KR101783948B1 - Paper feeding apparatus and image forming apparatus having the same - Google Patents

Abstract

The present invention provides an image forming apparatus in which an actuator or an upper paper feed frame on which various sensors are mounted is pivotally coupled to a paper feed tray rotatably mounted on the main body, thereby minimizing the size of the main body.

Description

TECHNICAL FIELD [0001] The present invention relates to a paper feeding device and an image forming apparatus having the same,

The present invention relates to a sheet feeding apparatus capable of reducing the size of an image forming apparatus and enabling miniaturization, and an image forming apparatus having the sheet feeding apparatus.

An image forming apparatus is an apparatus for forming an image on a print medium in accordance with an input image signal, such as a printer, a copying machine, a facsimile, and a multifunctional apparatus integrally implemented with these functions.

An image forming apparatus adopting the electrophotographic system includes a sheet feeding device in which a print medium is stored, an optical scanning device for scanning a beam in accordance with an image signal, a developing device for forming an image through a developer on a printing medium supplied from the sheet feeding device, A fixing device for fixing the developer on the printing medium, and a discharging device for discharging the printing medium on which the image formation has been completed to the outside.

The paper feeding device, the light scanning device, the developing device, the fixing device, and the paper discharging device are appropriately disposed according to the path through which the printing medium is conveyed in the main body.

On the other hand, the paper feeder includes a pick-up unit for picking up and transporting the print medium, an actuator for sensing the print medium loaded on the paper feed tray, an upper feeder for installing various sensors, and a pad or roller And the lower side paper feeding unit to be installed is in a state of being fixed to the main body.

One aspect of the present invention provides a paper feeding apparatus capable of minimizing the size of a main body and an image forming apparatus having the paper feeding apparatus.

To this end, the paper feeder according to an embodiment of the present invention includes a paper feed tray installed to be rotatable to a paper feed position and a standby position so as to be able to open and close a main body, a rotation shaft rotated by a drive source installed in the main body, And a pick-up unit that is rotated around the rotation shaft to pick up a print medium that is rotated in association with the upper paper feed frame and is loaded on the paper feed tray, .

Further, the rotation shaft may be installed inside the main body.

In the standby position, the upper paper feed frame may be located inside the main body, and at the paper feeding position, a portion of the upper paper feed frame may be located outside the main body.

The apparatus may further include a restraining device that restrains the paper feed tray and the upper paper feed frame from each other.

The restraining device may include a link member having both ends connected to the paper feed tray and the paper feed frame, respectively.

The pick-up unit may further include a feed roller coupled to the rotation shaft, a pick-up housing rotatably mounted on the rotation shaft, and a pick-up roller rotatably installed in the pick-up housing and rotated in association with the feed roller. .

In the standby position, the pick-up roller enters the inside of the main body, and in the paper feeding position, the pick-up roller may be positioned above the print medium loaded on the paper feeding tray.

In addition, the pick-up roller may be disposed at a first position at the standby position where the paper feed tray is closed, at a second position at the paper feed position where the paper feed tray is opened, and at a third position for picking up the print medium loaded on the paper feed tray Position.

In addition, an elastic member may be provided between the upper feeding frame and the pickup housing to elastically support the pickup housing in a direction in which the pickup roller rises.

The elastic member may include a coil spring whose one end is supported by the upper feed frame and the other end is supported by the pick-up housing.

The lower paper feed frame may further include a lower paper feed frame provided with a retard roller that is opposed to the paper feed roller and prevents a conveyance of the print medium conveyed by the pickup roller, .

The retard roller may include a torque limiter that rotates along the paper feed roller only when a force greater than a predetermined torque is applied to the retard roller.

The pick-up housing further includes a clutch unit for selectively receiving the rotational force of the rotation shaft. The clutch unit transmits the rotation force of the rotation shaft to the pickup housing when the rotation shaft rotates, rotates the pickup housing downward, When the pick-up roller contacts the print medium loaded on the paper feed tray and presses the pick-up housing, the rotational force of the rotation shaft can be prevented from being transmitted to the pick-up housing.

The clutch portion includes a clutch spring having a cylindrical portion of the bush fixed to the rotary shaft and a body portion which is pressed against the cylindrical portion of the flange provided in the pickup housing so as to have a pressing force and a sleeve surrounding the body portion, One end of the body is supported by the pick-up housing, and the other end of the body is supported by the sleeve.

A rotation shaft rotatable by a driving source provided in the main body; and a control unit for controlling the rotation of the main body of the paper feeding tray, And a pick-up unit which is rotated around the rotation axis to pick up a print medium which is rotated in association with the upper paper feed frame and is loaded on the paper feed tray can do.

The paper feed tray is rotatably disposed between a standby position for closing the main body and a paper feed position for feeding the paper tray by opening the main body. And at the paper feeding position, a part thereof may protrude to the outside of the main body.

The apparatus may further include a restraining device for restraining the paper feed tray and the upper paper feed frame from interlocking with the opening and closing operations of the paper feed tray to rotate the paper feed frame.

Further, an elastic member for elastically supporting the pick-up unit in a direction in which the pick-up unit is lifted may be provided between the upper paper feed frame and the pick-up unit.

The pickup unit may include a paper feed roller coupled to the rotation shaft, a pickup housing rotatably installed on the rotation shaft, and a paper feed roller rotatably installed in the pick-up housing to rotate in conjunction with the paper feed roller.

The pick-up roller may be located inside the main body when in the standby position, and the pick-up roller may be positioned above the print medium loaded on the paper feed tray when the paper is in the paper feeding position.

The apparatus may further include a retard roller disposed opposite to the paper feed roller and provided with a torque limiter for preventing a conveyance of the print medium picked up and conveyed by the pick-up roller.

And a body portion that is pressed against the cylindrical portion of the bush fixed to the rotary shaft and the cylindrical portion of the flange provided in the pickup housing to rotate the pickup housing in a direction in which the pickup roller descends during one- And a clutch unit having a sleeve which surrounds the body part. One end of the body part is supported by the pickup housing, and the other end of the body part is supported by the sleeve.

According to another aspect of the present invention, there is provided an image forming apparatus including: a main body having a rotation shaft rotatable by a driving source; a main body for moving between a standby position for closing the main body and a feeding position for opening the main body for feeding, A first roller coupled to the rotary shaft; a first roller disposed to be rotatable with the first roller so as to be rotatable with the first roller; A pick-up unit rotatably supporting the second roller and rotatably mounted on the rotation shaft, and a pick-up unit rotatably coupled to the paper feed tray, And a restraining unit for restraining the upper paper feed frame and the paper feed tray from each other, Frame is positioned inside said body, a portion of the upper feed frame when the feeding position is characterized in that the exposed outside the main body.

The second roller is disposed at a first position at the standby position and at a second position located at an upper portion of the print medium loaded on the paper feed tray at the paper feed position, And may be located in a third contact position.

The lower feed frame may further include a lower feed frame fixed to the main body, wherein the lower feed frame is provided with a retard roller which is positioned to face the first roller and prevents the conveyance of the print medium conveyed by the second roller, It can be installed as much as possible.

As described above, the paper feeding device and the image forming apparatus having the paper feeding device according to the embodiment of the present invention can minimize the size of the main body.

1 is a cross-sectional view showing a schematic structure of an image forming apparatus according to an embodiment of the present invention.
2 is a perspective view schematically showing a paper feeder according to an embodiment of the present invention.
3 is an exploded perspective view of a sheet feeding apparatus according to an embodiment of the present invention.
4 is an exploded perspective view showing the clutch unit of the pick-up unit according to the embodiment of the present invention.
5 is a cross-sectional view illustrating a state in which the sheet feeding apparatus is closed according to an embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating a state where the paper feeding device is opened according to the embodiment of the present invention.
7 is a cross-sectional view illustrating a state in which a pick-up roller of a paper feeder according to an embodiment of the present invention is operated.

Hereinafter, preferred embodiments of the image forming apparatus according to the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view showing a schematic structure of an image forming apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the image forming apparatus may include a main body 10 which forms an outer appearance and supports various components installed therein.

The main body 10 may be provided with a paper feeding device 100, a developing device 20, a light scanning device 30, a transfer device 40, a fixing device 50 and a paper discharging device 60.

The paper feeding device 100, the developing device 20, the transfer device 40, the fixing device 50 and the paper discharging device 60 provided in the main body 10 are arranged in a substantially horizontal printing And may be arranged along the horizontal direction so as to form the medium transport path S.

The paper feed unit 100 picks up the print medium P loaded in the paper feed unit 100 one by one by the pickup unit 90 and supplies the print medium P to the developing apparatus 20 side. A detailed description of the paper feeding device 100 will be described later.

The developing device 20 can be detachably mounted to the main body 10. [

The developing apparatus 20 is provided with a housing 25 in which main parts for performing a developing process such as a photosensitive medium 21, a developing roller 22, a supplying roller 23, and a charging roller 24, And can be mounted in a direction perpendicular to the bottom surface 13 of the main body 10 through an opening 15 formed in the upper portion of the main body 10. This is to reduce the size of the main body 10.

The opening 15 is opened and closed through a cover 17 rotatably coupled to the main body 10.

The light scanning device 30 irradiates light according to the image information of the output object to form an electrostatic latent image on the photosensitive medium 21. [

The optical scanning device 30 is disposed on the top of the developing device 20 vertically mounted on the main body 10 and is disposed in a direction perpendicular to the tangential direction of the photosensitive medium 21, As shown in FIG.

The optical scanning device 30 includes a light source 33 for irradiating a beam in accordance with an image signal, a light deflector 34 for deflecting the beam emitted from the light source 33, And a case 31 in which an F-theta lens 37 for scanning with the medium 21 is incorporated.

The light source 33 may include a laser diode for irradiating laser light and the light deflector 34 may include a polygon mirror 36 rotated by a driving motor 35.

The polygon mirror 36 has a plurality of reflecting surfaces on its side to deflect and scan the light incident from the light source 33. The deflected scanning light passes through the F- (Not shown).

A reflection mirror 38 for reflecting the beam scanned in the horizontal direction from the optical scanning device 30 in the vertical direction may be provided in front of the beam emerging port 32.

The beam reflected by the reflecting mirror 38 can be scanned in a direction perpendicular to the surface of the photosensitive medium 21 through an optical path provided in the developing apparatus 20. [

The transfer device 40 transfers the visible image formed on the photosensitive medium 21 to the print medium P. [

The transfer device 40 may include a transfer roller 41 that presses the print medium P toward the photosensitive medium 110 so that the visible image formed on the photosensitive medium 110 is transferred to the surface of the print medium P. [

The fixing device 50 applies heat and pressure to the print medium P to fix the developer image formed on the print medium P onto the print medium P.

The fixing device 50 may include a heating member 53 having a heating source 51 incorporated therein and a pressing roller 55 for pressing the printing medium P toward the heating member 53.

The heating member 53 may be formed of a roller type in which the heating source 51 is embedded or a belt type heated in the heating source 51.

The pressure roller 55 may be supported by an elastic member (not shown) so as to be in close contact with the heating member 53 and maintain a constant fixing pressure between the pressure roller 55 and the heating member 53.

The fixing device 50 applies heat and pressure to the visible image transferred to the printing medium P in the process of passing the printing medium P between the heating member 53 and the pressing roller 55, P).

The sheet discharging device 60 includes at least one sheet discharging roller 61 for discharging the printing medium P having passed through the fixing device 50 to the outside of the main body 10. [

FIG. 2 is a perspective view schematically showing a sheet feeding apparatus according to an embodiment of the present invention, FIG. 3 is an exploded perspective view of a sheet feeding apparatus according to an embodiment of the present invention, FIG. 4 is a cross- Fig.

1 to 4, a paper feeder 100 includes a paper feed tray 110 on which a print medium P is loaded, a paper feed tray 110 for picking up a print medium P loaded on the paper feed tray 110, And a pickup unit 90 for supplying the pick-up unit 70 to the pick-up unit 70.

The paper feed tray 110 may be a plate-shaped member having a predetermined area to cover a predetermined area on one side of the main body 10 and may be rotatably coupled with a hinge part 111 provided on the main body 10.

The paper feed tray 110 is provided in the main body 10 so as to be openable and closable. This paper feed tray 110 may be located at a first position (see FIG. 5) in the closed state in the main body 10 and a second position (see FIG. 6) in the opened state in the main body 10.

The first position means a standby position in which the paper feeding apparatus 100 is not used, and the second position means a paper feeding position in which the paper feeding apparatus 100 is operated.

The paper feed tray 110 is supported on the main body 10 through the link portion 114 (see FIG. 1), so that the paper feed tray 110 can be held in the standby state in the main body 10 at the second position.

The paper feed tray 110 may be provided with a guide member 113 for aligning the print medium P according to the width of the print medium P. [

The pick-up unit 90 includes a pick-up roller 120, a feed roller 130 for feeding the print medium P picked up by the pick-up roller 120 into the main body 10, And a retard roller 140 for preventing the pick-up of the print medium P from being conveyed.

The paper feeding roller 130 may be coupled to a rotating shaft 131 provided inside the main body 10.

The rotating shaft 131 can be rotated by a driving source (not shown) provided in the main body 10. [

That is, although not shown at the end of the rotating shaft 131, a gear for transmitting the rotational force of the driving source such as a motor to the rotating shaft 131 is connected, and a power switching such as an electromagnetic clutch for selectively connecting or disconnecting the gear and the rotating shaft 131 Unit is installed.

The pickup roller 120 may be disposed in parallel with the paper feed roller 130 at a predetermined interval.

The pickup roller 120 may be installed to be rotatable in the vertical direction about the rotary shaft 131 so as to pick up the print medium P loaded on the paper feed tray 110.

In addition, the pickup roller 120 may be installed to rotate by the rotational force transmitted to the paper feed roller 130 through the rotation shaft 131.

To this end, the pick-up unit 90 may include a pick-up housing 91 rotatably supported on the pick-up roller 120. The shaft 121 of the pickup roller 120 is rotatably coupled to the shaft hole 95 of the pickup housing 91.

The pickup housing 91 is formed so as to surround the pick-up roller 120 and the paper feed roller 130, and can be installed to be rotatable about the rotation axis 131.

The pickup housing 91 may be provided with a plurality of gear portions 92, 93 and 94 for transmitting the rotational force transmitted to the feeding roller 130 through the rotating shaft 131 to the pickup roller 120.

The gear portions 92,93 and 94 include a driving gear 92 coupled to the sheet feeding roller 130, a driven gear 94 coupled to the pickup roller 120, a driving gear 92 and a driven gear 94 And an intermediate gear 93 for connecting the intermediate gear 93 and the intermediate gear 93 to each other. The intermediate gear 93 can be rotatably installed in the pickup housing 91.

With this configuration, when the rotation shaft 131 rotates, the paper feed roller 130 and the pickup roller 120 rotate together.

A first one-way clutch 132 is provided at a portion where the rotation shaft 131 and the paper feed roller 130 are coupled to each other and a second one-way clutch 122 is provided at a portion where the driven gear 94 and the pickup roller 120 are connected. Can be installed. This is to prevent the rotational force from being transmitted to the rotating shaft 131 even if the feeding roller 130 and the pickup roller 120 rotate in the process of discharging the printing medium P after the pickup operation.

The pickup housing 91 may include a clutch unit 150 that rotates the pickup roller 120 to contact the print medium P loaded on the paper feed tray 110 when the rotation shaft 131 rotates.

The clutch unit 150 transmits a rotational force to the pickup housing 91 so as to rotate together with the rotation of the rotational shaft 131. When the rotational force in the opposite direction to the rotational force of the rotational shaft 131 is applied to the pickup housing 91, And a clutch spring 153 for interrupting a rotational force transmitted to the housing 91.

4, the clutch spring 153 has a cylindrical portion 154a of a bush 154 and a flange 151 protruding from one side of the pickup housing 91, which are integrally rotated with the rotation shaft 131 And both ends 153b and 153c of the body part 153a extend at different angles and are supported by the flange 151 and the sleeve 152. The body part 153a has a cylindrical shape.

The body portion 153a of the clutch spring 153 is selectively tightened to the cylindrical portion 154a of the bush 154 in accordance with the rotation direction of the pickup housing 91 and can be installed in a frictional contact or a releasable manner.

Accordingly, when the rotation shaft 131 rotates, the rotational force is transmitted to the pickup housing 91 through the clutch part 150, and the pickup housing 91 rotates in a direction in which the pickup roller 120 descends.

Thereafter, when the pickup roller 120 comes into contact with the print medium P loaded on the paper feed tray 110, the end portion 153c of the clutch spring 153 is brought into frictional contact with the cylindrical portion 154a of the bush 154 So that the rotation of the feed roller 130 is not transmitted to the pick-up housing 91 any longer and the rotation of the feed roller 130 is stopped by the rotation of the rotation shaft 131, And the pickup roller 120 are continuously rotated.

The upper feeding frame 160 may be provided on the upper part of the pick-up unit 90 and the lower feeding frame 170 may be provided below the pick-up unit 90.

The upper paper feed frame 160 is rotatably mounted on the rotary shaft 131 and the lower paper feed frame 170 is fixed to the main body 10.

The lower paper feed frame 170 is provided with a guide portion 171 for guiding the print medium P picked up by the pick-up roller 120 to the paper feed roller 130. The center portion of the guide portion 171 is in contact with the paper feed roller 130 A retard roller 140 for preventing the conveyance of the print medium P can be rotatably installed.

The retard roller 140 separates the remainder of the print medium P except for the first print medium when the print medium P picked up by the pickup roller 130 is two or more.

The retard roller 140 is rotated along the paper feed roller 1130 only when a force greater than a predetermined rotational force is applied to the retard roller 140. When the constant rotation force is not applied, 140 for stopping the rotation of the motor.

That is, when one sheet of printing medium P enters the nip NIP where the sheet feeding roller 130 and the retard roller 140 are in contact with each other, the retard roller 140 is provided with a torque The retard roller 140 is rotated in the direction of feeding the print medium P into the main body 10 along the paper feed roller 130. [

On the other hand, when two or more print media P enter the nip where the paper feed roller 130 and the retard roller 140 are in contact with each other, a torque lower than a set torque of the torque limiter 141 is applied to the retard roller 140 The retard roller 140 is stopped and the overlapped lower print medium P is prevented from being transferred into the main body 10. [

The upper paper feed frame 160 may be rotatably coupled to the rotary shaft 131 at an upper portion facing the lower paper feed frame 170.

Various sensors and actuators for detecting the state of the print medium P picked up and transported by the pick-up unit 90, which are not shown in the upper paper feed frame 160, may be combined.

The upper paper feed frame 160 can be rotated by interlocking with the opening and closing operations of the paper feed tray 110 through the restraining device 180 which confines the paper feed tray 110 and the upper paper feed frame 160.

The restraining device 180 is configured such that one end 182 is coupled to a hinge shaft 161 formed at one side of the upper feed frame 160 and the other end 183 is connected to a link guide 113 provided at one side of the feed tray 110 And a link member 181 inserted into the link member 181.

The other end 183 of the link member 181 may be provided with a protrusion 184 protruded to be inserted into the groove of the link guide 113 to be hooked.

The linking member 181 is described as an example of the restraining device 180. However, if the restraining device 180 is provided to interlock the rotation of the upper feeding frame 160 in conjunction with the rotation of the feeding tray 110, And the like.

An elastic member 190 may be provided between the upper paper feed frame 160 and the pickup housing 91 to elastically support the pickup housing 91 in a direction in which the pickup roller 120 is lifted.

Hereinafter, operations and effects of the sheet feeding apparatus according to the embodiment of the present invention will be described.

FIG. 5 is a cross-sectional view illustrating a state in which the sheet feeding apparatus is closed according to an embodiment of the present invention, FIG. 6 is a sectional view showing a state in which the sheet feeding apparatus is opened according to an embodiment of the present invention, Sectional view showing a state in which the pickup roller of the paper feeding device according to the example is operated.

When the image forming apparatus is not used, the paper feed tray 110 of this embodiment is coupled to the main body 10 to form one surface of the main body 10 as shown in FIG. This is to reduce the size of the main body 10 by the paper feed tray 110 when the image forming apparatus is not used.

 In this case, the upper paper feed frame 160 and the pick-up unit 90 are accommodated in the main body 10 while being coupled to the rotation shaft 131 installed in the main body 10.

6, when the paper feed tray 110 is rotated for the printing operation, the upper paper feed frame 160 is held in the paper feed tray 110 by the restricting device 180, (110).

At this time, the leading end portion 163 of the upper paper feed frame 160 is protruded outside the main body 10 by a predetermined distance L, and the pickup roller 120 is also protruded to the outside of the main body 10, 110).

The distance L where the upper paper feed frame 160 protrudes from the main body 10 occupies an unnecessary space when the existing upper paper feed frame 160 is in a fixed state, As shown in Fig.

However, since the upper paper feed frame 160 of the present embodiment is in a state of being housed inside the main body 10 as shown in FIG. 5 without performing the printing operation, the unnecessary space is reduced, The size can be reduced.

Thereafter, the printing medium P is loaded on the paper feed tray 110, and a printing operation is performed. In this case, when the rotary shaft 131 is rotated by the driving unit, the rotational force of the rotary shaft 131 is transmitted to the pickup housing 91 through the clutch unit 150, and the pickup housing 91 is rotated about the rotary shaft 131 And rotates until the pickup roller 120 comes into contact with the print medium P stacked on the uppermost portion of the paper feed frame 110.

When the pickup roller 120 comes into contact with the print medium P, the rotation shaft 131 is continuously rotated by the operation of the clutch unit 150, but the rotational force is not transmitted to the pickup housing 91, And the paper feed roller 130 are rotated.

The pickup roller 120 applies a frictional force to the printing medium P to pick up the printing medium P one by one and feeds the printing medium P to the feeding roller 130. [

Then, when the printing operation is terminated, the pickup housing 91 is rotated in the upward direction by the restoring force of the elastic member 190.

The paper feed unit 100 of this embodiment is provided so that the pickup roller 120 applies a pressing force to the print medium P loaded on the paper feed tray 110, The pick-up roller 120 can pick up the printing medium P by applying a predetermined pressing force to the printing medium P irrespective of the amount of the printing medium P.

That is, when the pressing force for pressing the pickup roller 120 against the printing medium P is applied by moving the paper feeding tray 110 up and down, the pressing force difference corresponding to the amount of the printing medium P loaded on the paper feeding tray 110 The sheet feeding apparatus 100 of the present embodiment is provided with a pickup roller 120 which is provided so as to apply a pressing force to the print medium P so that the print medium P loaded on the paper feed tray 110 The reliability of the paper feeding can be improved regardless of the amount of the paper P. [

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

10: main body, 20: developing device,
30: optical scanning device, 40: transferring device,
50: fixing device, 60:
90: pick-up unit, 100: paper feeder,
110: paper feed tray, 120: pickup roller,
130: Feed roller, 140: Retard roller,
150: clutch portion, 160: upper feed frame,
170: lower feeding frame, 180: restraining device,
190: Elastic member.

Claims (18)

A paper feed tray installed in the main body of the image forming apparatus and capable of rotating at a paper feeding position and a standby position;
A rotating shaft rotated by a driving source provided in the main body;
And a pickup roller having a pick-up roller and a feed roller coupled to the rotary shaft,
The pick-
When the paper feed tray is in the standby position, the pick-up unit is located at a first position disposed in the main body,
Wherein the pick-up unit is configured to move the pick-up roller from a second position where the pick-up roller is spaced apart from the print medium on the feed tray when the feed tray is at the feed position, To a third position in contact with the print medium on the paper feed tray for picking up,
Wherein the pick-up unit includes a clutch portion for selectively receiving a rotational force of the rotation shaft,
Wherein the clutch portion includes a clutch spring having a cylindrical portion of the bush fixed to the rotation shaft and a body portion which is pressed against the cylindrical portion of the flange provided in the pickup unit so as to have a pressing force and a sleeve surrounding the body portion, Wherein the end portion is supported by the pick-up unit, and the other end portion of the body portion is supported by the sleeve. The method according to claim 1,
The pick-
And an elastic member elastically biasing the pickup unit in an ascending direction,
Wherein the elastic member applies an elastic force to the pick-up unit so that the pick-up unit moves from the third position to the second position. The method according to claim 1,
Wherein the pick-up unit is located in the main body when the paper feed tray is in the standby position,
Wherein the pick-up unit is partially located outside the main body when the feed tray is at the feed position. The method according to claim 1,
And a lower paper feed frame fixed to the main body,
Wherein the lower paper feed frame is rotatably provided with a retard roller which is positioned opposite to the paper feed roller and prevents the paper conveyed by the pick-up roller from being conveyed. 5. The method of claim 4,
Wherein the retard roller includes a torque limiter for rotating the retard roller along the paper feed roller only when a force greater than a predetermined torque is applied to the retard roller. The method according to claim 1,
Wherein the clutch unit transmits the rotation force of the rotation shaft to the pickup unit when the rotation shaft rotates, rotates the pickup unit downward, and when the pickup roller contacts the print medium loaded on the paper feed tray, And stops transmission to the pick-up unit. The method according to claim 6,
Wherein the body portion of the clutch spring is selectively fastened to the cylindrical portion of the bushing along the rotational direction of the pick-up unit so as to be able to be frictionally engaged or disengaged with the cylindrical portion of the bush. The method according to claim 6,
Wherein the feed roller and the pick-up roller continue to rotate after the pick-up roller contacts the uppermost end of the loaded print medium of the feed tray. The method according to claim 1,
Wherein the pick-up unit further includes a plurality of gears for transmitting rotational force transmitted to the feeding roller through the rotation shaft to the pick-up roller,
The plurality of gears
A driving gear coupled to the paper feed roller;
A driven gear coupled to the pickup roller;
And an intermediate gear connecting the drive gear and the driven gear. The method of claim 3,
Wherein the pick-up roller protrudes from the main body at a predetermined distance outward. 10. The method of claim 9,
The pick-up unit includes: a first one-way clutch installed at a portion where the rotation shaft and the paper feed roller are coupled;
And a second one-way clutch installed at a portion where the driven gear and the pickup roller are connected so as not to transmit a rotational force to the rotational shaft when the pickup roller is rotated while the picked-up printing medium is discharged. The method according to claim 1,
Wherein the rotation shaft is installed inside the main body. The method according to claim 1,
Wherein the paper feed tray moves from the paper feeding position to the standby position and presses the pick-up unit such that the pick-up unit moves from the second position to the first position. 13. The method of claim 12,
Further comprising: a link member, one end of which is coupled to the paper feed tray and the other end of which is coupled to the pick-up unit so as to bind the paper feed tray and the pick-up unit. The method according to claim 1,
The pick-
And a pickup housing rotatably installed on the rotary shaft,
Wherein the paper feed roller is coupled to the rotation shaft, and the pick-up roller is rotatably installed in the pick-up housing and rotates in conjunction with the paper feed roller. The method according to claim 1,
Wherein the pick-up roller enters the inside of the main body at the standby position, and the pick-up roller is positioned above the print medium loaded on the feed tray at the feed position. 3. The method of claim 2,
And an upper feed frame rotatable about the rotation axis in association with opening and closing operations of the feed tray,
The elastic member
Wherein one end is supported by the upper paper feed frame and the other end is supported by the pick-up unit to apply an elastic force to the pick-up unit. A main body;
A paper feed tray rotatably installed in the main body and movable between a standby position for closing the main body and a paper feeding position for opening the main body for paper feeding;
A rotating shaft rotated by a driving source provided in the main body;
An upper feed frame rotatable about the rotation axis in association with an opening / closing operation of the feed tray;
And a pickup unit rotated in association with the upper paper feed frame and rotated around the rotation axis to pick up a print medium loaded on the paper feed tray,
Wherein the upper feeding frame is positioned inside the main body when the feeding position is in the standby position and a part of the upper feeding frame is exposed to the outside of the main body when the feeding position,
Wherein the pick-up unit includes a clutch portion for selectively receiving a rotational force of the rotation shaft,
Wherein the clutch portion includes a clutch spring having a cylindrical portion of the bush fixed to the rotation shaft and a body portion which is pressed against the cylindrical portion of the flange provided in the pickup unit so as to have a pressing force and a sleeve surrounding the body portion, Wherein the end portion is supported by the pick-up unit, and the other end portion of the body portion is supported by the sleeve.

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