JPH06219565A - Bottom pushup mechanism - Google Patents

Abstract

(57) [Summary] [Purpose] In the bottom plate pushing up mechanism for pushing up the bottom plate installed in the paper cassette that is detachable from the main body of the device,
Eliminates unpleasant vibration noise when pushing up the bottom plate. A rotary shaft 22a, one end of which is supported by a side surface portion N of a device body through a one-way type rotary damper 21 and the other end of which is rotatably supported by another side surface portion of the device body, and the rotation shaft 22a. A push-up member 22 having one end fixed to the shaft 22a and the other end having a push-up plate 22b which is a free end engageable with the back surface of the bottom plate is provided. The rotating shaft 22a is biased by a tension spring 23 so as to rotate in a predetermined direction (the direction in which the push-up plate 22b pushes up the bottom plate). The one-way type rotary damper 21 exerts a braking action for slowing down the rotation speed only when the rotation shaft 22a is about to rotate in the predetermined direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is incorporated in an image forming apparatus such as a printer or a copying machine having a detachable paper feed cassette in a main body of the apparatus, and a bottom plate for pushing up a bottom plate installed in the paper feed cassette. Regarding the lifting mechanism.

[0002]

2. Description of the Related Art FIGS. 5 and 6 are an overall configuration diagram and an external perspective view of a conventional image forming apparatus (here, a printer apparatus is shown as an example). In this image forming apparatus, a paper feed cassette 1 which is detachable from the front side of the apparatus main body M in the direction of arrow A (see FIG. 6), and paper sheets stacked and stored in the paper feed cassette 1 are attached and detached to the paper feed cassette 1. A paper feed roll 2 and a separating member 3 that feed sheets while separating them one by one in a direction (arrow B direction) that intersects the direction (arrow A direction), and then re-convey at a predetermined timing after temporarily holding the fed paper. The standby roll 4, an image forming unit 5 (photosensitive drum 5a, charger 5) that forms a toner image on the conveyed sheet based on image information.
b, print head 5c, developing device 5d, transfer device 5e, cleaner 5f, etc.), and a fixing device 6 for fixing the toner image on a sheet.

Here, the paper feed cassette 1 is internally provided with a bottom plate 1a capable of pushing up the front end in the paper feed direction of the sheets stacked and stored therein, and after the paper feed cassette 1 is attached to the apparatus main body M or Simultaneously with mounting, the bottom plate 1a is pushed up by the bottom plate pushing-up mechanism of the apparatus main body, and the sheets stacked on the bottom plate 1a are biased upward so that the sheets can be fed. Examples of such a bottom plate pushing-up mechanism include those shown in FIGS. 7 and 8. As shown in the figure, a push-up member 11 formed by fixing one end of a push-up plate 11b is provided in the middle of a rotary shaft 11a rotatably supported by the apparatus main body.
The other end of 1b is a free end engageable with the back surface of the bottom plate 1a. A torsion spring 12 as an urging member is connected to the rotation shaft 11a, and the elastic force of the torsion spring 12 pushes up the push-up plate 11b via the rotation shaft 11a, and the push-up plate 11b pushes up the bottom plate 1a. (Direction of arrow C)
Urge to. Further, a stopper (blocking means) (not shown) allows the push-up member 11 to be held in the posture shown in FIG. 7B against the urging force of the torsion spring 12 in the direction of arrow C. In this state, the paper feed cassette 1 can be attached and detached in the direction of arrow A (see FIG. 6). When the paper feed cassette 1 is attached to the apparatus main body, the holding of the push-up member 11 by the stopper is released automatically or manually to push up the bottom plate 1a as shown in FIG. It is ready for paper. Note that FIG. 7 shows a configuration in which the separating member 3 can be brought into and out of contact with the paper feed roll 2 along with the vertical movement of the push-up plate 11b.

[0004]

In the conventional bottom plate pushing-up mechanism described above, when the holding of the pushing-up member 11 by the stopper is released when the sheet cassette 1 is mounted, the pushing-up member 11 is pushed by the biasing force of the torsion spring 12. Bottom plate 1a
Since the paper is pushed up at a stretch, the push-up plate 11b and the bottom plate 1a or the bottom plate 1a and the paper feed roll 2 violently collide with each other, especially when there are no papers stored in the paper feed cassette 1 or when there are few papers stored. "Gashan"
That is, there is a problem that a very loud and unpleasant vibration noise is generated, which may impair the high quality of the device.

In view of the above points, an object of the present invention is to provide a bottom plate pushing-up mechanism which eliminates unpleasant vibration noise when a cassette is mounted and enables a quiet and high-pushing operation with a high-class feeling.

[0006]

In order to achieve the above object, the present invention has a bottom plate capable of stacking sheets and pushing up a front end portion in the sheet feeding direction, and is attachable to and detachable from a mounting portion of an apparatus main body. Of the bottom plate pushing-up mechanism, the free end of the bottom plate is engaged with the bottom plate so that the bottom plate is between the non-feeding position and the feeding position above the non-feeding position. And a rotatable push-up member that is moved up and down, and is connected to the push-up member, and moves the push-up member from a first posture corresponding to the non-feeding position of the bottom plate to a second posture corresponding to the feed position of the bottom plate. An urging member for urging, a blocking means for holding the pushing-up member in the first posture against the urging force of the urging member when the paper feeding cassette is not mounted in the mounting portion, and the paper feeding cassette. Before the attachment means is attached to the attachment portion. A releasing means for releasing the holding, and a rotation speed with respect to the rotation direction of the rotation shaft, which is interposed between the support member and the rotation shaft, of the push-up member from the first posture to the second posture. And a rotary damper having a control function.

[0007]

When the paper feed cassette is attached to the main body of the apparatus, when the holding member is held by the blocking means in the first posture and the holding is released by the releasing means, the pushing member is pushed by the urging member. The posture is urged from the posture toward the second posture, and at that time, the rotation speed control function of the rotation damper acts on the rotation shaft, and as a result, the push-up member moves to the first position.
It rotates from the posture toward the second posture at a slow speed and quietly engages with the bottom plate.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a plan view and a front view, respectively, of a bottom plate lifting mechanism according to an embodiment of the present invention. The bottom plate lifting mechanism of this embodiment is applied to the image forming apparatus shown in FIGS.

In this embodiment, as shown in FIGS. 1 and 2, one end is supported by a side surface portion N of the apparatus main body through a one-way type rotary damper 21, and the other end is supported by a bearing or the like to prevent the other main body of the apparatus. Of the rotary shaft 22a rotatably supported on the side surface of the base plate, and one end of which is fixed in the middle of the rotary shaft 22a and the other end of which is engageable with the back surface of the bottom plate 1a (see FIGS. 5 and 6). Push-up member 2 including push-up plate 22b that is an end
Two are provided. The push-up plate 22b is made of a material such as a spring material and has an elastic force by itself.

The one-way type rotary damper 21 is
Only when the rotating shaft 22a is about to rotate in a predetermined direction (the direction of arrow D in FIG. 2 (b)), a braking action for slowing down the rotation speed is applied. For example, it has the configuration shown in FIG. That is, the cover 32 is attached to the cylindrical casing 31 whose one end is open.
Is fitted through an O-ring 33 so as to close the one end, and the movable body 34 is rotatably mounted inside by a fixed shaft-like boss 31a projecting from the inner center of the casing 31. A rotating body 36, which is supported and has a rotating shaft 36a having the rotating shaft 22a connected to one end thereof, is coaxially mounted on a boss-shaped shaft portion 35 projectingly provided at the center of the movable body 34. In the space between the movable body 34 and the casing 31, a viscous oil 37 such as silicon grease is provided.
Is enclosed. Furthermore, the movable body 34 and the rotating body 36 are formed by a one-way clutch mechanism including a pair of collars 38 and 39 attached to their respective outer peripheral surfaces and a coil spring 40 fitted to their outer peripheral surfaces. The rotary body 36 can be connected in one rotation direction (arrow D direction) and can be released in the other rotation direction. With this configuration, when the rotating body 36 rotates in the direction of arrow D, the rotating body 3
Since the movable body 34 is connected to 6 and the movable body 34 also tries to rotate together with the rotating body 36, a viscous resistance due to the oil 37 causes a kind of braking action. On the other hand, when the rotating body 36 rotates in the direction opposite to the direction of the arrow D, the connection between the rotating body 36 and the movable body 34 is released, and thus a light movement that does not receive viscous resistance due to the oil 37 becomes possible. The configuration of the rotary damper 21 shown in FIG. 3 is just an example, and other configurations can be adopted.

On the other hand, as shown in FIGS. 1 and 2, a spring retaining portion 22c is fixed in the middle of the rotary shaft 22a, and one end of a tension spring 23 as a biasing member is attached to the spring retaining portion 22c. It is hooked and the other end is the spring hooking part 2 on the device body side.
2d, and the elastic force of the tension spring 23 urges the rotating shaft 22a to rotate in the direction of arrow D,
As a result, the push-up plate 22b is biased in the direction in which the bottom plate 1a is pushed up (direction of arrow C in FIG. 2B).

Further, the paper feed cassette 1 (see FIGS. 5 and 6)
When not installed, the push-up member 22 is pulled by an unillustrated stopper (blocking means) to move the arrow C by the tension spring 23.
Against the urging force in the direction, as shown in FIG.
The sheet feeding cassette 1 is configured to be held in a posture (first posture) corresponding to the non-feeding position a, and in this state, the sheet feeding cassette 1 can be attached and detached in the direction of arrow A (see FIG. 6). Further, when the paper feed cassette 1 is attached to the main body of the apparatus, the holding of the pushing-up member 22 by the stopper is automatically or manually released by a releasing means (not shown).

In the bottom plate pushing-up mechanism having the above structure, when the paper feed cassette 1 is not mounted, the pushing-up member 22 is held in the first posture shown in FIG. 2A by the stopper (not shown) as described above. . When the paper feed cassette 1 is attached to the apparatus main body in this state, the stopper is released by the release means (not shown) as described above. Then, the push-up member 22 receives a biasing force in the arrow C direction by the tension spring 23, and the rotating shaft 22a tries to rotate in the arrow D direction. However, since the one-way rotary damper 21 is interposed between the rotary shaft 22a and the side surface portion N of the apparatus main body, the rotary damper 21 is used to rotate the rotary shaft 22a in the direction of arrow D. The speed control function works, and as a result, the push-up member 22 rotates in the direction of arrow C at a slow speed, gently engages with the bottom plate 1a, and then gradually pushes up the bottom plate 1a, finally. As shown in FIG. 2B, a posture (second posture) corresponding to the sheet feeding position of the bottom plate 1a is taken, and the sheet can be fed.

When removing the paper feed cassette 1 from the main body of the apparatus, the direction of the arrow C is set so that the paper feed cassette 1 is held in the first posture by the stopper (not shown) so that the paper feed cassette 1 does not hit the push-up member 22. When the operation of rotating the rotary shaft 22a in the opposite direction is performed, the rotary shaft 22a rotates in the direction opposite to the arrow D direction.
Since the speed control function according to 1 does not work, a very smooth turning operation is possible.

Therefore, according to the present embodiment, even if the holding of the push-up member 22 by the stopper is released when the paper feed cassette 1 is attached, the push-up member 22 slowly pushes up the bottom plate 1a by the action of the rotary damper 21. So
Even if the paper is not stored in the paper feed cassette 1, the push-up plate 22b, the bottom plate 1a, and the bottom plate 1a
The paper feed roll 2 and the paper feed roll 2 are engaged with each other slowly and quietly, so that it is possible to prevent the generation of an unpleasant vibration noise such as "Gashan" and to give the apparatus a high-class feeling.

Further, in this way, the push-up member 22 is slowly rotated by the action of the rotary damper 21,
An unreasonable burden is not applied to the entire bottom plate lifting mechanism, thus improving the reliability of the device.

The present embodiment can be applied to, of course, those adopting a separating paper feeding system for supplying paper by using the paper feeding roll 2 and the separating member 3 as shown in FIG. The same can be applied to a paper feed method, for example, a paper feed method using a half-moon roller and a separation claw. In addition,
When the present embodiment is applied to the one using such a half-moon roller, the sheet bundle on the bottom plate 1a is pushed down by the peripheral surface portion of the half-moon roller each time the paper is fed, and the push-up member 22 also moves downwards each time. Although it rotates in the direction opposite to the arrow C direction), the push-up member 22 must return the bottom plate 1a to the original position before the next sheet feeding is started. However, at the time of the return, the rotary shaft 22a slowly rotates while receiving the action of the rotary damper 21, and the next sheet feeding starts before the rotary shaft 22a completely returns to the original position. Therefore, in this embodiment, the push-up plate 22b itself has elasticity so that the push-up plate 22b can always urge the bottom plate 1a upward independently of the movement of the rotating shaft 22a, and the bottom plate 1a is fed at the time of sheet feeding. Even if the bottom plate 1a is pushed down, the bottom plate 1a can be immediately biased upward by restoring the elastic deformation of the push-up plate 22b, so that the rotation shaft 21a is stabilized without being delayed by the action of the rotary damper 21. Consideration is made so that paper can be fed.
In addition to making the push-up plate 22b itself elastic, this action makes the push-up plate 22b rotatable by a predetermined angle with respect to the rotary shaft 22a, as in the push-up member 22 'shown in FIG. 4, and It can also be obtained by using a structure in which the torsion spring 22e urges in the direction of arrow C. In the case of the separation sheet feeding method as shown in FIG. 5, when the sheet feeding cassette 1 is set in the sheet feedable state, the uppermost sheet of the sheet is always in pressure contact with the sheet feeding roll. The above consideration is not always necessary.

Although the tension spring 23 is used as the urging member in the above embodiment, the torsion spring 12 as shown in FIG. 8 can be used. Further, in the above embodiment, the case where the bottom plate pushing-up mechanism is provided on the apparatus main body side has been described, but it may be provided on the paper feed cassette 1 side.

Further, as the rotary damper, one having a one-way function as in the above embodiment is desirable, but the present invention can be adopted even if it does not have such a function.

[0020]

According to the present invention, when the push-up member pushes up the bottom plate when the paper feed cassette is mounted, the push-up member slowly pushes up the bottom plate by the rotation speed control function of the rotary damper. Even when the paper is not stored inside, the push-up member and the bottom plate engage with each other slowly and quietly, no unpleasant vibration noise is generated, and thus the high quality of the apparatus is maintained.

Further, since the push-up member is slowly rotated by the action of the rotary damper in this manner, the bottom plate push-up mechanism as a whole is not unduly burdened, thereby improving the reliability of the apparatus.

[Brief description of drawings]

FIG. 1 is a plan view of a bottom plate lifting mechanism according to an embodiment of the present invention.

FIG. 2 is a front view of the bottom plate lifting mechanism of the embodiment,
(A) shows the state before sheet feeding of the cassette, and (b) shows the transition to the sheet feedable state.

FIG. 3 is a cross-sectional view showing an example of a one-way rotary damper 21.

FIG. 4 is a perspective view showing an example for giving elasticity to a push-up plate 22b.

FIG. 5 is an overall configuration diagram of a conventional image forming apparatus.

FIG. 6 is an external perspective view of the conventional image forming apparatus shown in FIG.

7A and 7B are cross-sectional views of a sheet feeding unit including a conventional bottom plate lifting mechanism, FIG. 7A shows a state in which sheets can be fed, and FIG. 7B shows a state before sheet feeding.

8A and 8B are diagrams schematically showing a conventional bottom plate lifting mechanism, where FIG. 8A is a plan view and FIG. 8B is a front view.

[Explanation of symbols]

 1 Paper feed cassette 1a Bottom plate 2 Paper feed roll 21 Rotation dampers 22 and 22 'Push-up member 22a Rotating shaft 22b Push-up plate 23 Tension spring

Claims (1)

[Claims] 1. A bottom plate pushing-up mechanism of a sheet feeding cassette, which is equipped with a bottom plate capable of stacking sheets and pushing up a front end portion in the sheet feeding direction, and which is detachably mountable to a mounting portion of an apparatus main body. A rotating shaft supported by a supporting member. A rotatable push-up member having a free end that moves up and down between the non-feeding position and a paper feeding position above the non-feeding position by engaging the bottom plate with the bottom plate; An urging member that is connected and urges the push-up member from a first attitude corresponding to a non-paper feeding position of the bottom plate to a second attitude corresponding to a paper feeding position of the bottom plate; and the mounting portion of the paper feeding cassette. Blocking means for holding the pushing-up member in the first posture against the biasing force of the biasing member when not mounted on the loading cassette, and holding by the blocking means when mounting the paper feed cassette on the mounting portion. Release means for releasing, the support member and the A rotary damper that is interposed between the rotary shaft and a moving shaft and has a rotation speed control function with respect to the rotation direction of the rotary shaft from the first posture to the second posture of the push-up member. Bottom plate lifting mechanism.