Print medium supplying device and image forming apparatus having the same

A print medium supplying device, includes a frame, a mounting plate to mount a print medium, an elevating unit to move upward and downward the mounting plate within the frame, and an elastic unit which comprises an installation unit disposed to one of the frame and the mounting plate, a coupling unit coupled to an other of the frame and the mounting plate, and a spring unit provided between the installation unit and the coupling unit to elastically weaken a falling motion of the mounting plate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(a) from Korean Patent Application No. 10-2007-0047742, filed on May 16, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present general inventive concept relates to a print medium supplying device and an image forming apparatus having the same, and more particularly, to a print medium supplying device and an image forming apparatus to reduce a falling impact of a mounting plate on which a print medium is mounted when the print medium supplying device is in a mounting position and is separated from the image forming apparatus.

2. Description of the Related Art

In general, a print medium supplying device is employed in an image forming apparatus such as a printer, a copy machine, a facsimile, etc., and picks up a print medium mounted inside thereof, one by one, to be supplied to the image forming apparatus. The print medium supplying device may be classified according to a print medium mounting capacity such as a print medium supplying device having the print medium mounting capacity within several hundred sheets of print media, and a print medium supplying device of high capacity having the print medium mounting capacity of approximate 2,000 sheets of print media.

Referring toFIG. 1, a related art print medium supplying device includes a frame11accommodating a print medium1therein, and a mounting plate13disposed within the frame11to move upward and downward. The print medium1is mounted on the mounting plate13. The mounting plate13is driven by a driving force supplied from a driving source (not illustrated) provided in an image forming apparatus, and an elevating unit15. The elevating unit15includes first and second pulleys16and17distantly disposed in a vertical direction of the frame11, and a timing belt19to wind around the first and second pulleys16and17. The first pulley16receives the driving force supplied from the driving source through a shaft16a and a coupler (not illustrated) provided on a same axis to rotate the timing belt19. The mounting plate13is disposed proximate to the timing belt19to move upward and downward depending on a driving direction of the timing belt19. Accordingly, the print medium1can be smoothly supplied by adjusting a height of the mounting plate13according to a number of the print media1mounted on the mounting plate13.

If the print medium supplying device is detached from the image forming apparatus to additionally mount the print medium1, the coupler is separated so that the driving force transmitted from the driving source to the shaft16a can be intercepted. Accordingly, the first and second pulleys16and17rotate free, and the mounting plate13falls free by its own weight. Accordingly, the print medium supplying device may be damaged, and noises may be generated.

The related art print medium supplying device further includes a gear21provided coaxially with the first pulley16, and a gear oil damper23engaged to the gear21to prevent the mounting plate13from falling free. Accordingly, when the coupler is separated, the mounting plate13falls down while the first pulley16rotates in a low speed, thereby relieving the problem related to the free falling of the mounting plate13.

However, in the related art print medium supplying device as illustrated inFIG. 1, since the weight on the mounting plate13and a height of a central point of the weight thereon vary according to a number of the print media1mounted on the mounting plate13, it is difficult to design the gear oil damper23to be appropriate for such various conditions.

Accordingly, the gear oil damper23is designed based on a condition that there is no print medium1mounted on the mounting plate13.

However, if the gear oil damper23is designed under this condition, a buffering action corresponding to the gear oil damper23is weakened. Accordingly, if the print medium supplying device is detached from the image forming apparatus while a considerable number of print media1are mounted on the mounting plate13, the print medium supplying device may be damaged, and noises may be generated.

SUMMARY OF THE INVENTION

The present general inventive concept to provide a print medium supplying device and an image forming apparatus having the same to reduce a falling speed of a mounting plate irrespective of a number of mounted print media to prevent the print medium supplying device from being damaged and to reduce noises when the print medium supplying device is in a mounting position and is separated from the image forming apparatus.

The foregoing and/or other aspects and utilities of the present general inventive concept can be achieved by providing a print medium supplying device, including a frame, a mounting plate to mount a print medium, an elevating unit to move upward and downward the mounting plate within the frame, and an elastic unit which includes an installation unit disposed to one of the frame and the mounting plate, a coupling unit coupled to an other of the frame and the mounting plate, and a spring unit disposed between the installation unit and the coupling unit to elastically weaken a falling motion of the mounting plate.

The elastic unit may further include an elastic plate having a tape shape, and spirally winds around the installation unit.

The coupling unit may be disposed in an end portion of the spring unit to be engaged to the mounting plate, if the mounting plate falls below a predetermined height.

The elastic unit may be provided in plurality, and each elastic unit may be provided at a plurality of positions along a perimeter of the mounting plate.

The elevating unit may includes a driving pulley disposed in the frame to be rotated by an applied driving force, a driven pulley disposed in the frame to be distanced from the driving pulley in a vertical direction of the frame, and a belt to rotatably wind around the driving pulley and the driven pulley, and is coupled with the mounting plate.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing a print medium supplying device, including a frame, a mounting plate disposed in the frame to move upward and downward, and to mount a print medium, an elevating unit disposed in the frame to adjust a height of the mounting plate based on a number of the print media mounted on the mounting plate, and an elastic unit to elastically support the mounting plate to reduce a falling impact when the mounting plate lifted to a predetermined height falls down according to a release of a driving force to drive the elevating unit.

The elastic unit may include an installation unit disposed in the frame, a coupling unit to selectively couple the mounting plate, and a spring unit provided between the installation unit and the coupling unit to elastically weaken a falling motion of the mounting plate.

The elastic unit may include an elastic plate having a tape shape, and spirally winds around the installation unit.

The positions of the frame may respectively correspond to a minimum height and a maximum height of the mounting plate disposed to move upward and downward with respect to the frame may be respectively referred to a first position and a second position, the installation unit may be disposed between the first position and the second position, may elastically support the mounting plate when the mounting plate is positioned between the first position and the installation unit, and may be separated from the mounting plate when the mounting plate is positioned between the installation unit and the second position.

The elastic unit may be provided in plurality, and each elastic unit may be provided at a plurality of positions along a perimeter of the mounting plate.

The elevating unit may include a driving pulley disposed in the frame to be rotated by an applied driving force, a driven pulley disposed in the frame to be distanced from the driving pulley in a vertical direction of the frame, and a belt to rotatably wind around the driving pulley and the driven pulley, and may be coupled with the mounting plate.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing an image forming apparatus, including a print medium supplying device comprising a frame, a mounting plate to mount a print medium, an elevating unit to move upward and downward the mounting plate within the frame, and an elastic unit which comprises an installation unit disposed to one of the frame and the mounting plate, a coupling unit coupled to an other of the frame and the mounting plate, and a spring unit provided between the installation unit and the coupling unit to elastically weaken a falling motion of the mounting plate, and an image forming unit to form an image with respect to the print medium supplied by the print medium supplying device.

The elastic unit may further include an elastic plate having a tape shape, and spirally winds around the installation unit.

The coupling unit may be disposed in an end portion of the spring unit to be engaged to the mounting plate, if the mounting plate falls below a predetermined height.

The elastic unit may be provided in plurality, and each elastic unit may be provided at a plurality of positions along a perimeter of the mounting plate.

The elevating unit may include a driving pulley disposed in the frame to be rotated by an applied driving force, a driven pulley disposed in the frame to be distanced from the driving pulley in a vertical direction of the frame, and a belt to rotatably wind around the driving pulley and the driven pulley, and is coupled with the mounting plate.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing an image forming apparatus, including a print medium supplying device comprising a frame, a mounting plate disposed in the frame to move upward and downward, and to mount a print medium, an elevating unit which is disposed in the frame to adjust a height of the mounting plate based on a number of the print media mounted on the mounting plate, and an elastic unit to elastically support the mounting plate to reduce a falling impact when the mounting plate which is lifted to a predetermined height falls down according to a release of a driving force to drive the elevating unit, and an image forming unit to form an image with respect to the print medium supplied by the print medium supplying device.

The elastic unit may include an installation unit disposed in the frame, a coupling unit to selectively couple the mounting plate, and a spring unit provided between the installation unit and the coupling unit to elastically weaken a falling motion of the mounting plate.

The elastic unit may include an elastic plate having a tape shape, and spirally winds around the installation unit.

The positions of the frame may respectively correspond to a minimum height and a maximum height of the mounting plate disposed to move upward and downward with respect to the frame may be respectively referred to a first position and a second position, the installation unit may be disposed between the first position and the second position, may elastically support the mounting plate when the mounting plate is positioned between the first position and the installation unit, and may be separated from the mounting plate when the mounting plate is positioned between the installation unit and the second position.

The elastic unit may be provided in plurality, and each elastic unit is provided at a plurality of positions along a perimeter of the mounting plate.

The elevating unit may include a driving pulley disposed in the frame to be rotated by an applied driving force, a driven pulley disposed in the frame to be distanced from the driving pulley in a vertical direction of the frame, and a belt to rotatably wind around the driving pulley and the driven pulley, and is coupled with the mounting plate.

The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a print medium supplying device usable with an image forming apparatus, the print medium supplying device comprising a frame, a mounting plate disposed proximate to the frame to store and to supply a print medium, and one or more elastic units disposed between the frame and the mounting plate to elastically weaken a falling motion of the mounting plate.

The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing an image forming apparatus, comprising a print medium supplying device comprising a frame, a mounting plate disposed proximate to the frame to store and to distribute a print medium, and an elastic unit disposed between the frame and the mounting plate to elastically weaken a falling motion of the mounting plate, and an image forming unit to form an image on the print medium supplied by the print medium supplying device.

The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a print medium supplying device usable with an image forming apparatus, the print medium supplying device comprising a frame, a mounting plate disposed in the frame to move with respect to the frame to support a print medium, and an elastic unit disposed at a position within a moving distance of the mounting plate not to apply an elastic force to the moving plate and to apply a variable elastic force to the moving plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated inFIGS. 2 to 6, a print medium supplying device usable with an image forming apparatus according to an exemplary embodiment of the present general inventive concept includes a frame51, a mounting plate55to mount a print medium, an elevating unit60to move upward and downward the mounting plate55inside the frame51and an elastic unit70.

The frame51is detachably mounted to an image forming apparatus, and accommodates a print medium50therein. The mounting plate55is disposed in the frame51, and moves upward and downward by the elevating unit60. The elevating unit60includes a sub frame61disposed in the frame51, a driving pulley63and a driven pulley65distantly disposed to the sub frame61, and a belt67to wind around the driving pulley63and the driven pulley65. The driving pulley63receives a driving force supplied from a driving source85through a shaft81and a coupler83provided on a same axis to enable the belt67to rotate. The driven pulley65is disposed to the frame51to be distanced from the driving pulley63in a vertical direction of the frame51. The belt67is provided, for example, as a timing belt, and winds around the driving pulley63and the driven pulley65. The mount plate55is coupled to the belt67to move upward and downward depending on a rotation of the belt67. Accordingly, the print medium50can be smoothly supplied by adjusting a height of the mounting plate55according to a number of the print media50mounted on the mounting plate55. The image forming apparatus may include a pick-up unit30as a print medium feeding unit disposed to pick-up and feed the print medium50toward an image forming unit (not illustrated) along a feeding and printing path. The pick-up unit30may be disposed on a position to pick-up and feed the print medium50.

Referring toFIGS. 4A and 4B, when the print medium supplying device, according to the exemplary embodiment of the present general inventive concept, is separated from the image forming apparatus in the mounting position, the elastic unit70reduces a falling speed of the mounting plate55irrespective of an amount of the mounted print medium50. For this, the elastic unit70is provided in plurality, and may be provided at a plurality of positions along a perimeter of the mount plate55.

The respective elastic units70include an installation unit71to couple one of the frame51and the mounting plate55, and a spring unit75to elastically reduce the falling speed of a coupling unit73and the mounting plate55.

The installation unit71is employed to securely couple an end portion of the spring unit75, and may couple the frame51as illustrated inFIG. 3. Alternatively, the installation unit71may couple the mounting plate55. As illustrated therein, the installation unit71may be provided separately from the spring unit75. Alternatively, the installation unit71may be integrally provided in an end portion of the spring unit75. The installation unit71may be stationary with respect to the frame51, and the coupling unit73may be movable with respect to the installation unit71to move together with the mounting plate55to apply an elastic force to the mounting plate55. The elastic force may be variable according to a height of the mounting plate55within the frame51.

The coupling unit73is disposed at an end portion of the spring unit75, and is coupled to the other of the frame51and the mounting plate55. For example, as illustrated inFIG. 3, if the installation unit71is coupled to the frame51, the coupling unit73is coupled to the mounting plate55. Here, since the coupling unit73is capable of being selectively coupled with the mounting plate55, the coupling unit73is engaged with the mounting plate55when the mounting plate55falls below a predetermined height, and is distanced from the mounting plate55when the mounting plate55is maintained to a position above a predetermined height.

That is, if the positions of the frame51corresponding to a minimum height and a maximum height of the mounting plate55disposed to move upward and downward with respect to the frame51are respectively referred to a first position and a second position, the installation unit71is disposed between the first position and the second position. Accordingly, when the mounting plate55is positioned between the first position and the installation unit71, the mounting plate55is elastically supported by the installation unit71, or the coupling unit73. Also, when the mounting plate55is positioned between the installation unit71and the second position, the installation unit71, or the coupling unit73is separated from the mounting plate55.

The spring unit75is provided between the installation unit71and the coupling unit73to elastically weaken the falling motion of the mounting plate55. For this, the spring unit75may include an elastic plate having a tape shape and spirally winding around the installation unit71.

Since the mounting plate55is movable with respect to the pick-up unit30such that the print medium50can be picked-up by the pick-up unit30, the elastic unit70may not apply the elastic force to the mounting plate55when a distance between the pick-up unit30and the mounting plate55is not greater than a reference distance representing a number of print media50mounted on the mounting plate55, and may apply a variable elastic force to the mounting plate55according to the distance to support the mounting plate55when the distance is greater than the reference distance.

Hereinafter, an operating state of the print medium supplying device according to the exemplary embodiment of the present general inventive concept will be described by referring toFIGS. 5 and 6.

For example, if the print medium supplying device according to the exemplary embodiment of the present general inventive concept accommodates a maximum 2,000 sheets of print media having a size of A4, a total mass of the print media is approximately 11 to 13 kg, and a mounted height thereof is approximately 220 mm. Here, since an uppermost positioned print medium among the accommodated entire print media50is positioned in a supplying position, the mounting plate55is positioned near a lower surface of the frame51. Here, the coupling unit73is engaged to the mounting plate55, and the spring unit75is expanded to have a maximum length thereof.

Here, if the elastic unit70is provided at four places along the perimeter of the mounting plate55, and a buffering force of1kg gravity is applied to each elastic unit70, a total force of 4 kg gravity can be reduced. Accordingly, a force of approximately 7 to 9 kg gravity can be applied to the mounting plate55. This state is maintained irrespectively of whether to supply the driving force to the print medium supplying device.

While the driving force is supplied to the print medium supplying device, if the number of the print media50mounted on the mounting plate55is reduced, the mounting plate55moves upward to a position as illustrated inFIG. 5so that the print medium mounted on an uppermost portion thereof can maintain the supplying position.

For example, if approximately 1,000 sheets of the print media50are mounted on the mounting plate55, the mounting plate55moves upward by approximately 100 mm or greater as compared to a mounting of approximately 2,000 sheets of the print media50. Here, the total mass of the print medium50is approximately 6 to 7 kg. If the elastic unit70is disposed in a position of approximate 100 mm from a bottom surface, the mounting plate55is distanced apart from the coupling unit73as illustrated inFIG. 6.

The print medium supplying device is separated from the image forming apparatus, for example, as described below.

If the number of the print media50mounted on the mounting plate55is less than 1,000 sheets, the force is applied to the elastic unit70during feeding of the print medium50. Thus, if the print medium supplying device is separated from the image forming apparatus, the driving force supplied from the driving source85to the shaft81and the driving pulley63is intercepted in the coupler83. Accordingly, the mounting plate55falls free to reach an installation position of the elastic unit70. The mounting plate55falling free is engaged to the coupling unit73in the installation position of the elastic unit70so that the elastic unit70can accomplish a buffering action. Here, the buffering force of the elastic unit70increases in proportion to a falling distance of the mounting plate55, thereby efficiently reducing a free falling impact of the mounting plate55.

If the number of the print media50mounted on the mounting plate55is greater than 1,000 sheets, the mounting plate55is maintained to be coupled to the coupling unit73of the elastic unit70during supplying the print medium50. Accordingly, although the mounting plate55is moved downward as the driving force supplied from the driving source85to the shaft81and the driving pulley63is intercepted in the coupler83as a result of that the print medium supplying device is separated from the image forming apparatus, the mounting plate55is buffered by the elastic unit70without falling free. Here, the buffering force of the elastic unit70increases in proportion to a falling distance of the mounting plate55, thereby efficiently reducing the free falling impact of the mounting plate55.

Referring toFIG. 7, an image forming apparatus according to an exemplary embodiment of the present general inventive concept includes a print medium supplying device110being capable of supplying a print medium in a big capacity, and an image forming unit100to form an image to the print medium supplied by the print medium supplying device110. The image forming apparatus may have a pick-up unit30to pick-up and feed the print medium50toward the image forming unit100. Here, the print medium supplying device110may have the same configuration as the print medium supplying device according to the exemplary embodiment of the present general inventive concept as illustrated inFIGS. 2 to 6.

As described above, the present general inventive concept provides a print medium supplying device and an image forming apparatus having the same being provided with an elastic unit instead of a conventional gear oil damper to reduce a falling speed of a mounting plate irrespective of a number of mounted print media, thereby preventing the print medium supplying device from being damaged, and reducing noises when the print medium supplying device in a mounting position is separated from the image forming apparatus.