JPH0812526B2 - Roller pressure contact mechanism of image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure contact mechanism of a pressure roller used in a transfer device or a fixing device of an image forming apparatus such as a copying machine or a printer.

[Prior art]

Generally, in image forming apparatuses such as copiers and printers,
In a transfer device that transfers a toner image on an image carrier to a transfer paper by pressure, a device that fixes the toner image on the transfer paper at the same time, or a fixing device that fixes an unfixed toner image on the recording paper by heat or pressure, a pressure roller A pressure contact mechanism is used to contact the image carrier with the image carrier or the fixing roller.

As an example of such a roller pressure contact mechanism, one having a structure as shown in FIG. 7 is known (Jitsuko Sho 57-34517).
issue). That is, the shaft 42 of one roller 41 is supported by the holding body 43, the arm 44 is pivotally attached to one end of the holding body 43 by the engagement shaft 45, and the shaft 47 of the other roller 46 is attached to this arm 44. Both rollers 41, 46 are axially supported so that they face each other, and
Loosely insert the bolt 48 into the other end of 3 and the other end of the arm 44, tighten with the nut 50 via the coil spring 49, and
The 6 is configured to be in pressure contact with a predetermined pressure.

[Problems to be solved by the invention]

Generally, in a roller pressure contact mechanism of an image forming apparatus, the pressure roller is released from pressure contact for removal or reattachment in order to remove jammed paper when recording paper is jammed or for maintenance. Operation is required.

However, the conventional roller pressure contact mechanism as shown in FIG. 7 has a drawback that it is extremely difficult to attach / detach the pressure roller, particularly to attach it. That is, in order to extract the pressure roller 46 in the axial direction, first, the arm 44
However, it is extremely difficult to remove it because it is connected to the holding body 43 by the engagement shaft 45.
In addition, an extremely strong coil spring is used between the rollers to apply a pressure contact force of, for example, 30 kg / cm, a special tool is required to install this, and the pressure contact force due to the tightening amount of the bolt is also used. However, since the compression length of the coil spring is long, the pressure source becomes large and it is difficult to save space in the device.

In addition, in order to avoid increasing the size of the pressure source etc., the spring that generates the pressure contact force of the pressure roller is compressed and maintained in advance to some extent, and a small amount of displacement is added to the spring by a separately provided cam to obtain the desired spring force. The roller pressing mechanism configured to obtain the above is also disclosed in JP-A-57-92360 and JP-A-56-109382.

However, in the roller pressure contact mechanism disclosed in these publications, since the spring force of the spring is always applied to the adjusting member for adjusting the pressure contact force of the roller, it is difficult to adjust the pressure contact force by the adjusting member, There is a problem that the reproducibility of the pressure contact force is poor when the pressure roller is reattached.

The present invention has been made to solve such a problem in the conventional roller pressure contact mechanism, can save space in the apparatus, and can easily adjust the pressure contact force of the roller pressure contact mechanism of the image forming apparatus. It is intended to be provided.

[Means and Actions for Solving Problems]

In order to solve the above problems, the roller pressing mechanism of the image forming apparatus of the present invention is a roller pressing mechanism of the image forming apparatus for pressing a pair of rollers for nipping and conveying a sheet, and one roller is directed to the other roller. A pressing member that presses the spring member through a spring member, and a displacement unit that displaces the pressing member between a first position that presses the spring member and a second position that is retracted from the first position, A spring restricting member that receives the spring force of the spring member instead of the pressing member during the displacement of the pressing member from the first position to the second position; and the spring restricting member, which is provided in the pressing member, When receiving the spring force of the spring member,
And an adjusting member for adjusting the amount of pressing of the spring member by the pressing member.

The operation of this structure will be described with reference to FIG.

8A and 8B conceptually show the roller pressure contact mechanism of the present invention. FIG. 8A is a state where the roller is in pressure contact, FIG. 8B is a state where the pressure contact is released, and FIG. 8C is a roller. It shows how the pressure contact force is adjusted.

As shown in FIG. 8A, when the rollers are pressed against each other, the displacement means 51 including a cam displaces the pressing member 52 upward against the spring force of the spring member 54, so that the pressing member 52 springs. The pressure roller 55 is pressed against the pressure roller 56 via the member 54. The position of the pressing member at this time is the first position described above.
Position.

On the contrary, when releasing the pressure contact of the roller pair, the displacing means 51 displaces the pressing member 52 downward from the state shown in FIG. 8A as shown in FIG. 8B. The spring force of the spring member 54 acts on the pressing member 52 until the middle of this downward displacement, but when the spring extends until the lower end of the spring member 54 contacts the spring restricting member 53, it is applied to the pressing member 52. The existing spring force is applied to the spring restraint member 53, and the pressing member 52 is released from the spring force. The position of the pressing member at this time is the above-mentioned second position.

Then, if the amount of protrusion of the adjusting member 52a is changed as shown in FIG. 8 (C) when the spring force of the spring member is applied to the spring regulating member, the pressing member is released in the state of being released from the spring force. When displaced to the first position shown in FIG. 8 (A),
The pressing amount of the spring member 54 by the pressing member 52 can be adjusted.

〔Example〕

Examples of the present invention will be described below. Figure 1
It is a schematic perspective view which shows one Example of the roller pressure contact mechanism which concerns on this invention. This embodiment shows a mechanism for pressing and separating the pressure roller from the pressure roller, and in the figure, only one side of the mechanism, that is, the front side is shown.
Although the other back side is omitted, it has a mechanism similar to this. In the figure, reference numeral 1 denotes a pressure roller, which corresponds to a fixing roller in a fixing device and an image carrier such as a photosensitive drum or a dielectric drum in a transfer device, and is provided on a side plate (not shown) of the mechanism main body. It is rotatably attached via the shaft 2. Reference numeral 3 denotes a pressure roller, and a shaft 4 of the roller 3 is dropped into a U-shaped notch bearing portion 6 provided at a substantially central portion of an arm 5 whose one end is rotatably supported so as to be rotatable. It is supported.
At one end of the arm 5, there is a U facing in the opposite direction to the U-shaped bearing portion 6.
A U-shaped support portion 7 is formed, and the U-shaped support portion 7 is engaged with a pivot shaft 8 fixed to a side plate of the mechanism body to rotatably support the arm 5.

At the other end of the arm 5, as shown in FIG.
A through hole 9 is formed so that the through hole 9 can be loosely inserted, and a tie bar 11 is arranged above the arm 5 so as to intersect with the portion where the through hole 9 is provided. And tie bar
A bolt through hole 12 is formed in the portion of the arm 11 facing the through hole 9 provided in the arm 5, and a bolt 10 is inserted from the bolt through hole 12 to pass through the through hole 9 of the arm 5.
Furthermore, a preload package placed on the lower end surface of the arm 5.
After inserting it through the through hole portion of 13, the knob 14 is screwed to the lower end of the bolt 10 so that the tie bar 11, the arm 5 and the preload package 13 are integrally connected by the loosely inserted bolt 10. Is configured.

One end of a bar 15 is further attached to the pivot shaft 8, and the bar 15 is arranged in parallel with the arm 5 so that the upper surface of the other end engages with the lower surface of one end of the tie bar 11. ing. A cam surface of a cam 17, which is a displacement means attached to one end of a cam shaft 16 which is also supported by the mechanism side plate, is slidably engaged with the lower surface of the other end of the bar 15. Reference numeral 18 is a handle fixed to the cam shaft 16.

Next, the preload package will be described. A preload package is a pressure spring unit with a preload mechanism, which has a predetermined compression spring pressure (for example, 200 k
In order to obtain g), when it is necessary to compress the spring by a predetermined distance (for example, 10 mm), a unit that can hold the spring compressed by a distance close to the predetermined distance (for example, 9 mm) is formed in advance. During the pressurizing operation, a predetermined compression spring force (for example, 200 kg) can be generated by compressing a short distance (for example, 1 mm).

In this embodiment, it is constructed as shown in FIG. That is, the pressure spring 13 _-1 is housed in the bottomed cylindrical preload frame 13 _-2 , and the frame 13 _-2 together with the knob 14 is provided so that the bottom surface of the frame 13 _-2 can contact the lower surface of the arm 5. It is loosely inserted into the lower end of the bolt 10 that constitutes the pressing member. Then, a cylindrical lid 13 _-3 as a spring regulating member is inserted fixed to the open end of the pre-load frame 13 _-2 preset a free end of the pressure spring 13 _-1 through a pressing ring 13 _-4 In addition, the compression force, for example, a pressure of 9 kg and a compression force of 180 kg is pressed and held.

Further, a knob 14 as an adjusting member is fixed to the lower end of the bolt 10, the upper end portion of which is inserted into the cylindrical lid 13 _-3 , and the end surface of which can abut the pressing ring 13 _-4. It has become.

The state shown in FIG. 2 is the head of the bolt 10.
10 'underside is raised bolt 10 in contact with the upper surface of the tie bar 11, pressed against the ring 13 _-4 pressing knob 14 provided at its lower end, the end surface of the presser ring 13 _-4 lid 13 _-3 More slightly, for example, by pushing about 1 mm, the pressure spring 13 _-1 is further compressed than the initially set compression state, and the pressure arm 5 is pressurized with a predetermined pressure via the preload frame 13 _-2 . The pressure roller 3 is pressed against the pressure roller 1 at a predetermined pressure.

Next, the operation of the roller pressing mechanism constructed as described above will be described. When pressure is applied to the pressure roller 3 and brought into pressure contact with the pressure roller 1 to bring it into an operating state, first, the handle 18 provided on the cam shaft 16 is rotated in the direction of the arrow (in FIG. 1, the handle is rotated). When the cam 17 has finished moving), the cam 17 slides on the lower end surface of the bar 15 to be in a pressurizing operation state, and pushes one end of the bar 15 upward. By the pushing-up operation of the bar 15, the tie bar 11 engaged with the upper surface of the bar 15 is pushed up, thereby pulling up the bolt 10 mounted on the tie bar 11. By this pull-up operation of the bolt 10, the knob 14 pulls up the holding ring 13 _-4 of the preload unit 13 and compresses the pressure spring 13 _-1 by a predetermined amount to generate a predetermined spring pressure, and the preload frame 13 _-2.
The upper surface of pushes up the arm 5. As a result, the arm 5 rotates about the support portion 7 with the pivot shaft 8 as a fulcrum and pushes up the pressure roller shaft 4, so that the pressure roller 3 can be pressed against the pressure roller 1 with a predetermined pressing force.

Next, when the pressure roller 3 is removed from the pressure contacting state of the pressure roller 3 for removing jammed paper or for maintenance, the following operation is performed. First, when the handle 18 is rotated in the direction opposite to the arrow to release the pressurization operation state of the cam 17 to the bar 15, the pressure applied to the preload package 13 via the bar 15, the tie bar 11, and the bolt 10 is released. It will be canceled. When the pressure applied to the preload package 13 is released, the pressing ring 13 _-4 comes into contact with the end surface of the lid 13 _-3 and the spring force is not applied to the knob 14, so
The knob 14 can be easily rotated with a finger or the like.
By removing 14 from the bolt 10, the preload package 13 can also be easily removed from the bolt 10.
At this time, since the pressure spring 13 _-1 is housed in the preload frame 13 _-2 , the constituent members of the preload package 13 do not come apart and the preload package 13 can be handled as a single unit.

Next, when the arm 5 is moved slightly downward, the pressure roller shaft 4 is disengaged from the U-shaped bearing portion 6 of the arm 5, so that the pressure roller 3 can be pulled out in the axial direction. At this time, since one end of the arm 5 is configured such that the U-shaped support portion 7 can be attached to and detached from the pivot shaft 8, the arm 5 can be detached from the pivot shaft 8, thereby making it easier to press the pressure roller. 3 can be removed. In addition, the removal work of the preload package 13 is not performed for those arranged on the back side,
You only have to do this for the ones that are located on the front side.

Next, a procedure for reattaching the removed pressure roller will be described. During maintenance, as described above, the pressure contact mechanism of the pressure roller on the back side is not disassembled at all, so there is no need to reassemble it.
When the pressure contact mechanism on the back side is disassembled, the arms, tie bars, bolts, preload packages, bars and the like arranged on the back side are assembled in a predetermined arrangement configuration in advance. Next, the pressure roller 3 is inserted into the mechanism from the front side, and one end of the pressure roller shaft 4 is engaged with the U-shaped bearing portion of the arm arranged on the back side. Next, the U-shaped support portion 7 formed at one end of the arm 5 arranged on the front side is attached to the pivot shaft 8
Then, the other end of the shaft 4 of the pressure roller 3 is engaged with the U-shaped bearing portion 6 of the arm 5, and the bolt 10 is inserted into the through holes 12 and 9 of the tie bar 11 and the arm 5 for bolt insertion. Insert it. Finally, the preload package 13 is attached to the bolt 10 and the knob 14 is screwed on. Then, the pressure contact force is finely adjusted by the screwing amount of the knob 14, and the mounting of the pressure roller 3 is completed.

As described above, according to the present embodiment, the arm provided with the U-shaped support portion is used to facilitate the attachment / detachment of the arm itself to / from the pivot shaft, and the U provided on the arm as well.
Since the pressure roller shaft can be easily attached to and detached from the character-shaped bearing portion, it is possible to easily assemble and remove the pressure roller. Further, since the preload package is used as the pressure spring means, the pressure spring means can be mounted without using a special tool, and the pressure contact force of the pressure roller is set to a predetermined value by adjusting the knob. It can be easily adjusted with good reproducibility.

FIG. 3 is a schematic plan view showing the second embodiment of the present invention. The same or similar components as those in the first embodiment are designated by the same reference numerals. In this embodiment, the tie bar 11 is directly driven by the cam 17, and the bar 15 in the first embodiment can be omitted. That is, the cam shaft 16 is arranged at a position as close as possible to the tie bar 11 so as not to interfere with the operation of the preload package 13, and the cam 17 provided on the cam shaft 16 is attached to the tie bar 11.
The tie bar 11 is directly rocked by abutting against the lower surface of the cam shaft 11 to rotate the cam shaft 16. With this structure, the bar 15 in the first embodiment can be omitted, and the structure can be made inexpensive and simple.

FIG. 4 (A) is a perspective view showing a third embodiment of the present invention. Generally, the mechanism added to the pressure roller device in the image forming apparatus includes a peeling claw for preventing the recording paper from winding around the pressure roller, a cleaning blade for removing the toner adhering to the pressure roller, and a pressure roller. There are static elimination brushes, etc. that prevent the accumulation of static electricity caused by friction. These must be arranged so as to come into contact with or come close to the pressure roller at least during the image forming operation.Therefore, when attaching or detaching the pressure roller, if these additional mechanisms are provided, the attachment / detachment work is performed. Often hard to make.

The third embodiment is configured such that these additional mechanisms automatically advance and retreat to predetermined positions in association with the attachment / detachment operation of the pressure roller. That is, the peeling claw 21, the cleaning blade 22, and the charge removal brush 23, which are additional mechanisms that come into contact with or come close to the pressure roller 3, are fixed to the elongated plate-shaped support 24 by fixing means such as screws. Semi-circular bearing portions 24 ′ are formed at both ends of the support 24, and the bearing portions 24 ′ are engaged with the pivot shaft 8. Further, an engaging piece support portion is projected from one end of the support body 24 in parallel with the pivot shaft 8, and an engaging piece 25 is formed at the tip thereof.
As shown in FIG. 4 (B), when the arm 5 supporting the pressure roller shaft 4 is engaged with the pivot shaft 8, the engaging piece 25 comes into contact with the engaging end 5 ′ of the arm 5. They are arranged so that they come into contact with each other. Further, one end of the elastic body 26 is brought into contact with the engagement piece 25, and the support body 24 is urged so as to separate the additional mechanism such as the cleaning blade from the pressure roller 3.

Next, the operation of the roller pressure contact mechanism configured as described above will be described. First, as in the case of the first embodiment,
When the arm 5 is disengaged from the pivot shaft 8 to remove the pressure roller 3, the engaging end 5 ′ of the arm 5 disengages from the engaging piece 25 of the support 24, and the engaging piece 25 urges the elastic body 26. The support 24 is rotated by being pressed by, and the additional mechanism such as the cleaning blade 22 fixed to the support 24 is separated from the pressure roller 3. Therefore, even if the additional mechanism is provided, the pressure roller 3 can be easily removed.

When the pressure roller 3 is attached, the pressure roller 3 is inserted into the mechanism, and the arm 5 is engaged with the pivot shaft 8 and the pressure roller shaft 4 contrary to the above-described removal process.
Since the end portion 5'of the arm 5 pushes down the engaging piece 25 against the elastic body 26, the additional mechanism such as the cleaning blade 22 is automatically placed in a predetermined operating position in which it comes into contact with or comes close to the pressure roller 3. To be done. Therefore, after maintenance,
It is possible to prevent the possibility of forgetting to return these additional mechanisms to the operating position.

The U-shaped support portion 7 formed at the end of the arm 5 is
Instead of being formed so as to open downward at right angles to the length direction, as shown in FIG. 4 (C), a U-shaped support portion 7'is formed in the end face of the arm 5 in the length direction. Also, the same effect can be obtained. Further, as a spring used to bias the support 24, a coil spring or the like may be used instead of the spiral spring shown in the drawing.

In the first embodiment shown in FIGS. 1 and 2, the arm 5
The lower surface of the preload frame 13 _{-2 and} the uppermost surface of the preload frame 13 _-2 , which are in contact with it, are flat surfaces and are configured to make surface contact. However, when the bolt 10 is pushed up by the vertical movement of the tie bar 11 caused by the cam operation,
Depending on the gap between the 10 and the arm 5, and between the bolt 10 and the preload frame 13 _-2 , the preload package 13
May be inclined with respect to the arm 5 and the uppermost surface of the preload frame 13 _-2 and the lower surface of the arm 5 may not be in normal surface contact with each other. In this case, the pressure spring 13 _-1 does not deform normally, and a predetermined pressure contact force cannot be exerted.

FIGS. 5A to 5C show a fourth embodiment having a structure for solving this drawback. As shown in FIG. 5 (A), a pair of arc-shaped arm protrusions 27 are provided in the longitudinal direction on both sides of the through hole 9 through which the bolt 10 is inserted, on the lower surface of the arm 5. On the other hand, on the upper surface of the preload frame 13 _-2 of the preload package 13, as shown in FIG. 5 (B), the pressure spring 13 _-1 has a diameter such that it does not protrude from the preload frame 13 _-2. A circular opening _13-5 is formed. Then, fitting the ring 13 _-6 to loosely fit in the circular opening 13 _-5, through which the bolts 10 through the ring 13 _-6 to preload package 13.

With this configuration, since the arm protrusion 27 and the ring 13 _-6 are in line contact with each other, even if the preload package 13 contacts the arm 5 in an inclined state, the ring 13 _-6 does not Preload frame with pressure spring 13 _-1
Within 13 _-2 , it will be pressed straight in the normal direction, and a predetermined pressure contact force can be obtained.

Further, as shown in FIG. 5 (C), instead of the ring 13 _-6, an annular engaging portion 13 whose outer diameter is smaller than the inner diameter of the preload frame 13 _-2 and larger than the diameter of the circular opening 13 _-5.
-7 and, the small diameter of the annular projection abutment 13 _-8 than the circular opening 13 _-5 to form a contact member 13 _-9 were integrated, and the annular engagement portion of the abutment member 13 _-9 13 _-7 is located between the uppermost surface of the preload frame 13 _-2 and the pressure spring 13 _-1 , and the annular contact portion 13 _-8 is arranged so as to project from the opening 13 _-5 of the preload frame 13 _-2. And the abutting portion 13 _-8 is provided on the arm 5 to project the arm.
Even if it engages with 27, the same action and effect as those shown in FIG. 5 (B) can be obtained.
When the bolt 13 is removed from the bolt 10, the abutting member _13-9 does not come off from the preload package 13 and is lost, and the assembly and mounting work can be easily performed.

The cam means in the embodiment shown in FIGS. 1 and 3 is constituted by providing a cam shaft and a separate cam and a handle, but FIG. 6 shows a modified example of the cam means. It is a perspective view. In this modified example, the cam surface is formed integrally with the cam shaft, and the cam shaft 31 is formed in a circular cross section in the vicinity of the end of the cam shaft 31 around a position eccentric from the shaft center of the cam shaft 31. A cylindrical portion having a circular cross section that fits in is provided, and the surface of this cylindrical portion is used as the cam surface 32. Further, the cam shaft portion extending from the cam surface 32 to the end face is cut into a D-shape to form an oval-shaped portion 33, and the oval-shaped portion 33 is provided with a handle 18, a stopper 34 if necessary, and a danger prevention. Engage a cover (not shown) or the like. The cam surface 32 is the bar 15 or the tie bar 11.
The end of the camshaft 31 near the bearing 35
It is attached to the mechanism side plate through the shaft. With the cam means having this configuration, the handle 18 can be rotated to rotate the cam surface 32 and vertically move the bar 15 or the tie bar 11 in contact with the cam surface 32.

〔The invention's effect〕

As described above with reference to the embodiments, according to the present invention, it is possible to provide a roller press-contact mechanism for an image forming apparatus, which can save space in the apparatus and can easily adjust the press-contact force.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a roller pressure contact mechanism of an image forming apparatus according to the present invention, FIG. 2 is an enlarged sectional view of a preload package arrangement portion thereof, and FIG. 3 is a second embodiment of the present invention. A schematic plan view of the embodiment, FIG. 4 (A) is a partially omitted perspective view of a third embodiment of the present invention, and FIG. 4 (B) is a plan view of the contact portion between the arm and the engaging piece. FIG. 4 (C) is a plan view of the modification, FIG. 5 (A) is a rear view showing an arm portion in the fourth embodiment of the present invention, and FIG. FIG. 5C is a cross-sectional view showing the positional relationship with the preload package, FIG. 5C is a cross-sectional view showing a modification of the one shown in FIGS. 5A and 5B, and FIG. 6 is a modification of the cam means. FIG. 7 is a plan view of a conventional roller pressing mechanism, and FIG. 8 is a conceptual diagram showing the roller pressing mechanism of the present invention. In the figure, 1 is a pressure roller, 3 is a pressure roller, and 4
Is a pressure roller shaft, 5 is an arm, 6 is a U-shaped bearing portion, 7
Is a U-shaped bearing, 8 is a pivot shaft, 10 is a bolt, 11 is a tie bar, 13 is a preload package, 14 is a knob, 15 is a bar, 16 is a cam shaft, 17 is a cam, 18 is a handle, and 21 is a peeling claw. , 22 is a cleaning blade, 23 is a static elimination brush, 24 is a support, 25 is an engaging piece, 26 is an elastic body, 27 is an arm convex portion, 31
Is a cam shaft, 32 is a cam surface, and 34 is a stopper.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-112770 (JP, A) JP-A-58-126558 (JP, A) JP-A-57-133467 (JP, A) Actual publication Sho-58- 55381 (JP, Y2)

Claims (1)

[Claims] 1. A roller press-contact mechanism of an image forming apparatus for press-contacting a pair of rollers that nips and conveys a sheet, and a pressing member that presses one roller toward the other roller via a spring member, and the pressing member. A displacement means for displacing the spring member between a first position for pressing the spring member and a second position retracted from the first position; and the pressing member from the first position to the second position. A spring restricting member that receives the spring force of the spring member instead of the pressing member during displacement, and a spring provided by the pressing member when the spring restricting member receives the spring force of the spring member. An adjusting member for adjusting the pressing amount of the member, and a roller pressing mechanism for an image forming apparatus, comprising: