JP2964602B2 - Paper transport device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device that can be suitably applied to a fixing unit or the like in an image forming apparatus such as a printer or a copying machine.

(Prior Art) Generally, a fixing unit of an image forming apparatus is configured to press a movable roller against a fixed roller having a built-in heater, and press a separation claw against the fixed roller and the movable roller. This prevents the paper from being wound around these rollers.

In addition, since the fixed roller is fixedly installed and the movable roller is slightly movable, the structure of the sheet separating device for preventing the sheet from winding around these rollers is shown in FIG. Then, a rigid separating claw 33 is pressed against the fixed roller 31 by a biasing means 34, and the movable roller
An elastic separation claw 35 made of an elastic material is fixedly provided so as to be pressed against the end of the movable roller 32 so as to follow the movement of the movable roller 32.

JP-A-59-94772 discloses a configuration in which rigid separation claws are pressed against a pair of rollers by urging means and the separation claws are configured to be able to be pressed and separated. I have.

(Problems to be Solved by the Invention) However, the elastic separation claw 35 fixed to the movable roller 32
In such a case, the movable roller 32
It is necessary to remove the claw support plate 36 to which the elastic separation claw 35 is attached at the time of replacement, and at that time, the elastic separation claw 35 may be damaged, or the movable roller 32 having a relatively soft rubber lining may be damaged. There is a problem. Also,
Although a stopper 37 is provided to regulate the upper limit of the movement of the movable roller 32 when the upper fixing unit is opened upward,
Therefore, when setting the spring 38 for urging the movable roller 32, it is necessary to bend with a force of several tens of kilograms or more, and there is a problem that a special jig is required and complicated work is required.
In addition, when the upper fixing unit is opened to perform jam processing and cleaning of the claw portion, the movable roller 32 moves to the upper limit, and the elastic separation claw 35 remains pressed against the movable roller 32 at that time. Excessive pressure acts on the separation claw 35, and if it is repeated many times, plastic deformation may occur, which may result in poor pressure contact. Further, the toner and paper powder adhering to the movable roller 32 may be removed by the elastic separation claw 35.
There is a problem that cleaning is also difficult because the toner easily accumulates on the back surface and the contact portion with the movable roller 32.

As disclosed in Japanese Unexamined Patent Publication No. 59-94772, a device that presses and separates a rigid separation claw does not cause the above problem, but not only has a complicated structure, but also has a movable surface with a soft surface. Rollers have a problem that it is more difficult to achieve both separation performance and abrasion resistance than those using elastic separation claws.

The present invention has been made in view of the above-described conventional problems, and in a paper transport apparatus using an elastic separation claw, an elastic separation claw is deformed,
It is an object of the present invention to provide a sheet transporting apparatus capable of easily performing operations such as roller replacement and jam removal without damaging the rollers.

(Means for Solving the Problems) In order to achieve the above object, the present invention is configured such that the fixed roller supported by the first frame and the fixed roller supported by the second frame are floating supported in the near and far directions, and In a paper transport apparatus provided with a movable roller urged by an urging means so as to press against the fixed roller and an elastic separation claw pressed against the movable roller, the fixed roller and the movable roller are separated from each other. The first, in order to be accessible
While the second frame is provided so as to be swingable around the fixed axis,
The elastic separation claw is swingably mounted around the fixed axis so that the elastic separation claw can be moved in the near and far directions with respect to the movable roller.

(Operation) In the present invention, the first and second frames can swing around the fixed axis, so that the fixed roller and the movable roller can be separated from each other. Further, the elastic separating claw is swingable around the fixed shaft center, whereby the elastic separating claw is movable in the near and far directions with respect to the movable roller.

(Reference Example) First, another invention relating to the fixing device created by the present inventor prior to the present invention will be described with reference to FIGS. 1 to 3 as a reference example.

In FIG. 1, reference numeral 1 denotes an upper fixing unit, and a fulcrum 3
At the lower fixing unit 2 so as to be openable and closable.
The upper fixing unit 1 is provided with a fixed roller 5 having a built-in heater lamp 4. 7 is a thermistor for detecting the surface temperature of the fixed roller 5, and 8 is a thermal fuse.
Further, the lower fixing unit 2 is provided with a movable roller 6 which is supported in a floating state in a far and near direction, that is, a vertical direction with respect to the fixed roller 5, and is urged by a spring 9 so as to be pressed against the fixed roller 5. ing. The cleaning roller 10 is in contact with the movable roller 6.

A pre-fixing guide plate 11 is disposed immediately below the paper passing path passing between the fixed roller 5 and the movable roller 6.
The pre-fixing guide plate 11 is provided at the upper fixing unit 1 at one end on the upper side thereof so as to be vertically swingable at a fulcrum 12 and the other end is urged upward by a spring 13. The other end abuts on the positioning portion 14 thus positioned. In addition, an upper guide rib 15 is provided at an upper portion of the lower side of each of the rollers 5 and 6 in the paper passing path, and a lower guide rib 16 is provided at a lower portion.
Further, a discharge roller 17 and a discharge roller 18 are disposed above and below the lower position. The discharge rollers 17 are supported by roller holders 19. Further, a discharging brush 20 is provided outside the discharging roller 17.

At the top of the paper passage between the fixed roller 5 and the discharge roller 17,
A separation claw 21 having rigidity to be in pressure contact with the outer periphery of the fixed roller 5 is disposed so as to be able to press and separate and swing, and is urged by a spring 22 in the pressure contact direction. A swing support plate 23 that is swingably supported around the rotation axis of the discharge roller 18 is disposed below the paper passage between the movable roller 6 and the discharge roller 18. The lower guide rib 16 is mounted on the plate 23, and an elastic separation claw 24 that is pressed against the movable roller 6 by a repulsive force due to its own elastic deformation is mounted. The elastic separation claw 24 is made of, for example, a stainless steel thin plate. or,
The swing support plate 23 is urged downward by a spring plate 25 provided so as to protrude downward from both sides of the upper fixing unit 1, and abuts on a positioning portion 26 provided on the lower fixing unit 2. It is positioned at a predetermined position by touching.

In FIG. 1, 27 is a fixing upper cover, and 28 is an upper unit of the copier main body. In FIG. 3, reference numeral 29 denotes a discharge roller driving gear, and reference numeral 30 denotes a fixing driving gear.

According to the above configuration, the sheet conveyed along the pre-fixing guide plate 11 usually passes between the fixed roller 5 and the movable roller 6, and the unfixed image is fixed, and is discharged by the discharge roller 18 and the discharge roller 17. Is done. However, if the fixed roller 5 is dirty with toner or the like or the sheet is curled upward, the sheet may be wrapped around the fixed roller 5 and cause a jam. be able to. Similarly, the movable roller 6 is dirty with toner or the like,
When the sheet is curled downward, the sheet may be wrapped around the movable roller 6 to cause a jam, but this can be prevented by the elastic separation claw 24.

The elastic separation claw 24 can effectively absorb the variation in the mounting position accuracy of the fixed roller 5 and the movable roller 6 and the change in the position of the movable roller 6 due to the thickness of the sheet by the elastic deformation with good followability. Further, even if the position of the movable roller slightly changes during rotation, the movable roller follows the position smoothly, so that the separating operation can be maintained.

When the upper fixing unit 1 is opened as shown in FIG. 2 for a jam clearance or replacement of the movable roller 6, the movable roller 6 moves upward by the urging force of the spring 9. At this time, since the swing support plate 23 supporting the elastic separation claw 24 can swing upward around the axis of the discharge roller 18, the swing support plate 23 swings upward by the release of the pressing force by the spring plate 25, and The pressing force of the separation claw 24 is released. Since the guide plate 11 before fixing is no longer regulated by the positioning unit 14 provided in the upper fixing unit 1, the guide plate 11 is swung upward by the spring 13 and the movable roller 6 is moved. Is spring 9
Is lifted until it is free.

When closing the upper fixing unit 1, first, the fixing roller 5
Pushes down the movable roller 6. The elastic separation claw 24 that is in contact with the movable roller 6 by its own weight swings downward together with the movable roller 6, and is further pushed down by the spring plate 25 until the swing support plate 23 comes into contact with the positioning portion 26. The movable roller 6 is pressed against the outer peripheral surface of the movable roller 6 by its elastic repulsion.

Here, as a specific numerical example, the pressing force of the elastic separation claw 24 on the movable roller 6 per one roller is about 20 g. In the illustrated example, four elastic separation claws 24 are provided. The force always acts on the swing support plate 23. Then, when the leading end of the sheet collides with the leading end of the elastic separation claw 23 during the copying operation, a reactive force of 300 to 400 g acts on the swing support plate 23 as an actually measured value. Therefore, the biasing force of one spring plate 25 is set to 400 g on both sides and 400 g,
The elastic separation claw 23 is prevented from rising.

As described above, in the present embodiment, when the upper fixing unit 1 is opened, the elastic separation claw 24 can be retracted upward together with the swing support plate 23, and the elastic separation claw 24 is largely deformed to generate plastic deformation. The replacement operation and the cleaning operation can be performed without causing the movable roller 6 to be damaged. Further, the spring 9 for urging the movable roller 6 can be set by simply dropping it into the lower fixing unit 2, and a complicated setting operation is not required.

Embodiment An embodiment in which the present invention is applied to a fixing device will be described below with reference to FIG.

In the above reference example, an example is shown in which the upper fixing unit 1 is configured to be openable and closable around a fulcrum 3 disposed on the upper side of the paper path, but as shown in FIG. It can also be configured to be openable and closable. In this case, the swing support plate 23 can be integrated with the upper fixing unit 1 so as to swing integrally with the fixing unit 1.

According to this embodiment, when the upper fixing unit 1 is closed, the elastic separation claw 24 first comes into contact with the movable roller 6, and when the elastic deformation amount reaches a predetermined pressure contact force, the fixed roller 5
Comes into pressure contact with the movable roller 6. In this case, there is an advantage that the spring plate 25 becomes unnecessary and the opening and closing operation of the swing support plate 23 becomes unnecessary as compared with the above-described reference example.

(Effects of the Invention) According to the present invention, as is apparent from the above description, the fixed roller can be retracted and the elastic separation claw can be swung about the fixed shaft center which is the center of its swing. By separating the movable roller from the movable roller, when performing roller replacement, jam clearance, cleaning of the elastic separation claw, etc., the work can be easily performed without damaging the roller or deforming the elastic separation claw. it can. Moreover, the fixed shaft core is the first,
Since it is commonly used as the second frame swing shaft and the swing shaft of the elastic separation claw, simplification of the device configuration can be realized.

[Brief description of the drawings]

1 to 3 show a fixing unit of an image forming apparatus as a reference example of the present invention. FIG. 1 is a vertical sectional front view, FIG. 2 is a vertical sectional front view with the upper unit opened, and FIG. FIG. 4 is a perspective view of the fixing unit, FIG. 4 is a vertical sectional front view of the fixing unit according to the embodiment of the present invention with an upper unit opened, and FIG. 5 is a vertical sectional front view of a conventional fixing unit. 1 Upper fixing unit 2 Lower fixing unit 5 Fixed roller 6 Movable roller 9 Spring 23 Swing support plate 24 Elastic separation claw.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 13/20 G03G 15/20 B65H 29/54 G03G 15/00 510-534 B41J 13/02

Claims (1)

(57) [Claims] 1. A fixed roller supported by a first frame and a floating roller supported in a far and near direction with respect to the fixed roller supported by a second frame, and biased by an urging means so as to be pressed against the fixed roller. In a paper transport device provided with a biased movable roller and an elastic separation claw that presses against the movable roller, the first and second frames are fixed so that the fixed roller and the movable roller can be separated from each other. The elastic separation claw is mounted so as to be swingable around the fixed axis while being provided so as to be able to swing around the axis, while allowing the elastic separation claw to be movable in the distance direction with respect to the movable roller. Paper transport device.