Roller separation device and image forming apparatus using the same

An image forming apparatus and roller separation device are provided. The image forming apparatus including a main body having a print unit, a first paper feeding unit containing print paper and insertable in or pullable from the main body, a feed roller in the main body feeding the print paper from the first paper feeding unit to the print unit and comprising a driven roller contacting a driving roller, an elastic member applying an elastic force to the driven roller in a direction to contact the driving roller, a handle member in the main body movable to a first position and a second position, and a separation member connected to the handle member and switched to a normal position separated from the driven roller and a separation position separating the driven roller from the driving roller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to, and claims the priority benefit of, Korean Patent Application No. 10-2014-0091318, filed on Jul. 18, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

One or more embodiments of the present inventive concept relate to a roller separation device that may remove a pressing force of a roller for transferring sheets of paper, and an image forming apparatus using the roller separation device.

2. Description of the Related Art

Image forming apparatuses such as printers, copiers, etc. include a print unit for printing an image onto a sheet of paper, a paper feeding unit for supplying a large amount of paper, and a paper transfer unit for supplying sheets of paper from the paper feeding unit to the print unit. The paper transfer unit transfers sheets of paper by using pairs of transfer rollers pressed against each other.

Design of the paper transfer unit takes into consideration many design factors to prevent a paper jam in a process of transferring the paper. However, in spite of such design, a paper jam may occur due to various factors.

When a paper jam occurs, it may be difficult to remove jammed paper because the pair of transfer rollers may be connected to a motor for driving by using a power connection mechanism such as gears. If the jammed paper is forcibly removed, more serious problems may occur as the jammed paper may be torn. In other words, for example, the transfer roller pair may be damaged or the power connection mechanism may be damaged.

When a paper jam occurs, an attempt to remove the jam may be to disconnect the transfer roller pair and the motor to have the transfer roller pair enter an idle state. In this case, an electronic clutch may be required and thus the image forming apparatus may be complicated and expensive.

Another way to attempt to remove the jam may be to remove the pressing force of the transfer roller pair in engagement with an opening operation of a cover that opens a part of the image forming apparatus. In this case, however, since the cover may likely form a part of a paper transfer path, if the cover is connected to an apparatus that removes the pressing force of the transfer roller pair, positional stability of the cover may be degraded and thus the possibility of a paper jam on the paper transfer path may increase.

SUMMARY

One or more embodiments of the present inventive concept include a roller separation device that separates rollers from each other to facilitate removal of jammed paper when a paper jam occurs, and an image forming apparatus using the roller separation device.

According to one or more embodiments of the present inventive concept, an image forming apparatus includes a main body having a print unit, a first paper feeding unit containing a print paper and being insertable in or pullable from the main body, a feed roller provided in the main body and feeding the print paper picked from the first paper feeding unit to the print unit, the feed roller comprising a driven roller and a driving roller contacting each other, an elastic member applying an elastic force to the driven roller in a direction to contact the driving roller, a handle member provided in the main body to be movable to a first position and a second position, and a separation member connected to the handle member and switched to a normal position separated from the driven roller and a separation position to separating the driven roller from the driving roller by pulling the driven roller as the handle member moves to the first position and the second position, respectively.

The handle member may be provided in the main body to be slidable to the first position and the second position, and the separation member may be provided in the main body to be pivotable to the separation position and the normal position.

The separation member may include a pivot shaft, a pull portion to contact the rotation shaft and separate the driven roller from the driving roller as the separation member pivots from the normal position to the separation position, and an accommodation portion on which a rotation shaft of the driven roller is accommodated at the separation position.

The pull portion may include a first end portion and a second end portion having a pivot radius from the pivot shaft that is smaller than that of the first end portion, and a boundary portion having a pivot radius from the pivot shaft that is larger than that of the second end portion may be provided between the pull portion and the accommodation portion.

The pivot shaft of the separation member may be located around a line connecting centers of the driven roller and the driving roller.

An acting line of the elastic force of the elastic member and the pivot shaft may be located on the line.

When the separation member pivots from the normal position to the separation position, an angle between the pull portion and a line perpendicular to a line connecting centers of the driven roller and the driving roller may be equal to or less than 45°.

The image forming apparatus may include a return spring that applies an elastic force to the separation member in a direction in which the separation member is maintained at the normal position.

The image forming apparatus may include a first stopper provided on the separation member, and an excessive rotation prevention portion provided in the main body and contacted by the first stopper when the separation member is located at the separation position.

The image forming apparatus may include a second stopper provided on the handle member, and a movement prevention portion provided in the main body and contacted by the second stopper when the separation member is located at the normal position.

The handle member may be moved from the second position to the first position by an operation of inserting the first paper feeding unit into the main body, and a pressing portion pushing the handle member located at the second position toward the first position when the first paper feed unit is inserted into the main body may be provided on the first paper feeding unit.

A grip portion may be provided on the handle member, the pressing portion may cover the grip portion in a state in which the first paper feeding unit is inserted in the main body, and the grip portion may be exposed to the outside when the first paper feeding unit is pulled from the main body.

The handle member may be moved to the first position and the second position according to the inserting and pulling operations of the first paper feeding unit.

The handle member may pivot to the first position and the second position.

The handle member may be integrally formed with the separation member.

According to one or more embodiments of the present inventive concept, a roller separation device for separating a driven roller from a driving roller includes a holder supporting the driven roller, an elastic member pressing the driven roller in a direction in which the driven roller contacts the driving roller, a handle member supported on the holder to be slidable to a first position and a second position, and a separation member connected to the handle member and supported on the holder to pivot to a normal position separated from the driven roller and a separation position to separate the driven roller from the driving roller by pulling the driven roller as the handle member moves to the first position and the second position.

The separation member may include a pivot shaft, a pull portion to contact the rotation shaft and separate the driven roller from the driving roller as the separation member pivots from the normal position to the separation position, and an accommodation portion on which a rotation shaft of the driven roller is accommodated at the separation position, the pull portion may include a first end portion and a second end portion having a pivot radius from the pivot shaft that is smaller than that of the first end portion, and a boundary portion having a pivot radius from the pivot shaft that is larger than that of the second end portion may be provided between the pull portion and the accommodation portion.

The pivot shaft of the separation member may be located around a line connecting centers of the driven roller and the driving roller.

The roller separation device may include a return spring that applies an elastic force to the separation member in a direction in which the separation member is maintained at the normal position.

The roller separation device may include a first stopper provided on the separation member, an excessive rotation prevention portion provided on the holder and contacted by the first stopper when the separation member is located at the separation position, a second stopper provided on the handle member, and a movement prevention portion provided in the holder and contacted by the second stopper when the separation member is located at the normal position.

DETAILED DESCRIPTION

FIG. 1illustrates a structure of an image forming apparatus according to an exemplary embodiment.

Referring toFIG. 1, the image forming apparatus of an exemplary embodiment may include an image forming apparatus main body1and a paper feeding cassette (first paper feeding unit)2containing sheets of paper (recording medium) P. The image forming apparatus main body1includes a print unit3to print an image on the paper P supplied from the paper feeding cassette2. The paper feeding cassette2may be detachably provided in the image forming apparatus main body1to load the paper P. For example, the paper feeding cassette2may be installed in the image forming apparatus main body1to be slidable in a direction indicated by arrows A1and A2. As the paper feeding cassette2slides in a direction indicated by an arrow A2, the paper feeding cassette2may be pulled from the image forming apparatus main body1to be separated, e.g., completely separated from the image forming apparatus main body1.

The print unit3may print an image on the paper P by using a variety of printing methods such as an electrophotographic method, an inkjet method, a thermal transfer method, etc. The print unit3of an exemplary embodiment prints an image on the paper P. An example of the print unit3that uses a monochromic electrophotographic method is described.

The print unit3may include a developing unit10to form a toner image corresponding to image information. The developing unit10may be detachable from the image forming apparatus main body1and may be replaced when a toner contained therein is completely consumed.

A photoconductive drum11, as an example of a photoconductor having a surface on which an electrostatic latent image is formed, may include a conductive metal pipe and a photoconductive layer formed on an outer circumference of the conductive metal pipe. Although it is not illustrated inFIG. 1, a photoconductive belt may be used instead of the photoconductive drum11.

A charge roller13is an example of a charger that charges the photoconductive drum11to have a uniform surface electric potential. A charge brush, a corona charger, etc. may be used instead of the charge roller13. A cleaning roller14removes foreign materials adhering on a surface of the charge roller13. Although it is not illustrated, a cleaning unit for removing the toner and foreign materials remaining on the surface of the photoconductive drum11after a transfer process described later, may be provided. For example, a cleaning blade contacting the surface of the photoconductive drum11, a rotary brush for rotating and removing the foreign materials from the surface of the photoconductive drum11, etc. may be used as the cleaning unit.

A developing roller12may develop the electrostatic latent image formed on the photoconductive drum11into a visible toner image by providing the toner accommodated in a toner accommodation unit10-1to the electrostatic latent image. A developing bias voltage to supply the toner to the photoconductive drum11may be applied to the developing roller12. A supply roller15supplies the toner of the toner accommodation unit10-1the developing roller12. A supply bias voltage may be applied to the supply roller15.

A development method includes a one-component development method using a toner and a two-component development method using a toner and a carrier. The one-component development method may be divided into a contact development method in which the developing roller12and the photoconductive drum11rotate in contact with each other and a non-contact development method in which the developing roller12and the photoconductive drum11are separated from each other by about tens to hundreds of microns.

When the two-component development method is used, the developing roller12is separated from the photoconductive drum11by about tens to hundreds of microns. Although it is not illustrated, the developing roller12may have a shape that a magnetic roller is arranged in a hollow cylindrical sleeve. The toner is attached on a surface of a magnetic carrier. The magnetic carrier may be attached on a surface of the developing roller12and carried to a development area where the photoconductive drum11and the developing roller12face each other. The toner may be supplied to the photoconductive drum11by a development bias voltage applied between the developing roller12and the photoconductive drum11and thus the electrostatic latent image formed on the surface of the photoconductive drum11is developed into a visible toner image.

The print unit3of an exemplary embodiment employs a one-component contact development method. Although it is not illustrated, a transfer member for transferring the toner of the toner accommodation unit10-1toward the supply roller15may be arranged in the developing unit10. The transfer member may have a variety of shapes such as a paddle, an auger, etc. A restriction member (not shown) for restricting an amount of the toner supplied to the development area between the photoconductive drum11and the developing roller12by the developing roller12may be provided in the developing unit10. The restriction member may be, for example, a doctor blade that elastically contacts the surface of the developing roller12.

An exposure unit20forms the electrostatic latent image on the photoconductive drum11by irradiating light modulated corresponding to image information toward the photoconductive drum11. A laser scanning unit (LSU) using a laser diode as a light source, a light emitting diode (LED) exposure unit using an LED as a light source, etc. may be used as the exposure unit20.

A transfer roller30is an example of a transfer unit that transfers a toner image from the photoconductive drum11to the paper P. A transfer bias voltage to transfer the toner image to the paper P may be applied to the transfer roller30. A corona transfer unit or a pin scorotron type transfer unit may be used instead of the transfer roller30.

The paper P may be picked up, for example, one by one by a pickup roller21from the paper feeding cassette2and is transferred to an area where the photoconductive drum11and the transfer roller30face each other.

A fuser40fixes the toner image on the paper P by applying heat and pressure to the image on the paper P. The paper P that has passed through the fuser40is ejected to an exit tray5.

According to an exemplary embodiment, the exposure unit20forms the electrostatic latent image by scanning a light beam modulated corresponding to the image information onto the photoconductive drum11. The developing roller12forms the visible toner image on the surface of by the photoconductive drum11by supplying the toner to the electrostatic latent image. The paper P loaded in the paper feeding cassette2may be transferred to the area where the photoconductive drum11and the transfer roller30face each other. The toner image may be transferred to the paper P from the photoconductive drum11by the transfer bias voltage applied to the transfer roller30. When the paper P passes through the fuser40, the toner image may be fixed on the paper P by heat and pressure. The paper P with the completed fixed image may be ejected to the exit tray5.

The paper P picked up from the paper feeding cassette2may be transferred along a print path6, and the print unit3prints an image on the paper P. A plurality of paper transfer rollers to transfer the paper P may be arranged along the print path6. For example, the paper P picked up from the paper feeding cassette2by the pickup roller21may be supplied to the print path6by a feed roller110. Referring toFIG. 1, the paper feeding cassette2is connected to the print path6by the paper feed path8. The paper P picked up from the paper feeding cassette2is supplied to the print path6after passing through the paper feed path8. The feed roller110may be arranged along the paper feed path8. A registration roller61may be arranged at an upstream side of the area (transfer area) where the photoconductive drum11and the transfer roller30face each other. The registration roller61acts as a reference roller for paper transfer. A leading end of the paper P supplied from the paper feeding cassette2may be registered by the registration roller61. The registration roller61transfers the paper P that is registered, in time to when a leading end of the toner image formed on the photoconductive drum11arrives at the transfer area. The paper P that has passed through the fuser40may be transferred toward an exit roller63by a transfer roller62.

A reverse path7for duplex printing may be provided in the image forming apparatus main body1. The reverse path7is a path for supplying the paper P back to the print path6by flipping the paper P having an image printed on one surface of which while passing through the print path6. A plurality of transfer rollers71to transfer the paper P may be arranged on the reverse path7. The exit roller63may be reversely rotated in a state in which a trailing end of the paper P is held by the exit roller63before the paper P having passed through the print path6is completely ejected to the exit tray5. The paper P is transferred along the reverse path7and supplied back to the print path6. The paper P that is reversed passes through the transfer area with a rear surface of the paper P facing the photoconductive drum11. An image may be printed on the rear surface, and the paper P passes through the fuser40and may be ejected by the exit roller63to the exit tray5.

A multipurpose tray (second paper feeding unit)4may be used to supply sheets of paper P1having various regular/irregular sizes to the print unit3and may be arranged at a downstream side of the feed roller110. The paper P1supplied by the multipurpose tray4may be supplied to the print path6without passing through the feed roller110.

FIG. 2is a schematic view of a paper transfer path of a portion B ofFIG. 1. Referring toFIG. 2, the paper feeding cassette2may be arranged under the print unit3. To restrict an increase in the height of the image forming apparatus, the paper feed path8may be bent, e.g., sharply bent in an almost “C” shape and thus a paper jam may be highly likely to occur in the paper feed path8. Even when a paper jam occurs in the print path6, a part of the paper P may exist on the paper feed path8. The feed roller110may include a pair of rollers111and112pressed against each other. The roller111may be a driving roller and the roller112may be a driven roller. An elastic member113presses the driven roller112toward the driving roller111. To easily remove a jammed paper, the driven roller112may be separated from the driving roller111by moving the driven roller112in a direction opposite to a direction in which an elastic force of the elastic member113may be applied. A roller separation device for separating the driven roller112from the driving roller111may be provided in the image forming apparatus of an exemplary embodiment.

FIG. 3is an exploded perspective view of a roller separation device according to an exemplary embodiment.FIGS. 4 and 5are cross-sectional views of an exemplary roller separation device ofFIG. 3.

Referring toFIGS. 3 to 5, the driven roller112, a separation member140, a handle member130, and a holder120supporting these elements are illustrated. The driven roller112may be rotatably supported on the holder120. The driven roller112supported on the holder120may move in a direction to contact/be separated from the driving roller111. The elastic member113applies to the driven roller112an elastic force in a direction to contact the driving roller111. For example, the elastic member113may be a compressed coil spring having one end portion supported on the holder120and the other end portion supported on a rotation axis112-1of the driven roller112.

The separation member140may be switched from an exemplary normal position illustrated inFIG. 4to an exemplary separation position illustrated inFIG. 5. The separation position is a position of the driven roller112separated from the driving roller111by the separation member140that pulls the driven roller112in a direction opposite to the direction in which the elastic force of the elastic member113is applied. At the normal position, the separation member140does not interfere with the driven roller112. For example, the separation member140may be installed in the holder120to be able to pivot between the normal position and the separation position.

The handle member130may be connected to the separation member140to operate the separation member140. For example, the handle member130may be slidably installed in the holder120. The handle member130may be slidably supported on a rail121including a lower rail121-1and an upper rail121-2that may be separated from the lower rail121-1. The handle member130may slide to a first position and a second position respectively corresponding to the normal position and the separation position of the separation member140.

The separation member140may include a pivot shaft141supported on the holder120to function as a pivot center, a first connection portion142connected to the handle member130, and a hook portion143caught by the rotation shaft112-1of the driven roller112. When the separation member140pivots to the separation position, and a pivot trajectory of the hook portion143intrudes into the paper feed path8, that is, the pivot trajectory of the hook portion143goes beyond a contact portion114where the driven roller112and the driving roller111contact each other, the hook portion143may interfere with the jammed paper on the paper feed path8to prevent the separation member140from moving to the separation position. Furthermore, the jammed paper may be torn apart by the hook portion143so that removing the jammed paper may become more difficult. Thus, the position of the pivot shaft141may be determined such that the pivot trajectory of the hook portion143of the separation member140does not go beyond the contact portion114.

According to an exemplary embodiment, the pivot shaft141may be arranged at the side of the driven roller112with respect to the contact portion114to be spaced apart from the contact portion114farther than the rotation shaft112-1of the driven roller112. The pivot shaft141may be arranged around a line L connecting the centers of the driven roller112and the driving roller111. When the pivot shaft141is excessively separated from the line L, the pivot trajectory of the hook portion143increases so that the hook portion143may go over the contact portion114. For example, the pivot shaft141may be located on the line L.

A second connection portion131of the handle member130may be connected to the first connection portion142. For example, the first connection portion142may have a shape of a slot and the second connection portion131may have a shape of a protrusion inserted in the slot. The first and second connection portions142and131convert a sliding motion of the handle member130to a pivot motion of the separation member140. Although it is not illustrated, the first connection portion142may have a shape of a protrusion and the second connection portion131may have a shape of a slot. The length of the slot may be determined such that the pivot motion of the separation member140is available.

FIG. 6is a detailed view of an exemplary hook portion143. Referring toFIG. 6, the hook portion143may include a pull portion143-1that contacts the rotation shaft112-1of the driven roller112and pulls the rotation shaft112-1in the direction opposite to the direction in which the elastic force of the elastic member113is applied, as the separation member140pivots to the separation position, and an accommodation portion143-2on which the rotation shaft112-1of the driven roller112is accommodated when the separation member140is located at the separation position. The pull portion143-1may have a shape of a flat surface or a curved surface so that a pivot radius from the pivot shaft141gradually decreases. In other words, a pivot radius R1of the pull portion143-1gradually decreases from a first end portion143-1ato a second end portion143-1b. Thus, as the separation member140pivots from the normal position to the separation position, the pull portion143-1pulls the rotation shaft112-1of the driven roller112toward the pivot shaft141. Accordingly, the driven roller112may be separated from the driving roller111.

Since the driven roller112and the separation member140are disposed inside the image forming apparatus main body1, it may be difficult for a user to visually check whether the separation member140arrives at the separation position. The roller separation device according to an exemplary embodiment has a structure which enables a user to manually recognize whether the separation member140arrives at the separation position. In an example, a boundary portion143-3may be provided between the accommodation portion143-2and the pull portion143-1. A pivot radius R3of the boundary portion143-3from the pivot shaft141may be greater than a pivot radius R2of a second end portion143-1bof the pull portion143-1. Accordingly, when the separation member140pivots to the separation position, the contact between the rotation shaft112-1of the driven roller112and the pull portion143-1ends, and as the boundary portion143-3contacts the rotation shaft112-1, the driven roller112may be slightly moved close to the driving roller111by the elastic force of the elastic member113. In doing so, an impact (a sense of click) is transferred to the user via the separation member140and the handle member130. As a result, the user may manually recognize whether the separation member140arrives at the separation position.

A process of removing a jammed paper is described.

When a paper jam occurs, an operation of the image forming apparatus may be stopped. The image forming apparatus may output a paper jam message through a user interlace that is not illustrated. For example, the paper jam message may be output through a display (not shown) or output as an audible signal through a sound output device such as a buzzer or as a visible signal through a light emitting device such as a light emitting diode (LED).

The handle member130and the separation member140maybe respectively located at the first position and the normal position, as illustrated inFIG. 4. The driven roller112and the driving roller111maybe pressed to each other. In this state, as illustrated inFIG. 5, a user pulls a grip portion133of the handle member130exposed to the outside of the image forming apparatus main body1in a direction indicated by an arrow C1. The first and second connection portions142and131convert the sliding motion of the handle member130to the rotation motion of the separation member140, and thus the separation member140pivots in a direction indicated by an arrow D1inFIG. 5. As the separation member140pivots in the direction D1, the pull portion143-1contacts the rotation shaft112-1of the driven roller112.

FIG. 7is a cross-sectional view of an exemplary pull portion143-1contacting the rotational shaft112-1of the driven roller112. Referring toFIG. 7, when the pull portion143-1contacts the rotation shaft112-1of the driven roller112, an entrance angle θ of the pull portion143-1with respect to the rotation shaft112-1may be equal to or less than about 45°. The entrance angle θ may be defined as an angle between a line L1that is perpendicular to the line L and passing through the center112-1aof the rotation shaft112-1, and the pull portion143-1. In another expression, the entrance angle θ may be defined as an angle between a line L2that connects a contact point112-1bbetween the rotation shaft112-1and the pull portion143-1and the center112-1aof the rotation shaft112-1, and the line L. Accordingly, since a component force in a direction along the line L of a rotation force of the separation member140applied to the rotation shaft112-1, that is, a component force in a direction opposite to the direction in which the elastic force of the elastic member113is applied, may be increased, the driven roller112may be easily separated from the driving roller111with a relatively small force to operate the handle member130.

In the state illustrated inFIG. 7, when the separation member140pivots in the direction D1ofFIG. 5by pulling the handle member130, the contact between the rotation shaft112-1and the pull portion143-1ends and then the rotation shaft112-1contacts the boundary portion143-3. Since the pivot radius R3of the boundary portion143-3is greater than the pivot radius R2of the second end portion143-1bof the pull portion143-1, when a contact state with the pull portion143-1is converted to a contact state with the boundary portion143-3, the driven roller112may be slightly moved toward the driving roller111by the elastic force of the elastic member113. In doing so, an impact may be generated and transferred, for example, to the user's hand through the separation member140and the handle member130. The user may recognize that the separation member140arrives at the separation position, and, for example, then removes the force pulling the handle member130. The handle member130and the separation member140, as illustrated inFIG. 5, respectively arrive at the second position and the separation position, and the rotation shaft112-1of the driven roller112is accommodated on the accommodation portion143-2.

Since the elastic force of the elastic member113pushes the driven roller112toward the driving roller111, the elastic force acts as a rotation force to pivot the separation member140to the normal position. However, since the rotation shaft112may be accommodated on the accommodation portion143-2and the pivot radius R3of the boundary portion143-3may be greater than the pivot radius R1of the pull portion143-1, the rotation shaft112is difficult to escape from the accommodation portion143-2. In other words, the boundary portion143-3acts as a return prevention portion that prevents the separation member140from being returned from the separation position to the normal position. Accordingly, the separation member140may be maintained at the separation position and the driven roller112may be maintained in a state of being separated from the driving roller11.

As the pivot shaft141of the separation member140may be closer to an acting line of the elastic force of the elastic member113, the separation member140may be more stably maintained at the separation position. When the pivot shaft141of the separation member140may be located on the acting line of the elastic force of the elastic member113, the separation member140may be quite stably maintained at the separation position. When the acting line of the elastic force of the elastic member113and the pivot shaft141of the separation member140are located on the line L, the separation member140may be most stably maintained at the separation position.

When the handle member130is pushed in a direction indicted by an arrow C2in the state illustrated inFIG. 5after the jammed paper is removed, the sliding motion of the handle member130is converted to the pivot motion of the separation member140by the first and second connection portions142and131so that the separation member140pivots in a direction indicated by an arrow D2inFIG. 4. As the rotation shaft112-1escapes from the accommodation portion143-2, the driven roller112is moved by the elastic force of the elastic member113toward the driving roller111so as to contact the driving roller112. When the handle member130is completely pushed into the image forming apparatus main body1, the handle member130and the separation member140, respectively, arrive at the first position and the normal position illustrated inFIG. 4.

Since the feed roller110may be arranged adjacent to the paper feeding cassette2, a method may be considered in which the driven roller112may be separated from the driving roller111in engagement with an operation of pulling the paper feeding cassette2from the image forming apparatus main body1by connecting the paper feeding cassette2to the driven roller112, and the driven roller112may be contacted with the driving roller111by an operation of pushing the paper feeding cassette2into the image forming apparatus main body1. In this case, since the elastic force of the elastic member113is applied to the paper feeding cassette2, when the paper feeding cassette2is installed in the image forming apparatus main body1and the driven roller112contacts the driving roller111, the elastic force of the elastic member113acts in a direction of pushing the paper feeding cassette2out of the image forming apparatus main body1. An accommodation state of the paper feeding cassette2in the image forming apparatus main body1may become unstable, and the paper P picked up by the pickup roller21does not stably enter the paper feed path8, thereby generating a paper jam. The external appearance of the image forming apparatus may be degraded, for example, with in incomplete engagement of the image forming apparatus main body1and the paper feeding cassette2.

According to an exemplary embodiment, by using the sliding motion of the handle member130with respect to the image forming apparatus main body1, the separation member140may be switched between the normal position and the separation position to separate the driven roller112from the driving roller111, without the elastic force of the elastic member113acting on the paper feeding cassette2. Thus, installation stability of the paper feeding cassette2in the image forming apparatus main body1may be secured, and the quality of the external appearance of the image forming apparatus may be improved.

The separation member140at the normal position does not contact the driven roller112. Accordingly, the pressing state of the driven roller112against the driving roller111may be stably maintained so that reliability in the paper transfer may be improved.

When the separation member140is excessively rotated in the direction D1over the separation position or in the direction D2over the normal position, a support portion (not shown) of the holder120supporting the driven roller112may be damaged. The first and second connection portions142and131may be damaged as an impact may be applied to the first and second connection portions142and131.

FIG. 8is a cross-sectional view of a roller separation device having a first stopper144according to an exemplary embodiment. Referring toFIG. 8, the roller separation device according to an exemplary embodiment may include the first stopper144that prevents the separation member140from excessively rotating over the separation position. For example, the first stopper144may be provided on the separation member140. When the separation member140is located at the separation position, the first stopper144contacts the holder120. Accordingly, the separation member140may be maintained at the separation position without further pivoting in the direction D1. An excessive rotation prevention portion122that contacts the first stopper144when the separation member140may be located at the separation position may be provided on the holder120. In an example, the excessive rotation prevention portion122may be provided at an end portion of the upper rail121-2forming the rail121. The scope of the present inventive concept is not limited by the number of the first stoppers144. For example, only one first stopper144may be used or three or more first stoppers144may be used.

FIG. 9is a cross-sectional view of a roller separation device having a second stopper132according to an exemplary embodiment. Referring toFIG. 9, the roller separation device according to an exemplary embodiment may include a second stopper132that stops the sliding of the handle member130when the separation member140is located at the normal position. For example, the second stopper132may be provided on the handle member130. When the separation member140is located at the normal position, the second stopper132contacts the holder120. Accordingly, the handle member130does not slide over the first position, and the separation member140no longer pivots in the direction D2and is maintained at the normal position. A movement prevention portion123that contacts the second stopper132when the separation member140is located at the normal position may be provided on the holder120.

FIG. 10is a cross-sectional view of a roller separation device having a return spring150according to an exemplary embodiment. Referring toFIG. 10, the return spring150provides an elastic force to the separation member140in a direction to return to the normal position. For example, the return spring150may be a tension coil spring having one end portion and the other end portion respectively supported on the separation member140and the holder120. Although it is not illustrated, the return spring150may have a variety of shapes such as a compression coil spring, a torsion spring, a leaf spring, etc.

As the roller separation device according to an exemplary embodiment includes the return spring150, the separation member140may be maintained in the normal position by being separated from the driven roller112. Accordingly, interference in the rotation of the driven roller112or generation of noise as the separation member140located at the normal position moves and contacts the driven roller112may be prevented. Since the pressing state of the driven roller112and the driving roller111may be stably maintained, stability of the paper transfer may be improved. When the driven roller112is pressed again against the driving roller111after a jammed paper is removed, sliding of the handle member130is facilitated and thus the handle member130may slide with a relatively small force to return the separation member140to the normal position.

FIGS. 11 and 12are side views of a roller separation device according to an exemplary embodiment. Referring toFIGS. 11 and 12, when the paper feeding cassette2is inserted in the image forming apparatus main body1, the handle member130is pushed by the paper feeding cassette2to slide from the second position illustrated inFIG. 5to the first position illustrated inFIG. 4. To this end, a pressing portion2-1that pushes the handle member130to slide when the paper feeding cassette2is pushed into the image forming apparatus main body1is provided on the paper feeding cassette2.

As illustrated inFIG. 11, when the paper feeding cassette2is inserted in the image forming apparatus main body1, the pressing portion2-1blocks the grip portion133of the handle member130. Accordingly, when the paper feeding cassette2is inserted in the image forming apparatus main body1, the handle member130is not able to slide from the first position to the second position.

When a paper jam occurs, the paper feeding cassette2is pulled from the image forming apparatus main body1in the direction A2as illustrated inFIG. 12, the grip portion133of the handle member130is exposed to the outside. As the handle member130is pulled in the direction C1inFIG. 5by holding the grip portion133to slide to the second position, the separation member140may pivot to the separation position.

When the jammed paper is removed by pulling the handle member130from the image forming apparatus main body1as illustrated inFIG. 5and then printing is performed in a state in which the handle member130is not returned to the state illustrated inFIG. 4, since the driven roller112and the driving roller111are separated from each other, the paper P is not transferred and a print error may be generated.

According to an exemplary embodiment, when the paper feeding cassette2is inserted into the image forming apparatus main body1, the pressing portion2-1pushes the handle member130to slide to the first position. The separation member140may be returned to the normal position by the operation of inserting the paper feeding cassette2. According to the above structure, without intentionally returning the handle member130to the first position, the handle member130is returned to the first position by the operation of inserting the paper feeding cassette2and thus user convenience may be improved. An error that a print job is performed in a state in which the driven roller112is separated from the driving roller111may be prevented.

Since the separation member140is separated from the driven roller112in a state in which the driven roller112is pressed against the driving roller111, the elastic force of the elastic member113does not act on the separation member140. Accordingly, even when the pressing portion2-1of the paper feeding cassette2pushes the handle member130, the elastic force of the elastic member113does not affect the paper feeding cassette2and accommodation stability of the paper feeding cassette2in the image forming apparatus main body1may be maintained.

As illustrated inFIG. 10, when the return spring150is used, the paper feeding cassette2may be inserted into the image forming apparatus main body1with a relatively small force while returning the handle member130to the first position.

The handle member130may be moved to the first and second positions in engagement with the inserting/pulling operations of the paper feeding cassette2with respect to the image forming apparatus main body1. By the operation of pulling the paper feeding cassette2from the image forming apparatus main body1, the handle member130may be moved from the first position to the second position and thus the driven roller112may be separated from the driving roller111. By the operation of inserting the paper feeding cassette2back into the image forming apparatus main body1, the handle member130may be returned to the first position and thus the driven roller112may contact the driving roller111.

FIG. 13is a schematic cross-sectional view of a roller separation device according to an exemplary embodiment, illustrating a state in which the handle member130is located at the first position.FIG. 14is a schematic cross-sectional view of the roller separation device ofFIG. 13, illustrating a state in which the handle member130is located at the second position.FIG. 15is a schematic cross-sectional view of the roller separation device ofFIG. 13, illustrating a state in which a removal lever210is located at a removal position.FIG. 16is a schematic cross-sectional view of the roller separation device ofFIG. 13, illustrating a state in which the paper feeding cassette2is pulled from the image forming apparatus main body1.

Referring toFIG. 13, a removal lever210may be provided on the paper feeding cassette2. A first catch portion134may be provided on the handle member130. A second catch portion211may be provided on the removal lever210. When the handle member130is located at the first position, the second catch portion211is caught by the first catch portion134.

Referring toFIG. 14, when the handle member130is located at the second position, the second catch portion211is released from the first catch portion134. Accordingly, even when the handle member130is located at the second position, the paper feeding cassette2may be pulled from the image forming apparatus main body1to a position where loading of the paper P is possible.

The removal lever210may be switched from a catch position, to move the handle member130from the first position to the second position, where the second catch portion211is caught by the first catch portion134to the removal position where the second catch portion211is released from the first catch portion134. In an example, the removal lever210is installed on the paper feeding cassette2to be capable of pivoting around a pivot shaft220. A catch spring230is applied an elastic force in a direction in which the removal lever210is switched to the catch position. A variety of elastic members, for example, a compression coil spring, a torsion coil spring, etc., may be used as the catch spring230.

As illustrated inFIG. 13, when the paper feeding cassette2is pulled in the direction A2in a state in which the removal lever210is located at the catch position, the handle member130is moved from the first position to the second position and the separation member140pivots to the separation position. As illustrated inFIG. 14, when the handle member130arrives at the second position, the first stopper144is restricted by the excessive rotation prevention portion122and the handle member130is stopped. In this state, the separation member140is located at the separation position and the driven roller112is separated from the driving roller111. The amount of an elastic force of the catch spring230is determined considering the elastic force of the elastic member113that presses the driven roller112toward the driving roller111such that a catch state of the first and second catch portions134and211is maintained until the handle member130arrives at the second position.

When the paper feeding cassette2is pulled in the direction A2, the removal lever210pivots in a direction opposite to the direction in which the elastic force of the catch spring230is applied. The removal lever210pivots to the removal position where the second catch portion211is removed from the first catch portion134, as illustrated inFIG. 15, the paper feeding cassette2is in a state of being further pulled in the direction A2for paper loading, for example. When the paper feeding cassette2is further pulled in the direction A2, as illustrated inFIG. 16, the removal lever210is returned to the catch position by the elastic force of the catch spring230. A blocking portion240to block the removal member210from further pivoting beyond the catch position may be provided on the paper feeding cassette2. Accordingly, the paper feeding cassette2may be pulled from the image forming apparatus main body1, as illustrated inFIG. 16without interference between the removal member210and the handle member130.

In the state illustrated inFIG. 16, when the paper feeding cassette2is pushed in a direction indicated by an arrow A1(insertion direction), an interference portion212having a shape of an inclined surface and provided at a leading end portion of the removal lever210interferes with the first catch portion134and, as illustrated inFIG. 15, the removal lever210pivots in a direction so that the removal lever210is switched to the removal position. When the paper feeding cassette2is further pushed in the direction A1, the interference between the interference portion212and the first catch portion134ends and then the removal lever210is returned to the catch position as illustrated inFIG. 14. In this state, the pressing portion2-1of the paper feeding cassette2contacts the handle member130, for example, the grip portion133, and the handle member130pushed by the paper feeding cassette2is moved to the first position. When the second stopper132contacts the movement prevention portion123, the handle member130is located at the first position and the separation member140is located at a normal position. The driven roller112may be pressed against the driving roller111by the elastic force of the elastic member113.

Since the driven roller112and the driving roller111may contact/be separated from each other in engagement with the pulling/inserting operations of the paper feeding cassette2, user convenience may be improved. Since the elastic force of the elastic member113does not act on the paper feeding cassette2in a state in which the paper feeding cassette2is completely inserted in the image forming apparatus main body1, the insertion position of the paper feeding cassette2is not affected by the elastic force of the elastic member113.

Although in the above-described exemplary embodiments the handle member130that slides to switch the separation member140between the normal position and the separation position is used, the scope of the present inventive concept is not limited thereto.FIG. 17is a schematic cross-sectional view of a roller separation device according to an exemplary embodiment, illustrating a state in which a handle member130ais located at the first position.FIG. 18is a schematic cross-sectional view of the roller separation device ofFIG. 17, illustrating a state in which the handle member130ais located at the second position.

Referring toFIG. 17, the handle member130amay be provided on the image forming apparatus main body1to be capable of pivoting around a pivot shaft135. The handle member130amay include the second connection portion131connected to the first connection portion142of the separation member140and the grip portion133for pivoting the handle member130a. The pressing portion2-1that switches the handle member130ato the first position by pushing the grip portion133of the handle member130awhen the paper feeding cassette2is installed on the image forming apparatus main body1is provided on the paper feeding cassette2. In a state in which the paper feeding cassette2is inserted in the image forming apparatus main body1, the pressing portion2-1covers the grip portion133so that the grip portion133is not exposed to the outside.

As illustrated inFIG. 18, when the paper feeding cassette2is pulled from the image forming apparatus main body1in the direction A2, the grip portion133may be exposed to the outside. When the grip portion133is pulled, the handle member130arotates to be switched to the second position and accordingly the separation member140pivots to the separation position. The driven roller112may be separated from the driving roller111by the separation member140.

When the paper feeding cassette2is pushed in the direction A1, the pressing portion2-1pushes the grip portion133so that the handle member130ais returned to the first position. The separation member140is returned to the normal position and the driven roller112and the driving roller111are contacted with each other by the elastic force of the elastic member113.

The handle member130or130amay be formed integrally with the separation lever140.FIG. 19is a schematic cross-sectional view of a roller separation device according to an exemplary embodiment, illustrating a state in which a separation member140ais located at a normal position.FIG. 20is a schematic cross-sectional view of the roller separation device ofFIG. 19, illustrating a state in which the separation member140ais located at a separation position.

Referring toFIGS. 19 and 20, the separation member140amay be substantially the same as the separation member140ofFIGS. 4 to 10, except that a grip portion145is provided to switch the separation member140afrom the normal position to the separation position and the first connection portion142is not provided. The grip portion145may be located at the opposite side of the hook portion143with respect to the pivot shaft141.

The pressing portion2-1that switches the separation member140afrom the separation position to the normal position by pushing the grip portion145of the separation member140awhen the paper feeding cassette2is inserted in the image forming apparatus main body1, is provided on the paper feeding cassette2. When the paper feeding cassette2is inserted in the image forming apparatus main body1, the grip portion145is covered by the paper feeding cassette2so as not to be exposed to the outside.

As illustrated inFIG. 20, when the paper feeding cassette2is pulled from the image forming apparatus main body1in the direction A2, the grip portion145is exposed to the outside. When the grip portion145is pulled, the separation member140arotates to be switched from the normal position to the separation position. Accordingly, the driven roller112is separated from the driving roller111.

When the paper feeding cassette2is pushed in the direction A1, the pressing portion2-1pushes the grip portion145so that the separation member140ais returned to the normal position. Then, the driven roller112and the driving roller111are contacted with each other by the elastic force of the elastic member113.

Although in the above-described exemplary embodiment the image forming apparatus employing the print unit3of an electrophotographic type is described, the scope of the present inventive concept is not limited thereto. The roller separation device of the above-described exemplary embodiment may be applied to an image forming apparatus employing various printing methods such as an inkjet method, a thermal transfer method, etc.

While one or more embodiments of the present inventive concept have been described with reference to the figures, 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 present inventive concept as defined by the following claims.