JPH08282873A - Paper feeding device - Google Patents

Abstract

PURPOSE: To provide a paper feeding device in which lateral separating claws are vertically moved while keeping the same height without providing a cam and a clutch spring on both side, and a sheet makes contact with a paper feed roller in parallel. CONSTITUTION: This device has a cassette 1 for housing a plurality of recording sheets; a sheet pressing arm 27 arranged in the corner part of the cassette 1, laterally having separating claws 27a, and rotated around boss 1a arranged on both side surfaces of the cassette 1; a cam 7 arranged in a position making contact with a part of the sheet pressing arm 27; and a paper feed roller 5 fixed to the driving shaft of the cam 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device used in an electrophotographic apparatus or the like for feeding sheets stored in a cassette one by one.

[0002]

2. Description of the Related Art In a sheet feeding device used in an electrophotographic apparatus such as a printer, a copier, a facsimile, a sheet stored in a cassette has conventionally been used with a separating claw installed at a corner portion of the cassette. The method of separating the sheets one by one is widely used. On the other hand, in order to realize the downsizing and cost reduction of the apparatus, the configuration in which one roller serves both as a sheet feeding roller for feeding the sheet from the cassette and a conveying roller for feeding the fed sheet to the printing unit Has been incorporated. Such a conventional sheet feeding device will be described below with reference to the drawings.

FIG. 3 is a side sectional view of an electrophotographic apparatus having a conventional paper feeding device. In FIG. 3, 1 is a cassette for accommodating recording sheets 4, 1a is a boss as a fulcrum, 2 is a bottom plate for stacking sheets 4, 3 is a cassette spring for pressing the bottom plate 2 upward, and 5 is a rotation in the direction of arrow A. A sheet feeding roller for feeding the sheet 4 from the cassette 1, 6 is a separating claw for separating the sheets 4 fed by the sheet feeding roller 5 one by one, and 6a and 6b are sheets integrated with the separating claw 6. A pressing arm, 7 is a cam that rotates around a shaft 5a (see FIG. 5) as a fulcrum and pushes down the separation claw 6, 8 is a conveying roller that conveys the sheet 4 upward, 9 is an auxiliary roller that is pressed against the conveying roller 8, and 10 Is an auxiliary roller that is pressed against the paper feed roller 5, 11
Is a process unit, 12 is a photoconductor rotatably supported by a fixed shaft provided on the side wall of the process unit 11, 13 is a charger that charges the photoconductor 12 positively or negatively,
Reference numeral 14 is an exposure optical system for irradiating the photoconductor 12, reference numeral 15 is a developing roller which is rotatably supported on the side wall of the process unit 11 and conveys toner onto the photoconductor 12, and 16 is a process unit above the developing roller 15. A developing blade fixed to the side wall of 11 and in contact with the surface of the developing roller 15 via toner, 17 is rotatably supported by the side wall of the process unit 11, and supplies toner to the surface of the developing roller 15. A roller, 18 is rotatably supported on the side wall of the process unit 11, and is a transfer roller for transferring the toner adhering to the photoconductor 12 and developed to the sheet 4, and 19 is a cleaning blade for removing the residual toner on the photoconductor 12. , 20 are composed of a heat roller 21 having a heat source inside and a pressure roller 22, and the transfer roller 18 causes the sheet 4
A fixing device for fixing the composite image transferred thereon by pressure and heat, and 23 is a paper discharge tray for stacking the printed sheets 4.

The separating claw 6 is pushed down by the cam 7,
At the same time, the bottom plate 2 and the seat 4 are set by the cassette spring 3.
Since it is pressed upwards via the
When is rotated, the cam 7 repeats ascending and descending as the outer shape of the cam 7 changes. FIG. 3 shows a state in which the separation claw 6 is lowered and the sheet feeding roller 5 and the sheet 4 are separated from each other. Further, as shown in FIG. 3, the peripheral surface of the photoconductor 12 is indicated by an arrow B.
Charger 13, exposure optical system 14, developing roller 15, transfer roller 18, cleaning blade 1
9 are provided.

FIG. 4 is a side sectional view of a conventional paper feeding device in the electrophotographic apparatus shown in FIG. In FIG. 4, 1a
Is a boss, 5 is a sheet feeding roller, 6 is a separating claw, and 7 is a cam. These are the same as those in FIG. FIG. 4 shows that as the cam 7 rotates in the direction of arrow A, the separation claw 6 changes in accordance with the change in the outer shape of the cam 7.
Shows a state in which the sheet feeding roller 5 and the sheet 4 are in contact with each other by rotating around the boss 1a provided on the cassette 1 as a fulcrum.

FIG. 5 is a side sectional view of a conventional paper feeding device. In FIG. 5, 1 is a cassette, 2 is a bottom plate, 3 is a cassette spring, 4 is a sheet, 5 is a paper feed roller, 6 is a separating claw, and 7 is a cam. The description is omitted. Reference numeral 5a is a shaft for driving the paper feed roller 5 to rotate, 24 is a paper feed roller gear which is inserted into the D-cut portion of the shaft 5a of the paper feed roller 5 and rotates integrally with the paper feed roller 5, 25 is a boss outer periphery of the cam 7. A clutch spring fitted on the outer periphery of the boss of the paper feed roller gear 24, 26 has a swing piece 26a (see FIG. 6), and the swing piece 26a is the control pawl 2 of the clutch spring 25.
The solenoid 5a releases the connection of the feed roller gear 24 and the cam 7 in the rotational direction by stopping the rotation of 5a (see FIG. 6).

The operation of the electrophotographic apparatus having the conventional sheet feeding device configured as described above will be described below.

In FIG. 3, the sheets 4 stacked on the bottom plate 2 of the cassette 1 are delivered from the cassette 1 while being separated one by one at the separation claw 6 by the rotation of the sheet feeding roller 5 in the direction of arrow A. As the conveyance roller 8 and the paper feed roller 5 rotate, the conveyance roller 8 is conveyed to the contact point between the photoconductor 12 and the transfer roller 18. Here, since the sheet feeding roller 5 is pressed against the auxiliary roller 10, it also serves as a conveyance roller that conveys the sheet 4 to the contact point.

Next, the process of printing on the sheet 4 will be described. First, a high voltage is applied to the charger 13 connected to the high-voltage power supply, the photoconductor 12 is rotated in the direction of the arrow B to uniformly charge the surface of the photoconductor 12, and the surface of the photoconductor 12 is uniformly charged. Then, the exposure optical system 14 irradiates an exposure light beam of a laser beam according to image data to form an electrostatic latent image on the photoconductor 12. Next, the toner on the developing roller 15 supplied by the replenishing roller 17 is triboelectrically charged into a uniform thin layer state by the pressing force of the developing blade 16 and is conveyed onto the photoconductor 12. Further, the developing roller 1 having toner on its surface
By applying a negative potential to No. 5 and applying a negative charge to the toner in advance, the toner adheres only to the portion on the photoconductor 12 where the exposure light beam is irradiated and the charge is lost, and development is performed by a so-called negative-positive process. . The toner adhered to the photoconductor 12 and developed is fed by the feed roller 5 by applying a high voltage to the transfer roller 18, and then conveyed to the contact point between the developing roller 12 and the transfer roller 18. The image is transferred onto the surface of the sheet 4 by the transfer roller 18. The residual toner not transferred from the photoconductor 12 onto the surface of the sheet 4 is removed by the cleaning blade 19. Subsequently, the sheet 4 on which the toner image is transferred is sent to the fixing device 20, and is fixed by the heat of the heat roller 21 and the nip pressure of the pressure roller 22. The sheet 4 on which the toner image is fixed is discharged onto the discharge tray 23.

Next, the movement of the separating claw 6 at the time of feeding will be described. FIG. 3 shows a state at the time of standby, and at the time of standby, the separation claw 6
Is pushed down by the cam 7, and the sheet 4 is not in contact with the sheet feeding roller 5. When the paper is fed, the separation claw 6 is raised and lowered once by rotating the cam 7 once, and while the sheet 4 and the feed roller 5 are in contact with each other as shown in FIG. The sheet 4 is sent out. The rotation and stop of the cam 7 are controlled by turning on and off the solenoid voltage.

6A and 6B are operation explanatory views showing the solenoid operation. FIG. 6A is a sectional view taken along the line CC of FIG. 5 when the solenoid voltage is OFF (not applied), and FIG. 6B is the solenoid. FIG. 6 is a cross-sectional view taken along the line CC of FIG. 5 when the voltage is on (applied). In FIG. 6, reference numeral 24 is a paper feed roller gear, 25 is a clutch spring, and 26 is a solenoid. Since these are the same as those in FIG. 5, the same reference numerals are given and description thereof is omitted. 25a is a control pawl of the clutch spring 25, and 26a
Is a swinging piece of the solenoid 26, and 26b is an iron core of the solenoid 26.

In FIG. 6, when the solenoid voltage is off, the swinging piece 26a of the solenoid 26 is located away from the iron core 26b as shown in FIG. I'm hitting.
Therefore, even if the paper feed roller gear 24 rotates in the direction of arrow D, the clutch spring 25 remains stopped, and as a result, the cam 7 also stops. On the other hand, when the solenoid voltage is turned on, the swinging piece 26a of the solenoid 26 is attracted to the iron core 26b and separated from the control pawl 25a of the clutch spring 25, as shown in FIG. 6B. At this time, the clutch spring 25 moves the paper feed roller gear 24.
In the direction of arrow D, the inner diameter of the spring is reduced so that the boss of the feed roller gear 24 and the boss of the cam 7 are tightened. As a result, the clutch spring 25 and the cam 7 rotate together with the feed roller gear 24. To do.

As described above, when the solenoid voltage is turned on once, the cam 7 makes one rotation to feed one sheet 4 from the cassette 1. After that, when the solenoid voltage is turned off, the cam 7 becomes a clutch. Control claw 2 of spring 25
The sheet 5a stops after being rotated to a position where the sheet 5a abuts on the swing piece 26a of the solenoid 26, and the sheet 4 is separated from the sheet feeding roller 5. At this time, the sheet feeding roller 5 is continuously rotating and conveys the sheet 4 fed from the cassette 1 to the position of the transfer roller 18.

[0014]

However, in the above-mentioned conventional sheet feeding device, since the cam 7 pushes down only one separation pawl 6 as shown in FIG. 5, the left and right separation pawls 6 have different heights. In this case, the sheet 4 tilts and comes into contact with the sheet feeding roller 5, causing skew and jam of the sheet 4. Further, as a countermeasure against this, when the separating claws 6 on both sides are pushed down, However, there is a problem that a cam and a clutch spring are required.

The present invention solves the above-mentioned conventional problems. The left and right separation claws move up and down while maintaining the same height without providing cams and clutch springs on both sides, and the sheet is moved relative to the sheet feeding roller. It is an object of the present invention to provide a paper feeding device in which sheets are in parallel contact with each other.

[0016]

In order to achieve this object, a sheet feeding device according to claim 1 of the present invention comprises a cassette for storing a plurality of recording sheets, and a left and right side of the cassette. A paper pressing arm that has a separating claw on its center, and rotates around fulcrums arranged on both sides of the cassette; and a cam that is arranged at a position that abuts a part of the paper pressing arm.
And a paper feed roller fixed to the drive shaft of the cam.

[0017]

With this structure, since the left and right separation claws are integrated, the left and right separation claws move up and down while maintaining the same height as the cam that rotates around the shaft as a fulcrum is rotated. The paper feed roller contacts in parallel. Therefore, it is possible to prevent the sheet feeding roller from being unevenly contacted with the sheet, which causes skewing and jamming of the sheet.

[0018]

EXAMPLE 1 Example 1 of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a main part of a paper feeding device according to an embodiment of the present invention, and FIG. 2 is a front sectional view showing a paper feeding device according to an embodiment of the present invention.

1 and 2, 1 is a cassette, 1a
Is a boss as a fulcrum, 2 is a bottom plate, 3 is a cassette spring, 4 is a sheet, 5 is a paper feed roller, 7 is a cam, 24 is a paper feed roller gear, 25 is a clutch spring, and 26 is a solenoid. , Which is the same as that in FIG. 5, the same reference numerals are given and the description thereof is omitted. Reference numeral 27 denotes a paper pressing arm in which the left and right separation claws 27a are formed by one member and integrated, and the paper pressing arm 27 swings with the boss 1a provided in the cassette 1 as a fulcrum.

The operation of the sheet feeding device configured as described above will be described below. Here, description of sheet feeding operation and printing operation similar to those of the conventional sheet feeding apparatus and the electrophotographic apparatus having the conventional sheet feeding apparatus will be omitted, and only the points different from the conventional one will be described. In FIG. 2, in the standby state, the cam 7 pushes down the sheet pressing arm 27, and the integrated left and right separation claws 27a are lowered to the same height. At the time of paper feeding, the left and right separation claws 27a ascend while keeping the same height as the cam 7 rotates. While the left and right separation claws 27a are rising, the sheet 4 comes into contact with the sheet feeding roller 5 in parallel, and the sheet 4 is fed without causing skew and jam.

As described above, according to the present embodiment, the left and right separating claws 27a are integrated, so that the left and right separating claws 27a move up and down while keeping the same height as the cam 7 rotates, and at the time of sheet feeding. Since the sheet 4 and the sheet feeding roller 5 are in parallel contact with each other, it is possible to prevent skew and jam of the sheet 4 caused by partial contact of the sheet feeding roller 5 with the sheet 4. In this case, neither cam nor clutch spring is required on both sides.

[0023]

As described above, according to the present invention, a cassette for accommodating a plurality of recording sheets, a fulcrum arranged on the corners of the cassette, having separation claws on the left and right, and arranged on both side surfaces of the cassette. A paper pressing arm that rotates around the center of the paper, and a cam that is arranged at a position that abuts a part of the paper pressing arm,
By providing a paper feed roller fixed to the drive shaft of the cam, the left and right separation pawls are integrated, and the left and right separation pawls move up and down while maintaining the same height according to the rotation of the cam. Since the sheet feeding roller and the sheet feeding roller are in parallel contact with each other, it is possible to realize a sheet feeding device capable of preventing the sheet from skewing or jamming caused by one-sided contact of the sheet feeding roller without providing cams and clutch springs on both sides. be able to.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a front sectional view showing a sheet feeding device according to an embodiment of the present invention.

FIG. 3 is a side sectional view of an electrophotographic apparatus having a conventional paper feeding device.

FIG. 4 is a side sectional view of a conventional paper feeding device.

FIG. 5 is a front sectional view of a conventional paper feeding device.

FIG. 6 (a) C of FIG. 5 when the solenoid voltage is off.
-C line sectional view (b) CC line sectional view of FIG. 5 when the solenoid voltage is on

[Explanation of symbols]

 1 Cassette 1a Boss 2 Bottom Plate 3 Cassette Spring 4 Sheet 5 Paper Feed Roller 5a Shaft 7 Cam 24 Paper Feed Roller Gear 25 Clutch Spring 26 Solenoid 27 Paper Holding Arm 27a Separation Claw

Claims (1)

[Claims] 1. A cassette for accommodating a plurality of recording sheets, a paper feed roller located above the cassette and fixed to a drive shaft, and a cam arranged so as to abut on a part of a paper pressing arm. A sheet feeding device having: a sheet holding arm disposed at an end portion of the cassette, having left and right separation claws, and rotatable about a fulcrum disposed on both side surfaces of the cassette; Paper feeder.