if the paper jams in the fixing section and the paper ejecting section, the user operates the hook 14 in the direction shown by arrow a in the figure and removes the hook 1.
4 from the protrusion 15 of the main body. The paper ejection section is the paper ejection side plate 6.
Since it is rotatable around the upper paper discharge fulcrum 5, it is rotated as shown by arrow A in the figure. As a result, the fixing section and the paper ejection section are separated, so that it is possible to remove paper jammed in this peripheral area.

[0007]

[Problems to be Solved by the Invention] However, the above conventional example has the following problems. (1) First, there was a problem in that since the separation claw was brought into contact with the fixing roller, the fixing roller would be scratched. When such scratches occur on the fixing roller, the releasability of the toner in that area decreases, so when the paper to which the toner image has been transferred is pressed between the pair of fixing rollers 48 and 49, the image on the paper may be damaged. Sometimes it would come out in white streaks.

[0008] There are two possible causes for the above-mentioned damage caused by the separation claw to the fixing roller. One type of damage is caused simply by the separation claw contacting the fixing roller and the fixing roller rotating. This largely depends on static conditions such as the contact pressure of the separating claw against the fixing roller by the tension spring 13, the materials of the separating claw and the fixing roller, and the contact angle of the separating claw. The other problem is scratches that occur during the process of setting the separation claw on the fixing roller. As mentioned earlier, the paper ejection section including the separation claw is separated from the fixing device in order to clear the paper jam, but after the paper jam clearing is completed, the paper ejection section is returned to the set state. edge,
The trajectory of the separation claw 3 is as shown in FIG. Separation claw 3
The fixing roller 49 is configured to generate a predetermined contact pressure when set against the fixing roller 49.
When the object is separated from the object, it rotates a certain angle and stops. That is, the state is B in the figure.

Next, when the paper ejecting section is rotated around the fulcrum 5, the tip of the separation claw 3 first comes into contact with the fixing roller 49 (state G), and then the setting is completed (state H). The tip of the separating claw 3 slides on the fixing roller 49 over the length of the arc l. Further, in this process, the contact angle of the separation claw 3 begins to contact the fixing roller at an angle β that is larger than the angle in the set state, so that the separation claw 3 moves in a state of gouging the surface of the fixing roller. For this reason, the separation claw 3 is damaged in the range of the arc 1.

Regarding the occurrence of scratches on the separating claws due to the first static condition mentioned above, it is possible to appropriately set the contact pressure of the separating claws and to ensure that the position of contact of the separating claws with respect to the roller is accurate. It has been difficult to reduce the occurrence of scratches due to the gouge of the second separation claw since the paper ejection section is configured as in the conventional example. (2) Next, as mentioned above, the positional accuracy of the separating claw with respect to the fixing roller is the main factor that affects the occurrence of scratches on the separating claw with respect to the fixing roller. It also greatly affects the separation performance of separating paper.

In other words, if the separating claw is not arranged with a predetermined precision with respect to the fixing roller, the contact angle and contact pressure of the separating claw with respect to the fixing roller will be deviated, and there is a possibility that the paper will not be separated from the roller. Yes, this can cause paper jams.

However, in the case of using the conventional paper ejecting section configuration, the positional accuracy of the separating claw with respect to the fixing roller is limited by the side plate 7 of the fixing device, the main body of the image forming apparatus, the protrusion 15 and the hook 14.
, the combination of the hook 14 and the paper ejection side plate 6, the paper ejection side plate 6 and the paper ejection upper guide plate 10, and the paper ejection upper guide plate 10 and the separation claw 3. It has been difficult to improve the accuracy of the fixing roller.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, improve the positional accuracy of the separating claw with respect to the fixing roller, and provide an image forming apparatus in which the fixing roller is not damaged by the separating claw. .

[0014]

[Means for Solving the Problems] According to the present invention, the above object is achieved by providing a fixing roller and a pressure roller that are arranged in pressure contact with each other, and a surface of at least one of the fixing roller and the pressure roller. Separation claws arranged so as to be in contact with each other, a holding member for the separation claws, and a rotation member arranged rotatably to engage with the holding member to cause the separation claws to separate from and come into contact with the surface. An image forming apparatus including a moving member,
The rear part of the holding member is engaged with the rotating member such that the front part holding the separating claw rotates relative to the rotating member, and the holding member is in contact with the separating claw. Sometimes, the front portion is engaged with supporting members of the fixing roller and the pressure roller to determine the position, and when the separating claw is separated, the front portion is in pressure contact between the fixing roller and the pressure roller at a position lower than the position at the time of contact. This is achieved by engaging with the rotating member at a position rotated toward the front side.

[0015]

According to the present invention, the front portion of the holding member is engaged with the support members of the fixing roller and the pressure roller when the separating claws are in contact with each other. When the rotating member is rotated in the opening direction from this state to separate the separating claws, the front portion rotates at a position closer to the pressure contact portion of the fixing roller and the pressure roller than the position at the time of contact. It engages with the member and becomes tilted relative to the rotating member. Thereafter, when the rotating member is rotated in the closing direction in order to bring the separating claw into contact again, the front portion engages with the supporting member during the rotation and is positioned. However, at this point, the holding member is in an inclined state, so the separation claws are not in contact with it. Since the engaging position of the rotating member and the front portion is close to the pressure contact portion, the rotating member continues to rotate after this point with the front portion engaging only with the supporting member. Therefore, the holding member rotates with respect to the rotating member so as to correct the above-mentioned relative inclination, and the separation claw also rotates accordingly to perform the abutting operation against the fixing roller or the pressure roller.

[0016]

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention. Reference numeral 6 shown by a two-dot chain line in FIG. 1 is a side plate of the paper discharge section, which is a rotating member, and is engaged with a paper discharge upper guide plate 10, which is a holding member of the separation claw 3. The paper discharge upper guide plate 10
are provided with shafts 8 and 9, which are rotatable relative to the side plate 6. Further, the separation claw 3 has its shaft dropped into an arcuate recess provided in the paper discharge upper guide plate 10, and the tension spring 13 rotates around the shaft.
The fixing roller 49 is brought into contact with the fixing roller 49 by the fixing roller 49 . Further, the paper ejection upper guide plate 10 has a notch 17 into which the tip of the separation claw 3 is inserted, so that when the paper ejection section is rotated and released from the fixing side plate 7 which is a supporting member of the fixing roller 49, the paper is separated. The claw 3 is rotated by a tension spring 13 and remains stationary with the separation claw 3 in contact with the notch 17. This is similar to the configuration described in the conventional example, and is shown in FIG.
It becomes the state of G.

Further, the paper discharge side plate 6 has a notch 19, and the fixing side plate 7 has a notch 18. Further, the shaft 9 provided on the paper discharge upper guide plate 10 is movable by penetrating the round elongated hole 20 on the paper discharge side plate 6.

On the other hand, a tension spring 12 is hung diagonally on another shaft 8 provided on the paper discharge upper guide plate 10, and the other end of the spring is fixed on the paper discharge side plate 6. Therefore, the shaft 8 can be engaged with either of the notches 18 and 19.

In the above-described apparatus, let us first consider the state in which the paper discharge section is rotated and released from the fixing device and then set again on the fixing device side. In FIG. 2, the paper ejection section is shown rotating toward the fixing device from an open state. At this time, the paper discharge upper guide plate 10 is the paper discharge upper guide plate 1.
The tensile force of the spring 12 applied to the shaft 8 provided on the shaft 8 creates the state shown in the figure. That is, the shaft 9 of the paper discharge upper guide plate 10 is pulled toward the fixing device side in the round elongated hole 20 of the paper discharge side plate 6, and the shaft 8 is also pulled toward the fixing device side in the notch 19 of the paper discharge side plate 6. It is pulled toward the fixing device side, and the notch 1
It hits the front part of 9. In other words, the paper discharge upper guide plate 1
0 is pulled in the direction of arrow x by a spring 12 so that the shaft 8 butts in the notch 19. At this time, the front part of the paper discharge upper guide plate 10 provided with the separation claw 3 is tilted with respect to the paper discharge side plate 6, with the front part being lowered in the direction of the arrow x. This is because the cutout 19 of the paper discharge side plate 6 is located lower than the cutout 18 of the fixing side plate 7 when the paper discharge section is set as shown in FIG.

Next, when the paper discharge section is further rotated toward the fixing device side, the state shown in FIG. 3 is obtained. As shown in FIG. 1, the shaft 8 provided on the paper ejection upper guide plate 10 extends outward from the fixing side plate 7, so when the paper ejection section is rotated to a certain point, as shown in FIG. The shaft 8 is the fixing side plate 7
It abuts against the horizontal portion of the notch 18 provided above. Since the fixing side plate 7 remains fixed, if the paper ejection side plate 6 is pushed in further than the state shown in the figure, the shaft 8 will advance to the corner of the notch 18 of the fixing side plate 7 as shown in FIG. receive.

Further, with the closing operation of the paper discharge section as described above, the front part of the paper discharge upper guide plate 10 rotates upward relative to the paper discharge side plate 6 from the position shown in FIG. . this is,
As described above, the notch 18 of the fixing side plate 7 is located higher than the notch 19 of the paper ejection side plate 6, and the shaft 8 is moved during the transition from the state shown in FIG. 3 to the state shown in FIG. This is because the paper discharge side plate 6 is rotated while being in contact with the notch 18. Therefore, the tip of the separation claw 3 provided at the front of the paper discharge upper guide plate 10 also rotates in the direction of contacting the surface of the fixing roller 49 during the transition from the state shown in FIG. 3 to the state shown in FIG. Become. Furthermore, since the length of the horizontal portion of the notch 19 is longer than that of the notch 18, the engagement between the shaft 8 and the notch 19 occurs during the transition from FIG. 3 to FIG. There is a state in which the blade comes off and completely contacts only the notch 18. At this time, the shaft 9 is also moved to the left side of the round elongated hole 20. In other words, in a state where the shaft 8 is in contact with only the notch 18, the paper ejection upper guide plate 10 is positioned in the forward direction with respect to the surface of the fixing roller 49, and from that state onwards, as shown in FIG.
Until the state is reached, the paper discharge upper guide plate 1 described above
The separation claw 3 is brought into contact only by the relative rotation of the separation claw 3.

By adopting such a configuration, first of all, the positional accuracy of the separating claw 3 with respect to the fixing roller 49 is determined by the extremely simple component configuration of the fixing device, the upper paper ejection guide plate 10, and the separating claw 3. Therefore, the positional accuracy of the separating claw 3 with respect to the fixing roller 49 can be easily guaranteed. Therefore, it is easy to prevent the separation of the paper from the fixing roller 49 by the separation claw 3, that is, the occurrence of a jam. Furthermore, the occurrence of scratches on the surface of the fixing roller due to the static conditions described in the conventional example is suppressed.

Second, the separation claw 3 is prevented from being gouged against the fixing roller 49 when the paper discharge section is set in the fixing device. Specifically, with regard to each of FIGS. 2 to 4 described above, the trajectory of the state of the separation claw 3 in the illustrated state will be traced. Figure 5 shows the trajectory. ■,■ in the figure
, ■ indicate the positions of the separation claws in FIGS. 2, 3, and 4, respectively. The rough trajectory of the separation claw 3 moves as indicated by arrows J and K.

That is, the separating claw 3 approaches the surface of the fixing roller 49 by the rotation of the paper discharge side plate 6 in the J direction from ■ to ■, and then approaches the surface of the fixing roller 49 by the relative rotation of the paper discharge upper guide plate 10. It comes into contact with the above surface while rotating in the K direction. In addition, between ■ and ■, the shaft 8 comes into contact with only the notch 18 as described above, so positioning in the forward direction is performed at that point, and from then on, only rotation in the K direction is performed. The contact operation is performed by. Therefore, unlike the conventional example, the tip of the separating claw 3 is connected to the fixing roller 4.
9 is not gouged over the length of the arc 1, and no scratches are generated on the surface.

[0026]

[Effects of the Invention] As explained above, according to the present invention,
The holding member of the separating claw is rotatable relative to the rotating member, and the front part of the holding member having the separating claw is positioned with respect to the supporting member of the fixing roller and the pressure roller when the separating claw is in contact with the holding member. When separating the separating claw, the rotating member is placed at a position closer to the pressure contact portion of the fixing roller and the pressure roller at the time of contact than the position with the support member, so that The positional accuracy of the separation claw can be guaranteed. Therefore, occurrence of jam can be prevented. In addition, when the paper ejection section is closed after handling a jam, no scratches are caused by the separating claw on the surface of the fixing roller or the pressure roller, and a good image can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of a device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which the rotating member of the apparatus shown in FIG. 1 is rotated and released from the supporting member of the fixing roller and the pressure roller.

FIG. 3 is a diagram showing a state immediately before the front part of the holding member of the separation claw of the apparatus shown in FIG. 1 engages with the supporting members of the fixing roller and the pressure roller.

4 is a diagram showing a state in which the separating claw of the device shown in FIG. 1 is brought into contact with a fixing roller and a pressure roller; FIG.

FIG. 5 is a diagram showing the moving state of the separation claw from FIGS. 2 to 4;

FIG. 6 is a sectional view showing a schematic configuration of a conventional image forming apparatus.

7 is a diagram illustrating the approaching and separating operations of the separating claw in the device shown in FIG. 6; FIG.

8 is a diagram showing a moving state of the separation claw in FIG. 7. FIG.

[Explanation of symbols]

3, 4 Separation claw 6 Rotating member (paper discharge side plate) 7 Support member (fixing side plate) 10, 11 Holding member (paper discharge upper guide plate, paper discharge lower guide plate) 48 Fixing roller 49 Pressure roller

Claims (1)

[Claims] 1. A fixing roller and a pressure roller disposed in pressure contact with each other, a separating claw disposed in contact with a surface of at least either the fixing roller or the pressure roller, and the separating In an image forming apparatus, the image forming apparatus includes a holding member for a claw, and a rotating member that is rotatably arranged and engages with the holding member to cause the separating claw to move away from and come into contact with the surface, wherein the holding member The rear part of the is engaged with the rotating member such that the front part holding the separating claw rotates relative to the rotating member, and the holding member is configured to rotate when the separating claw comes into contact with the rotating member. The front portion is positioned by engaging with the supporting member of the fixing roller and the pressure roller, and when the separating claw is separated, the front portion is closer to the pressure contact portion of the fixing roller and the pressure roller than the position when the separation claw is in contact with the fixing roller. An image forming apparatus that engages with the rotating member at a rotated position.