JPH11199081A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uppermost paper out of paper stacked at a paper stacking part, feedable to a feed roller by disposing a paper sliding member of low frictional resistance opposedly to the paper stacking part, downstream of a contact point between the feed roller and a friction plate. SOLUTION: A paper guide 43 for guiding paper stored on a paper tray 8, to the feed roller 9 side is horizontally provided in an opposed position to the fed roller 9 of a printer body 1. A pair of protrusions 43a are provided at the feed roller 9 side tip of the paper guide 43. A lower end (feed roller side end) part of a case wall 44 of the printer body 1 is extended to provide a rib 44a, and a paper sliding sheet of small frictional resistance is stuck to the rib 44a so that the tip is positioned slightly above the paper contact part of the feed roller 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed roller for feeding paper to an image forming apparatus such as a copying machine, a printer, a printing machine, and the like, and a stack of paper provided inclined above the paper feed roller. The present invention relates to a sheet feeding device including a sheet stacking unit that performs a double feed of a sheet fed from a sheet stacking unit to a sheet feeding roller.

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Patent Application Laid-Open No. 5-294485, a paper feeder using a friction plate includes a paper feed roller for feeding paper to an image forming apparatus, and a paper feed roller. A paper tray, which is a paper stacking section for loading papers provided inclined upward, and a friction plate for preventing double feeding of the paper fed from the paper tray to the paper feed roller; Protrusions were formed on both sides on the upstream side.

An example in which this paper feeder is used in a laser printer will be described with reference to FIG.
Has a paper feeding unit (paper feeding device), an image forming unit, a laser scanning unit, and a fixing unit.

The paper supply section includes a paper tray 62 on which the paper P is stacked, a paper feed roller 63 for feeding the paper in the paper tray 62 one by one, and the paper P being fed by the paper feed roller 63. A friction plate 64 that applies a frictional force to the paper P so that the paper P is fed one by one when the paper P is fed, a paper detection actuator 65 that is activated by the contact of the leading end of the paper P, and a paper detection actuator that is activated by the paper detection actuator 65. A detection sensor for detecting paper feeding and a control circuit for controlling the above-described units are provided, and the paper P is prevented from entering the paper feeding roller on the upstream side of the friction plate 64 (the paper tray 62 side) to perform double feeding. Protrusion 6 to prevent
4a, the lower part of the side wall of the printer main body 61 facing the paper tray 62 is extended toward the paper feed roller 63 so that the paper P is guided to the paper feed roller 63.

[0005]

In the above-described paper feeding apparatus, when a large number of papers P are protruded from the friction plate toward the paper feeding roller side (upward) from the friction plate, the paper feeding roller is most likely Since the near sheet P is fed by the feed roller, the sheet P to be fed first is not the top sheet P but the sheet about 2 to 10 sheets lower. The protruding portion Y that protrudes above the friction plate between the friction plate and the friction plate penetrates, and a large load is applied to the paper feed roller (motor for driving the paper feed roller), resulting in an overload, thereby causing a failure and double feeding of paper. was there.

The paper feeding device of the present invention has been made in view of the above-mentioned problem, and has a frictional resistance that is opposed to the paper stacking portion on the paper feeding roller side upstream of the contact point between the paper feeding roller and the friction plate. It is an object of the present invention to arrange a small-sized paper sliding member so that the uppermost sheet among the sheets stacked on the sheet stacking section can be fed to the sheet feeding roller.

[0007]

In order to achieve the above-mentioned object, a paper feeder according to the present invention is provided with a paper feed roller for feeding paper to an image forming apparatus, and a paper feed roller inclined above the paper feed roller. A sheet stacking section for stacking the fed sheets, and a friction plate for preventing double feeding of the sheet fed from the sheet stacking section to the feed roller, and forming projections on both sides of the friction plate on the upstream side of the sheet feeding. A paper sliding member having a small frictional resistance is disposed on the paper feed roller side and upstream of a contact point between the paper feed roller and the friction plate so as to face the paper loading portion. Further, the paper sliding member is constituted by a driven roller.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser beam printer using a paper feeder according to the present invention will be described with reference to FIG. 1. The printer main body 1 includes a paper feed unit 2, an image forming unit 3, a laser scanning unit 4, and a fixing unit 5. It has. The paper feed unit 2 is an image forming unit 3
And the toner image is formed on the sheet P fed to the image forming unit 3. The paper P is discharged to a paper discharge section 7 by a paper discharge roller 6.

The paper supply unit 2 includes a paper tray 8 on which the paper P is stacked, a paper feed roller 9 for feeding the paper in the paper tray 8 one by one, and the paper P being fed by the paper feed roller 9. A friction plate 10 that applies a frictional force to the paper P so that the paper P is fed one by one when the paper P is fed, a paper detection actuator 11 that is operated by abutting the leading end of the paper P, and a paper that is activated by the paper detection actuator 11. And a control circuit 13 for controlling the above components.

The paper P placed on the paper tray 8 is
The sheet is fed one by one by the action of a paper feed roller 9 disposed below the paper tray 8, the friction plate 10, and a pressure spring 14 which constantly urges and presses the friction plate 10 against the paper feed roller 9,
The fed sheet P comes into contact with the sheet detection actuator 11, and the sheet detection actuator 11 is tilted. The detection sensor 12 detects the tilt of the sheet detection actuator 11, and outputs a sheet detection signal.
The control circuit 13 controls the image forming unit 3 and the laser scanning unit 4 based on the sheet detection signal.

The laser scanning unit 4 includes a laser light emitting diode (not shown) and reflection mirrors 16, 17, and 18 for reflecting laser light from the laser light emitting diode and irradiating the photosensitive member 15 of the image forming unit 3 with the laser light. Under the control of the control circuit 13, the photosensitive member 15 is selectively exposed to form an electrostatic latent image based on the image.

The image forming section 3 includes a photosensitive member 15, a charging device 19 for uniformly charging the surface of the photosensitive member 15, and a toner image by developing an electrostatic latent image formed on the photosensitive member 15. A developing device 20, a transfer roller 21 for transferring the toner image to the paper P, a cleaning device 22 for cleaning the remaining toner on the photoconductor 15, and a motor (not shown) for rotating the photoconductor 15 are provided.

Then, the surface charge of the photoconductor 15 uniformly charged in advance by the charging device 19 is discharged by irradiating the laser beam from the laser scanning unit 4 to form an electrostatic latent image on the photoconductor 15. . On the other hand, the toner for developing the electrostatic latent image is accumulated in the developing device 20, and the toner to which the charge is applied by moderate stirring in the developing device 20 adheres to the surface of the developing roller 20 a of the developing device 20. The developing bias voltage applied to the developing roller 20a and the photosensitive member 1
The toner image corresponding to the electrostatic latent image is formed on the photoreceptor 15 by the action of the electric field generated by the surface potential 5.

The paper P fed from the paper supply unit 2 to the image forming unit 3 is conveyed between the photoconductor 15 and the transfer roller 21, and the toner image on the photoconductor 15 is electrically attracted to the paper P. The toner remaining on the photoconductor 15 is transferred to the P and is cleaned and collected by the cleaning device 22.

Thereafter, the paper P on which the toner image has been transferred is conveyed to the fixing unit 5, where the toner on the paper P is heated and pressed by the fixing unit 5 to be melted and fixed on the paper P to form a solid image. P is transported from the fixing unit 5 by the transport roller 23 and is discharged via the discharge roller 6 to a discharge tray formed by the front wall surface of the printer serving as the discharge unit 7.

The photosensitive member 15 includes transmission gears 24, 25, 2
The rotation of the motor is transmitted via transmission gears 24, 25 and 26 and is driven to rotate clockwise while the transfer roller 21 is driven to rotate. On the other hand, the rotation of the motor is
The paper feed roller 9 is rotated via the clockwise rotation.

FIG. 2 is an exploded perspective view showing the assembly of the paper feed roller 9 and the spring clutch 31. The spring clutch 31 is formed integrally with a driving gear 32 to which a driving force is transmitted from a motor via a gear train. A cylindrical drive-side boss 33 and a driven-side boss 34 that rotates integrally with the rotating shaft 9 a to which the sheet feeding roller 9 is fixed are coaxially opposed to each other, and the outer periphery of the drive-side boss 33 and the driven-side boss 34 are arranged. , A coil spring 35 wound in a direction opposite to the rotation direction of the drive gear 32 and the drive side boss 34 is mounted on the coil spring 35, and a drive side sleeve 36 and a driven side sleeve 37 are further mounted on the coil spring 35.
Are externally fitted. The above coil spring 35
The drive side end 35a is locked in an engagement hole of the drive side sleeve 36, and the driven side end 35b is connected to the driven side sleeve 37.
Are locked in the engagement holes.

A rib 36b is formed at an end of the outer peripheral surface of the drive side sleeve 36 on the drive side.
A concave portion 36a is formed by cutting out a part of 6a. A plurality of teeth 37a are formed continuously on the outer peripheral surface of the driven side sleeve 37.

A rotary shaft 9a to which the paper feed roller 9 is fixed.
Supports the drive side boss 33 and the driven side boss 34. A protrusion 34 a is formed on the driven boss 34, and the protrusion 34 a engages with the concave portion 9 b of the paper feed roller 9. Due to this engagement, the driven boss 34 moves the feed roller 9 and the rotating shaft 9
It rotates together with a. On the other hand, the drive side boss 33 is
Rotate freely around a.

FIG. 3 is an external view showing the use state of the paper feed roller 9 and the spring clutch 31. The spring clutch 31 selectively transmits the rotation of the drive gear 32 in the direction of arrow A to the paper feed roller 9, The sheet feeding of the sheet P in the direction of arrow B on the lower surface of the sheet feeding roller 9 is controlled. The movable plate 3 is provided on the outer peripheral surface of the drive side sleeve 36 of the spring clutch 31.
8 is disposed so as to be able to freely contact and separate, and a lever 39 as an interlocking stopper is arranged so as to be able to freely contact and separate from the outer peripheral surface of the driven side spring clutch 37. The movable plate 38 moves up and down by turning on / off a solenoid (not shown). The lever 39 moves up and down in conjunction with the operation of the movable plate 38.

With the above configuration, the paper feed roller 9 to which the friction plate 10 is pressed is not only selectively driven, but also the paper P is held between the photosensitive member 15 and the transfer roller 21. After being turned, it is driven to rotate and the load can be kept low. Further, in the drive stop state, the sheet P can further be rotated in two directions independently of the rotating shaft 9a, and the processing of the sheet P having the jam and the replacement of the sheet P can be performed smoothly.

FIG. 4 is a cross-sectional view showing the details of the paper feeding section 2 of the first embodiment. The paper tray 8 of the paper feeding section 2 is detachably provided on the printer main body 1, and the paper tray 8 of the paper main body 1 is located on the printer main body 1 side. One end of a pressing plate 41 is rotatably supported by a rotating shaft 41a, and the pressing plate 41 is provided between the pressing plate 41 and the bottom plate 8a of the paper tray 8 by the feed roller 9 of the printer body 1.
A pressing spring 42 that urges the side is provided.

A paper guide 43 for guiding the paper P stored in the paper tray 8 toward the paper feed roller 9 is provided horizontally at a position facing the paper feed roller 9 of the printer body 1. A pair of protrusions 43a are provided at the end on the 9th side. The housing wall surface 4 of the printer body 1
The lower end (paper feed roller side end) of the paper feed roller 4 is provided with a rib 44a, and the rib 44a has a frictional resistance such that the tip is located slightly above a portion of the paper feed roller 9 where the paper P contacts. A paper sliding sheet 45 which is a small paper sliding member is stuck.

A lock mechanism (not shown) for locking the pressing plate 41 of the paper tray 8 is provided. The locking mechanism moves the pressing plate 41 in a direction to compress the pressing spring 42, and The pressing plate 41 is locked at a position corresponding to the number of sheets that can be stacked, and when the paper P is stacked on the paper tray 8, the lock is released, and the paper P can be fed, and the pressing spring 42 feeds the pressing plate 41. The sheet P is urged toward the roller 9 to press the sheet P against the sheet feeding roller 9.

At this time, the height of the pressing plate 41 corresponding to the number of sheets P that can be stacked is determined by the operability (easiness of stacking sheets).
In consideration of the above, it is best to secure a sufficient height, but in order to reduce the size of the apparatus, the height is suppressed to a level (1 to 3 mm) obtained by adding a margin to the number of stackable sheets.

Therefore, when stacking (inserting) a sheet bundle on the sheet tray 8, the uppermost sheet P of the sheet bundle comes into contact with the sheet sliding sheet 45, so that the uppermost sheet P and the sheet sliding sheet 45 Is small and the sheet bundle is smoothly stacked on the sheet tray 8, so that the uppermost sheet P is securely inserted to the lower portion (sheet feeding position) of the sheet feeding roller 9 without being interrupted by the frictional resistance. As a result, it is possible to prevent double feeding of the paper P.

Next, a second embodiment of the paper feeder used in the laser printer of the present invention will be described with reference to FIG. Note that the same parts as those in the first embodiment of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The sheet feeding device (sheet feeding section) according to the second embodiment is provided with a rib 44a extending from a lower end (end of the sheet feeding roller) of a housing wall surface 44 of the printer main body 1, and a sheet bundle is provided on the rib 44a. A driven roller 51 which is a sheet sliding member that rotates while contacting the uppermost sheet P when the sheet is loaded (inserted) into the sheet tray 8 is disposed.

Therefore, when stacking (inserting) a sheet bundle on the sheet tray 8, the uppermost sheet P of the sheet bundle comes into contact with the driven roller 51 and the driven roller 51 rotates.
Since the sheet bundle is smoothly stacked on the sheet tray 8 with almost no frictional resistance between the uppermost sheet P and the driven roller 51, the uppermost sheet P is not stagnated by the frictional resistance, and the sheet feed roller 9 Of the sheet P can be reliably inserted to the lower portion (sheet feeding position).

[0030]

According to a first aspect of the present invention, there is provided a sheet feeding device including: a sheet feeding roller for feeding a sheet to an image forming apparatus; and a sheet stacking section for tilting the sheet and loading the sheet. ,
A friction plate for preventing double feeding of the paper fed from the paper stacking unit to the paper feed roller, wherein projections are formed on both sides of the friction plate on the paper feed upstream side, and the paper feed roller on the paper feed roller side A sheet sliding member having a small frictional resistance is disposed on the upstream side of the contact point between the sheet stack and the friction plate so as to face the sheet stacking section. Therefore, when a sheet bundle is stacked (inserted) on the sheet stacking section, ,
Because the uppermost sheet of the sheet bundle abuts the paper slip member,
Since there is almost no frictional resistance between the uppermost sheet and the sheet sliding member and the sheet bundle is smoothly loaded on the sheet stacking section, the uppermost sheet is not stuck by the frictional resistance, and the lowermost portion of the sheet feeding roller ( Paper feed position) to prevent double feeding of paper, and no large load is applied to the drive unit that drives the paper feed roller.
The drive unit, for example, the motor can be reduced in size, and the housing can be simplified and reduced in weight.

Further, since the above-mentioned sheet sliding member is constituted by a driven roller, when a sheet bundle is loaded (inserted) on the sheet stacking portion, the uppermost sheet of the sheet bundle comes into contact with the driven roller and the sheet is moved. Since the driven roller rotates, there is almost no frictional resistance between the uppermost sheet and the driven roller, and the sheet bundle is smoothly loaded on the sheet stacking section, so that the uppermost sheet is not blocked by the frictional resistance. The sheet P is reliably inserted to the lower portion (sheet feeding position) of the sheet feeding roller, so that double feeding of the sheet P can be prevented, and more stable sheet feeding can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a laser printer using a sheet feeding device of the present invention.

FIG. 2 is an exploded perspective view of the paper feed roller of FIG.

FIG. 3 is a perspective view of the paper feed roller of FIG. 1;

FIG. 4 is a cross-sectional view illustrating Embodiment 1 of the sheet feeding device of the present invention.

FIG. 5 is an enlarged sectional view of FIG.

FIG. 6 is an enlarged sectional view showing a second embodiment of the sheet feeding device of the present invention.

FIG. 7 is a cross-sectional view of a laser printer using a conventional paper feeding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer main body 2 Paper feed part 8 Paper tray 9 Paper feed roller 41 Press plate 42 Press spring 43 Paper guide 43a Projection 44 Housing wall surface 44a Rib 45 Paper slip sheet 51 Follower roller

Claims (2)

[Claims] A sheet feed roller for feeding a sheet to an image forming apparatus; a sheet stacking section for tilting the sheet provided above the sheet feed roller; and a sheet feeding section for feeding the sheet from the sheet stacking section to the sheet feed roller. A friction plate for preventing double feeding of paper to be printed, forming projections on both sides of the friction plate on the upstream side of the paper feeding, and making a protrusion between the friction roller and the paper feeding roller on the paper feeding roller side. A sheet feeding device, wherein a sheet sliding member having a small frictional resistance is disposed on the upstream side so as to face the sheet stacking section. 2. The paper feeding device according to claim 1, wherein said paper sliding member is constituted by a driven roller.