JP3259747B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder installed in an image forming apparatus such as a printer, a copying machine, a facsimile or the like.

[0002]

2. Description of the Related Art FIGS. 12 and 13 show an example of a conventional paper feeder. The feed roller 1 and the drive roller 2 are gears 3a,
The feed gear 5 is connected to the motor 4 via an idle gear train 3 composed of 3b and 3c. The feed gear 5 transmits rotation to the feed roller 1 via an electromagnetic clutch 6. When a paper feed command is sent, the electromagnetic clutch 6 is turned on, and the paper feed roller 1 and the drive roller 2 rotate to supply the paper 7. When the leading end of the sheet 7 reaches the driving roller 2, the electromagnetic clutch 6 is turned off, the sheet feeding gear 5 is idled, and only the gear 2a is driven. Is done. Therefore, the paper 7 is not conveyed by the paper feed roller 1 and the second and subsequent papers remain in the tray 8 to prevent continuous paper feeding.

[0003]

However, since the conventional paper feeder uses the electromagnetic clutch 6, it tends to be expensive. Also, the electromagnetic clutch 6 is turned on / off.
There is also a drawback that an electric circuit for performing the operation is required and the cost is high. In view of such circumstances, an object of the present invention is to provide a sheet feeding device using an inexpensive clutch instead of an electromagnetic clutch.

[0004]

According to the present invention, there is provided a sheet feeding apparatus in which a sheet feeding roller and a driving roller are driven by a single motor. The paper feed gear is installed rotatably in
It said clutch plate to a rotating shaft installed movably and in non-rotatable axially, the paper feed gear side surface of the clutch plate, the circumferential
Direction and deeper along the forward direction of the feed gear.
The cam groove and the cam groove
Connected to the end and provided at the deeper end of the cam groove
A loop groove consisting of a return groove with the same depth as the upper part of the step
Provided in this groove, the depth of the deepest part of the cam groove
Also accommodates a ball with a long diameter
The clutch plate is biased toward the paper feed gear side, and
Through the reverse rotation of the feed gear by the reverse rotation of the above motor
The ball located above the notch crosses the step
When it falls from the return groove to the deepest part of the cam groove
Of the clutch plate approaching the paper feed gear side,
The above-described paper feed gear corresponds to the projection provided on the clutch plate.
In the forward rotation direction, and the return groove
The ball stored in the clutch plate causes the clutch plate to
When the projection is moved away from the paper feeding gear,
Cannot be engaged in the forward and reverse directions of the feed gear
The feeding gear is provided with a
When the ball is housed in the cam groove,
When the paper feed gear is reversed, the ball
Exits and reaches the return groove, after which the feed gear is rotated forward
And the ball rolls in the return groove and returns to above the step
And it is characterized in that the turned so that.

[0005]

According to the present invention, when a paper feed command is sent, the paper feed gear is once rotated backward by a predetermined angle and then forwardly rotated.
Then, the ball falls into the cam groove, the clutch plate and the projections of the paper feed gear engage, and the rotational force is transmitted to the paper feed roller.

When the leading edge of the sheet reaches the drive roller, the motor is stopped, and the motor is rotated in the reverse direction to rotate the sheet feeding gear by a predetermined angle. Then
The ball rolls in the cam groove and reaches the return groove. And
When the feed gear is rotated forward from here, the ball rolls in the return groove and returns to above the step, so that the engagement between the clutch plate and the projections of the feed gear is released, and the feed gear is It will spin idle. Therefore, the paper feed roller does not rotate.

[0007]

1 to 1 show an embodiment of a sheet feeding apparatus according to the present invention.
2 will be described. First, an outline of the sheet feeding device of the present invention will be described with reference to FIGS. The feed roller 1 and the drive roller 2 are connected to a motor 4 via an idle gear train 3 composed of gears 3a, 3b, 3c.
Reference numeral 0 denotes a structure for transmitting rotation to the paper feed roller 1 via the clutch 11. When a paper feed command is sent, the paper feed roller 1 is rotated by the operation of the clutch 11 to supply the paper 7. When the leading end of the paper 7 reaches the drive roller 2, the operation of the clutch 11 causes the paper feed gear 10 to idle. And then, the gear 2a
Only the drive roller 2 drives the sheet, and the drive roller 2 conveys the sheet. Therefore, the sheet 7 is not conveyed by the sheet feeding roller 1, and the second and subsequent sheets remain in the tray 8. The continuous feeding of the paper 7 is prevented.

Next, the structure of the clutch 11 of the sheet feeding device of the present invention will be described with reference to FIGS. In the figure, 1
Reference numeral 2 denotes a rotation shaft of the paper feed roller 1, and reference numeral 13 denotes a clutch plate.
The paper feed gear 10 is rotatably mounted on the rotary shaft 12, and the clutch plate 13 is assembled with the notch 12 a of the rotary shaft 12 engaged with the locking portion 13 b of the clutch plate 13. That is, the clutch plate 13 can move in the direction of the rotating shaft 12, but is prevented from rotating. A bush 14 is provided on the rotating shaft 12, and a spring 15 is provided between the bush 14 and the clutch plate 13 as a biasing means to urge the clutch plate 13 toward the paper feed gear 10. I have. Reference numeral 16 denotes a washer for locking the sheet feeding gear 10 and the bush 14 respectively.

Three cam grooves 17 extending in the circumferential direction are formed on the side surface of the clutch plate 13 on the side of the paper feed gear 10. In addition, return grooves 18 are connected to both ends of these cam grooves 17,
As shown in FIG. 5, loop-shaped grooves are respectively formed. As shown in FIG. 6, the cam groove 17 has a bottom surface 17a inclined so as to be deeper in the normal rotation direction (the direction of arrow A in FIG. 4) of the paper feed gear 10. Further, a step 19 is provided at the deeper end of the cam groove 17, and the return groove 18 is formed at the same depth as the upper step of the step 19. The balls 20 are accommodated in the respective cam grooves 17. The diameter of the ball 20 is slightly larger than the depth of the deepest portion of the cam groove 17. The feed gear 10 is provided with a pair of protrusions 21 that engage with protrusions 22 formed on the side surface on the clutch plate 13 side, and these protrusions 21 are arranged at two equally-divided positions in the circumferential direction. .

Next, the operation of the sheet feeding device of the present invention will be described with reference to FIGS. First, on the stairs before feeding,
As shown in FIG. 7, the ball 20 has the cam groove 17 and the return groove 18.
And the clutch plate 13 is
And the projection 2
2 is also disengaged from the projection 21 of the paper feed gear 10, and the motor 4 does not drive the paper feed roller 1.

When the paper feed command is sent, the motor 4 is rotated in the reverse direction, and the paper feed gear 10 is rotated in the reverse direction (the direction of arrow B in the figure) by a predetermined angle as shown in FIG. Then, the ball 20 drops into the cam groove 17 beyond the stepped portion 19. Then, the motor 4 is further rotated in the reverse direction, and the paper feed gear 10 is
Is rotated in the direction of the arrow of FIG.
Engages with the protrusion 22 of the clutch plate 13, the driving force of the motor 4 is transmitted to the rotating shaft 12, and the paper feed roller 1 rotates to start the conveyance of the paper 7. At this time, the ball 20 hits the step 19 and is prevented from advancing in the cam groove 17.

When the leading edge of the paper 7 reaches the drive roller 2,
The motor 4 is stopped to stop the rotation of the paper feed gear 10, and the paper feed gear 10 is rotated reversely by a predetermined angle as shown in FIG. Then, the ball 20 runs up the bottom surface 17a of the cam groove 17 and reaches the corner portion 18a of the return groove 18, so that the clutch plate 13 is separated from the paper feed gear 10. Then, as shown in FIG. 11, when the sheet feeding gear 10 is rotated forward, the ball 20 rolls in the return groove 18 and reaches the boundary with the cam groove 17 (returns to the position in FIG. 7). Therefore, the projection 21 of the sheet feeding gear 10 is disengaged from the projection 22 of the clutch plate 13, and the sheet feeding gear 10 idles. Therefore, the conveyance of the second and subsequent sheets 7 is not performed.

[0013]

As described above, the present invention has the following advantages. That is, a cam groove and a return groove are formed in a loop shape on the side surface of the clutch plate, and a ball is housed in the cam groove and the clutch plate is pressed against the side surface of the sheet feed gear. When the paper feed gear and the protrusions of the clutch plate are engaged with each other when the paper feed roller is rotated downward, the paper feed roller rotates, and the paper feed gear is reversely rotated by a predetermined angle from here, and then forwardly rotated. Since a clutch that moves through the cam groove and the return groove to a position above the step and disengages the projections is adopted, it is necessary to use expensive parts such as an electromagnetic clutch. And cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a side view of the sheet feeding device.

FIGS. 3A and 3B are enlarged views of a clutch installed in the sheet feeding device, wherein FIG. 3A is a front view and FIG.

FIG. 4 is an exploded perspective view of the clutch.

FIG. 5 is an enlarged view showing a cam groove and a return groove of the clutch plate of FIG. 4;

6 is a sectional view taken along line XX shown in FIG.

FIG. 7 is a view for explaining the operation of the clutch, and FIG.
Is a front view, and (b) is a side sectional view.

FIG. 8 is a view for explaining the operation of the clutch, and FIG.
Is a front view, and (b) is a side sectional view.

FIG. 9 is a view for explaining the operation of the clutch, and FIG.
Is a front view, and (b) is a side sectional view.

FIG. 10 is a view for explaining the operation of the clutch.
(A) is a front view, (b) is a side sectional view.

FIG. 11 is a diagram illustrating the operation of the clutch.
(A) is a front view, (b) is a side sectional view.

FIG. 12 is a plan view of a sheet feeding device showing a conventional example.

FIG. 13 is a side view showing the above conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper feed roller 2 drive roller 3 idle gear train 4 motor 7 paper 10 paper feed gear 11 clutch 12 rotating shaft 12a notch 13 clutch plate 13b locking portion 14 bush 15 spring 16 washer 17 cam groove (loop-shaped groove) 17a Bottom 18 Return groove (loop-shaped groove) 18a Corner 19 Step 20 Ball 21,22 Projection

Claims (1)

(57) [Claims] 1. A sheet feeding device in which a sheet feeding roller and a driving roller are driven by a single motor, wherein a sheet feeding gear is rotatably installed on a rotation shaft of the sheet feeding roller, the clutch plate is installed immovably freely and rotate in the axial direction to the shaft, the paper feed gear side surface of the clutch plate, in the circumferential direction extend and in the forward direction of the sheet feeding gear
A cam groove with a bottom surface that slopes deeper along
Connected to both ends of the cam groove, the deeper end of the cam groove
Return groove of the same depth as the upper part of the step provided in
Groove is provided, and this groove is formed at the deepest part of the cam groove.
Contains a ball with a diameter longer than the depth
At the same time, the clutch plate is urged toward the paper feed gear side,
Before feeding the paper , the reverse rotation of the feed gear caused by the reverse rotation of the motor
The ball located above the step is
From the return groove to the deepest part of the cam groove
When the clutch plate moves closer to the paper feed gear side
Therefore, the above-mentioned supply is provided to the projection provided on the clutch plate.
The paper gear can be engaged in the normal rotation direction, and
The ball is housed in the return groove and
When the plate is moved away from the feed gear,
Engage the protrusion in the forward and reverse directions of the feed gear.
The feed gear is provided with a projection
When the ball is accommodated in the cam groove,
When the paper gear is reversed, the ball comes out of the cam groove.
When the feed gear is rotated forward, the button
The roller rolls in the return groove and returns to above the step
Sheet feeding apparatus according to claim that it is earthenware pots.