JP5428393B2 - Fixing apparatus and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine or a printer having a configuration for increasing or decreasing a pressure applied between two rollers, and an image forming apparatus using the fixing device.

Image forming apparatuses such as copiers and printers have high needs for miniaturization and high speed. To meet such needs, the fixing device to be mounted is downsized, the linear speed is increased to speed up the operation of the image forming apparatus, and this demand is being met without degrading the image quality. However, if the size of the fixing device is reduced, the pressure applied to the fixing device is increased, and the following inconvenience occurs during jam processing and other maintenance.
In such a fixing device, when jam processing or other maintenance is required, the pressure of the two rollers in pressure contact must be released, and this pressure release can be performed without using a control lever. Like to do.

FIG. 12 is a schematic view in which a short lever is employed to increase the pressing force of the fixing device. FIG. 13 is a schematic view in which a long lever that protrudes from the fixing device is used to increase the pressure of the fixing device.
As shown in FIG. 12, when a lever that is used to increase the pressing force of the fixing device for the purpose of miniaturization is used and a short lever that can be accommodated in the fixing device is used, a user with relatively weak force becomes more jammed as the pressing force increases. Sometimes it becomes difficult to release the pressure between the rollers of the fixing device.
In addition, as shown in FIG. 13, when a long lever that protrudes from the fixing device is used so that the pressure state can be easily released, when the fixing device is pulled out or removed from the image forming apparatus, the lever is in a protruding state and jammed. It is dangerous because the hand gets caught on the lever during maintenance such as processing.
In order to eliminate the inconveniences of the configuration described in FIGS. 12 and 13 and satisfy the demand for downsizing and high speed, various image forming apparatuses have been proposed in the past focusing on the pressure applied to the fixing device. (For example, refer to Patent Document 1).

FIG. 14 is a diagram schematically illustrating a conventional fixing device. FIG. 14 shows an outline of the configuration of the fixing device described in Patent Document 1. In FIG. 14, a first roller 1 and a second roller 2 are shown. For example, the first roller 1 can be a fixing roller and the second roller 2 can be a pressure roller.
The first roller 1 is fixed to a side plate (not shown), and the second roller 2 is pressed against the first roller 1 using the tensile force of the spring 3. Bearings are attached to both ends of the second roller 2 in the axial direction, and the sheet metal 4 is in contact with the bearing portion of the second roller 2.
The sheet metal 4 has a hole 4 b for hooking the shaft 4 a and the spring 3. The shaft 4a is fixed to a side plate (not shown), and the second roller 2 is pressed against the first roller 1 by the tensile force of the spring 3 that is applied to the hole 4b.
One end of the spring 3 is engaged with the hole 4b of the sheet metal 4 as described above. The other end of the spring 3 is hooked on a pin 6 inserted in the hole 5 b of the lever 5. The lever 5 has a shaft 5 a and a handle 5 c in addition to the hole 5 b for the pin 6. The lever 5 is fixed to a side plate (not shown) by a shaft 5a.

By holding the handle 5c portion of the lever 5 and rotating it in the direction A in FIG. 14 (a), it is possible to switch between the pressurized state and the pressure released state. FIG. 14A shows a pressurized state, and FIG. 14B shows a pressure released state. In FIG. 14B, the first roller 1 and the second roller 2 are separated from each other when the pressure is released, but may be in a low pressure state without being separated.
As the image forming apparatus becomes smaller and faster, there is a tendency to use a stronger spring as a spring for mooring the sheet metal 4 and the lever 5, and it is becoming difficult for anyone to easily release without using a tool. is there.
FIG. 14 (c) shows a perspective view of the lever 5, and shows a shaft 5a, holes 5b1, 5b2, and a hand-held portion 5c. In FIG. 14C, when the holes 5b1 and 5b2 of the lever 5 are compared, 5b1 is larger. The pin 6 can be inserted and removed only from the B direction in FIG.
FIG. 14 (d) is a perspective view showing a state where the pin 6 is inserted into the holes 5b1, 5b2, and FIG. 14 (e) is a view of FIG. 14 (d) as viewed from above. In FIGS. 14C and 14D, the spring is omitted (not shown), but actually, the spring 3 is located on the pin 6 inside the lever 5 as shown in FIG. 14E.

However, as described above, image forming apparatuses such as copiers and printers have high needs for downsizing and high speed. In response to such needs, the size of the fixing device to be mounted is reduced, and the linear speed is increased. We are trying to meet this demand without losing image quality by speeding up the operation. However, if the size of the fixing device is reduced, the pressure applied to the fixing device is increased, and the following inconvenience occurs during jam processing and other maintenance.
However, the downsizing of the fixing device requires the release of the increased pressure between the two rollers. As the pressure increases, a relatively weak person such as a woman, elderly person, or younger person may apply pressure during jam processing. It is difficult to release the pressure state. It is not convenient for a user to call a service person without releasing the pressurized state by himself.
If the pressure cannot be released by hand (without a tool), the handle can be released by holding the handle with a tool such as pliers, but the handle will be deformed, and if touched, it may be injured or pressurized. There is a problem of disappearing.

On the other hand, the force required for releasing the pressure can be reduced by lengthening the lever and extending the distance between the fulcrum and the force point, but there are disadvantages as described above. In addition, as described in Patent Document 1, if there is an insertion hole for inserting a tool, the pressure can be released with a small force using a tool such as a screwdriver, but the pressure is released without using a tool. There is a demerit that it cannot be done.
Furthermore, if a configuration that can automatically pressurize and release the pressure is added, the jam processing becomes easy without bothering the user. However, there are disadvantages such as an increase in cost and the complexity and size of the apparatus.
As described above, it is well known that a tension spring is used to fix both ends of a spring and obtain a pressing force for pressing the rollers together. Further, it is known that a method of fixing a spring through a pin through a pin is easy to remove the pin and replace the spring.

However, if the pin can be easily removed by simply pulling out the pin in the pressure released state, for example, when carrying the fixing device in the pressure released state, there is a problem that the pin is easily removed and easily lost. When the jam is released, if the user releases the pressure and loses the pin, the device cannot be used until the service person repairs it, which is inconvenient.
In order to prevent the pin from coming off, it is possible to prevent the pin from being lost by screwing another sheet metal to the outside of the pin hole. However, if the screw is not removed with a screwdriver, the pin cannot be removed and the spring cannot be replaced. Therefore, the working time is increased as compared with the case where there is no sheet metal + screw for preventing loss.
In view of the above situation, the object of the present invention is to release the pressure with a small force without using a tool, and to easily remove the pin and replace the spring. An object of the present invention is to provide a fixing device capable of preventing loss and an image forming apparatus equipped with the fixing device.

In order to solve the above-mentioned problem, the invention described in claim 1 is a fixing device in which outer peripheral surfaces of a first roller and a second roller having rotation centers parallel to each other are pressed against each other by a biasing force of a spring. A first lever for use in biasing or releasing the spring at the time of switching operation between the pressure contact state and the pressure release state; and a second lever that can be pulled out and stored from the first lever. And has a pin that is inserted through the hole and hooks one end of the spring. The pin is not fixed at all times. When the second lever is housed in the first lever, the second lever closes the hole. When the pin cannot be inserted / removed and the second lever is pulled out from the first lever , the hole is exposed and the pin can be inserted / removed.
According to a second aspect of the present invention, there is provided the fixing device according to the first aspect, wherein the second lever is housed in the first lever when the pressure is released.
According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the second lever has a notch in a part thereof so that the pin can be inserted and removed when pulled out. Features.
According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the second lever has a bent portion, and the bent portion moves the second lever to the second lever. It is characterized by being adjacent to the bent portion of the first lever in parallel with the length direction in the state of being accommodated in the first lever.
According to a fifth aspect of the present invention, there is provided an image forming apparatus including the fixing device according to any one of the first to fourth aspects.

  According to the present invention, since the second lever that facilitates the switching operation between the pressure contact state (high pressure state) and the release state (low pressure state) is provided, the switching operation can be performed without using a tool with a small force. Easy to use.

1 is a schematic diagram showing an embodiment of an image forming apparatus to which the present invention can be applied. FIG. 3 is a schematic perspective view illustrating a positional relationship among an image forming apparatus, a fixing device, and a pressure lever. It is a perspective view which shows the movement of a pressurization lever. 1 is a perspective view showing a first embodiment of a pressure lever of the present invention together with two rollers of a fixing device. It is a perspective view which shows the pressurization lever of FIG. It is a top view which shows the relationship between a 1st lever and a 2nd lever. It is a schematic perspective view which shows the example of attachment of two levers. FIG. 4 is a schematic diagram illustrating a first lever and a second lever in a pressure release state of a roller of the fixing device. It is the schematic which shows the overlap of a 1st lever and a 2nd lever when a 2nd lever is pulled out. It is the schematic which shows the 2nd lever which has another bending part. It is a perspective view which shows the 2nd lever which has the other bending part of FIG. FIG. 3 is a schematic diagram that employs a short lever to increase the pressure applied by the fixing device. FIG. 3 is a schematic view that employs a long lever that protrudes from the fixing device to increase the pressure applied by the fixing device. It is a figure which shows the conventional fixing device simply.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of an image forming apparatus to which the present invention can be applied. In the image forming apparatus A of FIG. 1, the photosensitive drums 1Y, 1M, 1C, and 1K, which are image carriers, rotate in the direction of the arrow. The subscripts Y, M, C, and K indicate yellow, magenta, cyan, and black, respectively.
Around each of the photosensitive drums 1Y, 1M, 1C, and 1K, charging members 2Y, 2M, 2C, and 2K that are charging means in the order of rotation, developing devices 4Y, 4M, 4C, and 4K, transfer charging means 6Y, 6M, 6C, 6K and cleaning means 5Y, 5M, 5C, 5K are arranged.
The charging members 2Y, 2M, 2C, and 2K constitute a charging device for uniformly charging the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K. The surface of the photosensitive drums 1Y, 1M, 1C, and 1K between the charging members 2Y, 2M, 2C, and 2K and the developing devices 4Y, 4M, 4C, and 4K is irradiated with a beam by the writing unit 3, and the photosensitive drum 1Y. An electrostatic latent image is formed on the surface of 1M, 1C, and 1K.
Then, based on the electrostatic latent image, toner images are formed on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K by the developing devices 4Y, 4M, 4C, and 4K. Further, recording paper (transfer material) fed from a paper supply unit (not shown) by transfer charging means 6Y, 6M, 6C, 6K as transfer bias applying means for applying a bias to the transfer belt 8 as transfer means. The respective color toner images are sequentially transferred to an unillustrated image, and finally the image is fixed on the recording paper by the fixing device 9 including the fixing roller 9a and the pressure roller 9b.

FIG. 2 is a schematic perspective view showing a positional relationship among the image forming apparatus, the fixing device, and the pressure lever. FIG. 3 is a perspective view showing the movement of the pressure lever. 1 is arranged at a predetermined position in the image forming apparatus main body 10, and the fixing device 9 opens the opening / closing lid 11 provided on the side surface of the image forming apparatus main body 10 as shown in FIG. The image forming apparatus main body 10 is arranged so as to be drawn out. The fixing device 9 is provided with a pressure lever 12.
The fixing device 9 is pulled out from the image forming apparatus body 10 by opening the opening / closing cover 11 from the initial state (FIG. 2A) in which the opening / closing cover 11 provided on the side surface of the image forming apparatus body 10 is closed. b)). In that case, the pressure lever 12 is in the initial state of FIG.
Thereafter, the pressure lever 12 is slid in the pulling direction (FIG. 2C) and (FIG. 3B), and further, the pressure lever 12 is rotated upward to release the pressure of the fixing device 9 (FIG. 2). 3 (c)).
Although not shown, the pressure lever 12 may be arranged in the fixing device 9 so as to slide upward. In this case, after being pulled out from the image forming apparatus main body 10, it is slid upward and then downward. The pressure of the fixing device 9 may be released by rotating.

FIG. 4 is a perspective view showing a first embodiment of the pressure lever of the present invention together with two rollers of the fixing device. FIG. 5 is a perspective view showing the pressure lever of FIG. In FIG. 4, the first roller 9a and the second roller 9b of the fixing device 9 are shown. For example, the first roller 9a can be a fixing roller and the second roller 9b can be a pressure roller.
The first roller 9a is fixed to a side plate (not shown), and the second roller 9b is pressed against the first roller 9a using the tension force of the spring 13 (pressurized state). Bearings are attached to both ends of the second roller 9b in the axial direction, and the sheet metal 14 is in contact with the bearing portion of the second roller 9b.
The sheet metal 14 has a shaft 14 a and a hole 14 b for hooking the spring 13. The shaft 14a is fixed to a side plate (not shown), and the second roller 9b is pressed against the first roller 9a by the tensile force of the spring 13 that is applied to the hole 14b.
One end of the spring 13 is engaged with the hole 14b of the sheet metal 14 as described above. The other end of the spring 13 is hooked on a pin 16 (FIG. 4) inserted into the holes 12b1 and 12b2 (FIG. 5) of the first lever 12. The first lever 12 is fixed to a side plate (not shown) by a shaft 12a.

In FIG. 5, a pressure lever composed of a first lever 12 and a second lever 15 is shown. The first lever 12 is provided with a second lever 15 that can be pulled out and stored. The second lever 15 has a handle portion 15a. FIG. 5 shows a state in which the second lever 15 is pulled out from the first lever 12 (FIG. 5A), and a storage state in which the second lever 15 is stored in the first lever 12 (FIG. 5B). Is shown in a perspective view.
The first lever 12 is pivotally supported by a shaft 12a, and is provided so as to be rotatable around the shaft 12a. In order to maintain the first lever 12 in the state shown in FIG. 4, a stopper for stopping the rotation of the first lever 12 is required at an appropriate position, but it is not shown here.
FIG. 6 is a plan view showing the relationship between the first lever and the second lever. FIG. 6A shows a state where the second lever 15 is pulled out, and FIG. 6B shows a state where the second lever 15 is stored. In this stored state, the hole 12 b 1 that stores the pin 16 is closed by the second lever 15.

FIG. 7 is a schematic perspective view showing an example of attachment of two levers. In FIGS. 4, 5, and 6, how the second lever 15 is attached to the first lever 12 is omitted. For example, as shown in FIG. 7A, a long hole is made in one sheet metal corresponding to the first lever 12, and another sheet metal corresponding to the second lever 15 is bent to prevent it from coming off.
As shown in FIG. 7B, by combining these two sheet metals, they can be pulled out and stored in each other. Conventional techniques can be applied to such a configuration. In FIG. 4 and subsequent figures, how the second lever is attached to the lever is also omitted.
When switching between the pressurization state and the pressure release state, the distance from the shaft 12a to the operation position is established by pulling the second lever 15 with the handle portion 15a as shown in FIG. 6 (a). Will increase. That is, the distance from the shaft 12a to the handle portion 15a in FIG. 6 (a) is longer than the distance from the shaft 12a to the handle portion 12c in FIG. 6 (b).
Because of the lever principle, the handle portion 15a of the second lever 15 can be operated with a smaller force than the handle portion 12c of the first lever 12, and a tool must be used during the operation. Absent.
If the second lever 15 is provided in this way, the second lever 15 can be pulled out and the pressure / pressure release operation can be easily performed without using a tool. Of course, the second lever 15 can be operated by grasping the handle portion 12c of the first lever 12 without pulling out the second lever 15.

FIG. 8 is a schematic diagram showing the first lever and the second lever when the pressure of the roller of the fixing device is released. FIG. 8 shows a portion corresponding to a portion surrounded by a dotted line in FIG.
The second lever 15 can be easily pulled out as shown in FIG. 8A. When the second lever 15 is released after the pressure release operation, the second lever 15 is stored as shown in FIG. 8B due to gravity. Since the second lever 15 does not remain protruded, it is safer than staying protruded without inadvertently catching a hand on the protruding portion and causing injury.
Further, when the second lever 15 is stored, the hole 12b1 of the first lever 12 is closed and the pin 16 cannot be pulled out, so there is no possibility of losing the pin as in the conventional example. When the spring is replaced, the spring can be replaced by pulling out the second lever 15 with one hand and pulling out the pin 16 with the other hand.
Since the second lever 15 does not remain pulled out when the pressure is released, the safety is higher than when the second lever 15 remains pulled out. In a state where the second lever 15 is housed, the pin 16 cannot be pulled out, so that the pin 16 can be prevented from being lost.
Here, the first lever 12 and the second lever 15 are described as being slidable, but other than that, although not shown, the second lever 15 is parallel to the side of the first lever 12 when the lever is housed. Folding and lever pulling method, the second lever 15 is stacked in the length direction of the first lever 12 when the lever is pulled out, the second lever 15 is arranged parallel to the side of the first lever 12 when the lever is retracted, A lever fishing rod system or the like that pulls out one lever 12 from the position can also be adopted.

FIG. 9 is a schematic view showing the overlap between the first lever and the second lever when the second lever is pulled out. As shown in FIG. 9 (a), when the second lever 15 is pulled out, if the range 17 (shaded portion in FIG. 9 (a)) where the first lever 12 and the second lever 15 overlap is too small, strong force is applied. When added, the second lever 15 may come off the first lever 12. The pin 16 is accommodated in the hole 12b1.
As shown in FIG. 9B, if the overlapping portion is simply extended, it overlaps with the pin 16 in the hole 12b1, and the pin 16 cannot be inserted or removed even if the second lever 15 is pulled out. Although the position of the pin 16 may be changed as shown in FIG. 9C, the position of the pin 16 cannot always be changed.

Therefore, as shown in FIG. 9D, the position of the pin 16 is not changed, and the position of the pin 16 is not changed from the case of FIG. Since the range in which the first lever 12 and the second lever 15 overlap (shaded portion in FIG. 9D) 18 can be increased, the second lever 15 can be made difficult to come off from the first lever 12.
FIG. 9D shows the second lever 15 having a part 15b with a part cut away, and FIG. 9E shows the second lever 15 being retracted. FIG. 9D and FIG. 9E show the second lever 15 having the same shape. Moreover, it is good also as the hole 15c like FIG.9 (f) instead of a notch part.
Thus, since the notched portion 15b is provided in the second lever 15 and the contact portion 18 between the second lever 15 and the first lever 12 is increased, there is an advantage that the second lever 15 is unlikely to be detached from the first lever 12. is there.

FIG. 10 is a schematic view showing a second lever having another bent portion. FIG. 10A shows when the second lever 15 is pulled out, and FIG. 10B shows when the second lever 15 is stored. The second lever 15 is provided with a bent portion 15c (shaded portion, second hand-held portion) extending in parallel with the handle portion 12c at a portion overlapping the handle portion 12c of the first lever 12. This has the advantage that the strength of the second lever 15 is increased.
FIG. 11 is a perspective view showing a second lever having another bent portion of FIG. FIG. 11A shows when the second lever 15 is pulled out from the first lever 12, and FIG. 11B shows when the second lever 15 is stored in the first lever 12.
FIG. 11 shows a hand-held portion 12c of the first lever 12, holes 12b1 and 12b2 for inserting pins 16 (not shown), a hand-held portion 15a of the second lever 15, and another bent portion (second hand-held portion) 15b. Show. The pin 16 penetrates the holes 12b1 and 12b2 similarly to FIG. 14c illustrating the conventional example.

Regarding the hand-held portion 12c, the hand-held portion 15a, and the other bent portion (second hand-held portion) 15b, the hand-held portion 15a of the second lever 15 is used to pull out the second lever 15 from the first lever 12 (usage method A). In order to release the pressure in the state where the second lever 15 is pulled out from the first lever 12, the second lever 15 is used by holding the other bent portion (second hand-held portion) 15b alone (usage method B), and the second lever 15 In the case where the pressure is released while the container is stored, the handheld portion 12c and the other bent portion (second handheld portion) 15b are both used (usage method C).
Further, the bent portion 15b of the second lever 15 overlaps the handle portion 12c of the first lever 12, so that the handle portion is deformed when the pressure release operation is performed while the second lever 15 is stored. There is also an advantage that it becomes difficult. Thus, in the state where the second lever 15 is housed in the first lever 12, the handle portions of the second lever 15 and the first lever 12 overlap with each other, so that the strength of the handle portion increases and is not easily deformed.
In the image forming apparatus using the fixing device described above, the pressure can be released with a small force without using a tool, and it is easy to switch between the pressure contact state and the pressure release state, and the spring is replaced by removing the pin. It is easy to use and can prevent pin loss.

  A image forming apparatus, 9 fixing device, 9a first roller, 9b second roller, 12 first lever, 12a shaft, 12b hole, 12c bent part (hand-held part), 13 spring, 15 second lever, 15a hand-held part, 15b Notched part, 15c Bent part (other hand-held part), 16 pins

Japanese Patent No. 3245249

Claims (5)

In the fixing device in which the outer peripheral surfaces of the first roller and the second roller having rotation centers parallel to each other are brought into pressure contact with each other by a biasing force of a spring, a first lever for use in switching operation between the pressure contact state and the pressure release state is provided. And a second lever that can be pulled out and stored from the first lever, and has a pin that is inserted through the hole of the first lever and hooks one end of the spring, and the pin is not always fixed, When the second lever is housed in the first lever, the second lever closes the hole and the pin cannot be inserted and removed, and when the second lever is pulled out from the first lever , the hole is not A fixing device, wherein the fixing device is exposed and can be inserted and removed.   The fixing device according to claim 1, wherein the second lever is housed in the first lever when the pressure is released.   The fixing device according to claim 1, wherein the second lever has a notch at a part thereof so that the pin can be inserted and removed when the second lever is pulled out.   The second lever has a bent portion, and the bent portion is adjacent to the bent portion of the first lever in parallel with the length direction in a state where the second lever is housed in the first lever. The fixing device according to any one of claims 1 to 3.   An image forming apparatus comprising the fixing device according to claim 1.

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