This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 2005-80824, filed Aug. 31, 2005, in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to a printing media supply device for an image forming apparatus, which is capable of preventing multifeeding (that is, transferring several printing media into a main body of an image forming apparatus at one time) when the printing media in a printing media supply cassette is picked up.
2. Description of the Related Art
In general, an image forming apparatus includes a printing media supply device for supplying printing media, such as paper, fabric, film or the like, into a main body of the apparatus. Such a printing media supply device typically has a separate pick-up roller to pick up the printing media sheet by sheet.
One example of a printing media supply device of a conventional image forming apparatus is schematically shown in
As shown in
The pick-up roller 120 is installed in an upper portion of the printing media supply cassette 110 to contact the printing media P stacked in the printing media supply cassette 110. The pick-up roller 120 has a pick-up member 121 for picking up the printing media P and a rotation member 122 coupled with a rotation shaft 123 while supporting the pick-up member 121.
The pick-up member 121 is provided on the rotation member 122, which is brought into contact with the printing media P, and exerts pressure on the printing media P. The pick-up member 121 is formed of, for example, a rubber material with a high elasticity to increase the frictional force on the printing media P. Further, on an outer circumferential surface of the pick-up member 121, saw-teethed protrusions 121a (see
In this process of feeding printing media, however, the pressure exerted on the top-most printing medium by the pick-up roller varies depending on the amount of printing media stacked in the printing media supply cassette.
Accordingly, there is a need for an improved printing media supply device which is capable of preventing multifeeding regardless of the amount of printing media stacked in a printing media supply cassette.
An aspect of the present invention is to address at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a printing media supply device for use in an image forming apparatus, which is capable of preventing multifeeding (that is, feeding several printing media into a main body of an image forming apparatus at one time) regardless of the amount of printing media stacked in a printing media supply cassette when the printing media are picked up.
In accordance with an aspect of the present invention, a printing media supply device for use in an image forming apparatus includes a printing media supply cassette in which printing media is stacked, and a pick-up roller which picks up the stacked printing media. The pick-up roller comprises a pick-up member for picking up the printing media, and a rotation member for supporting the pick-up member which is connected to a rotation shaft. The rotation member has a buffer surface at a leading edge portion.
The printing media supply cassette may include a base plate on which the printing media is stacked, a first elastic member for pushing up one portion of the base plate, and a pair of fingers which are mounted at both ends of the base plate to be interlocked with the base plate so as to hinder movement of the printing media, so that the printing media is transferred sheet by sheet.
The pick-up member may be provided with a plurality of protrusions formed along an outer circumferential surface. The pick-up member may be formed of a rubber material. The pick-up member may be formed into a band shape. An inner circumferential surface of the pick-up member near a leading edge portion thereof may be formed into a wavy shape, or the pick-up member may be provided with a void formed at a leading edge portion therein. A predetermined space may be formed between the pick-up member and the rotation member, near the leading edge portion of the rotation member.
The rotation member may have a first rotation member and a second rotation member which is disposed to face the first rotation member, and which is provided with a support plate supporting the pick-up member.
The buffer surface of the rotation member may be formed so as to expose side surfaces of the pick-up member, and formed such that side surfaces of the pick-up member become more exposed as they approach the leading edge portion of the pick-up roller.
In accordance with another aspect of the present invention, a printing media supply device for use in an image forming apparatus includes a printing media supply cassette in which a number of printing media are stacked, and a pick-up roller which picks up the printing media stacked in the printing media supply cassette. The pick-up roller has a pick-up member for picking up the printing media, a movable member mounted to a rotation shaft to support the pick-up member, and a rotation member which is disposed on both side surfaces of the movable member to be mounted to the rotation shaft. A second elastic member is disposed at a rear portion of the rotation member to press the pick-up member.
The rotation member may have a first rotation member, and a second rotation member which is disposed to face the first rotation member, and which is provided with a support plate at a rear end portion. The support plate of the second rotation part may be provided with a protrusion part onto which the second elastic member is inserted.
The above and other objects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Throughout the drawings, the same reference numerals will be understood to refer to the same elements, features, and structures.
The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
A printing media supply device for use in an image forming apparatus in accordance with the present invention will now be described, with reference to the accompanying drawings.
Referring to the drawings, a printing media supply device 200 in accordance with a first exemplary embodiment of the present invention includes a printing media supply cassette 210 and a pick-up roller 220 with a buffer part for absorbing pressure from printing media, such as paper, fabric, film or the like, when picking up the printing media.
The printing media supply cassette 210 is detachably installed in a main body of the image forming apparatus. Components such as an image forming unit, a fusing unit, a printing media discharge unit are included in the main body of the image forming apparatus. Since the configuration of such components is well-known to those skilled in the art, a detailed description will be omitted for clarity and conciseness.
The printing media supply cassette 210 has a base plate 211, a first elastic member 212 and a finger 213. Printing media is stacked on the base plate 211, and the base plate 211 is installed a predetermined distance away from the pick-up roller 220. The first elastic member 212 pushes one side of the base plate 211 upward, so that the uppermost one of the printing media stacked on the base plate 211 is brought into a contact with the pick-up roller 220 when the pick-up roller 220 is rotated. The fingers 213 are linked with the base plate 211 so as to hinder forward movement of the printing media at the leading ends of the printing media, thereby separating the printing media and enabling the media to be supplied sheet by sheet.
The pick-up roller 220 picks up the printing media stacked in the printing media supply cassette 210, and then transfers the printing media into the main body of the image forming apparatus. To do so, the pick-up roller 220 has a pick-up member 221 and a rotation member 222, and is installed in an upper portion of the printing media supply cassette 210.
The pick-up member 221 transfers the printing media into the main body of the image forming apparatus by using frictional force generated when it is brought into contact with the printing media. A plurality of protrusions 221a may be formed along an outer circumferential surface of the pick-up member 221, as shown in
The rotation member 222 is disposed at both ends of the pick-up member 221 and the shape of the side of the rotation member corresponds to the shape of the pick-up member 221. The rotation member 222, together with the pick-up member 221, is coupled with a rotation shaft 223 through an opening 226 of the rotation member 222 to be rotatable relative to the main body of the image forming apparatus. The rotation member 222 can be formed integrally with the rotation shaft 223, or, for example, may be formed by assembling a pair of rotation members 222′, 222″. In the latter case, the rotation member 222 comprises a first rotation member 222′ and a second rotation member 222″, which are disposed to face each other. Any one of the rotation members 222′ and 222″ may be provided with the support plate 222c to support the pick-up member 221.
The radius of the rotation member 222 may be less than that of the pick-up member 221 so that it does not affect the contact of the pick-up member 221 with the printing media.
In the present exemplary embodiment, the rotation member 222 has a buffer surface 222a which is formed by cutting away a portion of a leading edge portion. The buffer surface 222a serves as a buffer part to absorb pressure from the printing media when the pick-up member 221 presses the printing media to pick up one sheet. The buffer surface 222a may be formed in the leading edge portion 222b of the rotation member 222, and exposes a side surface of the pick-up member 221 to the outside. The buffer surface 222a may be formed such that the side surfaces of the pick-up member 221 become more exposed when approaching the leading edge portion 221c of the pick-up roller 220. With the pick-up roller 220 configured like this, the pick-up member 221 absorbs the pressure from the printing media to a leading edge portion 221c of the pick-up member 221 when pressing the printing media.
As shown in
The shape of the pick-up member 221 is not limited to the just-described first exemplary embodiment, and can be formed of a variety of shapes.
Referring to
Referring to
Thus, the pick-up rollers of the first to third exemplary embodiment absorb different amounts of pressure from the printing media, even though they have buffer surfaces with the same shape. For example, if a printing media supply device equipped with the pick-up member in accordance with the first exemplary embodiment operates optimally when about 250 sheets of printing media are stacked therein, a printing media supply device equipped with the pick-up member in accordance with the second (or the third) exemplary embodiment may operate optimally when about 100 (or 500) sheets of printing media are stacked therein.
The operation of the printing media supply device for use in an image forming apparatus with the above-described configuration, in accordance with the first exemplary embodiment of the present invention, will now be described with reference to
As shown in
At this time, the pressure pushing the printing media P upward by the first elastic member 212 is greater when there is a large amount of printing media P stacked in the base plate 211 (see
While the pick-up roller 220 is rotating counterclockwise, the pick-up member 221 presses the printing media P with the approximately uniform pressure and transfers the uppermost printing media P by a uniform frictional force to supply the printing media P into the main body of the image forming apparatus.
In the printing media supply device equipped with the pick-up roller 220 in accordance with the present invention, the printing media supply efficiency is improved since the printing media P is transferred with uniform pressure, even when a large quantity of printing media P is stacked in the printing media supply cassette. The printing media supply device equipped with the pick-up roller 320 (or 420) in accordance with the second (or third) exemplary embodiment operates substantially the same way as the printing media supply device equipped with the pick-up roller 220 in accordance with the first exemplary embodiment. Fourth Exemplary Embodiment
A pick-up roller in accordance with a fourth exemplary embodiment of the present invention has the capability to absorb pressure by a different mechanism that of the first to third exemplary embodiments.
Referring to the drawings, a printing media supply device 500 for use in an image forming device in accordance with the fourth exemplary embodiment of the present invention includes a printing media supply cassette 510 and a pick-up roller 520 with a buffer part for absorbing pressure from a printing media when picking up the printing media.
In the printing media supply device for use in an image forming apparatus in accordance with the fourth exemplary embodiment, the printing media supply cassette 510 is substantially identical to the printing media supply device of the first, second or third exemplary embodiments, so a detailed description will not be repeated. In the fourth exemplary embodiment, the pick-up roller pick-up roller 520 for absorbing pressure from the printing media when the printing media is picked up is configured as follows.
As shown in
The pick-up member 521 for picking up the printing media has a substantially identical structure to that of the first exemplary embodiment. The pick-up member 521 can be mounted around an outer circumferential surface 525a of the movable member 525.
The movable member 525 supports the pick-up member 521 and is mounted around the rotation shaft 523. The movable member 525 may be mounted so that it is movable relative to the rotation shaft 523. Therefore, when the pick-up roller 520 is brought into contact with the printing media, the movable member 525 can be rotated in a direction opposite to that of the rotation member 522, so that pressure from the printing media can be absorbed by the movable member 525. Accordingly, the pick-up roller in accordance with the fourth exemplary embodiment can absorb pressure, like the pick-up rollers of the first, second or third exemplary embodiments which have a buffer surface in the leading edge portion of the rotation member.
The rotation member 522 is disposed at both sides of the movable member 525 and is mounted around the rotation shaft 523. The rotation member 522 may comprise a first rotation member 522b and a second rotation member 522a. The second rotation member 522a may face the first rotation member 522b. The second rotation member 522a is provided with a support plate 522c at its rear end portion so that a second elastic member 524 can be mounted on the support plate 522c. The support plate 522c may be provided with a protrusion part 522d, and the second elastic member 524 may be disposed about the protrusion part 522d. In the rear end portion of the rotation member 522, a cutaway portion 522e can be formed to facilitate rotation of the rotation member 522. The rotation shaft 523 is connected in the center portion of the rotation member 522. As shown in
If the movable member 525 is rotated backward about the rotation shaft 523 when the pick-up roller 520 is brought into contact with the printing media, the second elastic member 524 exerts an elastic force on the pick-up member 521 so as to return the movable member 525 back to its original position.
The operation of the fourth exemplary embodiment of the printing media supply device will now be described with reference to
As shown in
Similarly, in
While the pick-up roller 520 is rotating counterclockwise, the pick-up member 521 presses the printing media P with approximately uniform pressure and transfers the printing media P by a uniform frictional force to supply it into the main body of the image forming apparatus.
Accordingly, the pick-up roller 520 in accordance with the fourth exemplary embodiment has substantially the same capability to absorb pressure as the pick-up roller 220 (or 320 or 420) in accordance with the first (or second or third) exemplary embodiment. Further, since the printing media P are transferred by applying a uniform pressure even when there is a large amount of printing media P stacked on the printing media supply cassette, the printing media supply efficiency is improved.
As described above, the printing media supply device of the image forming apparatus in accordance with the present invention can maintain the pressure exerted on the printing media by the pick-up roller approximately uniform regardless of the amount of printing media to be picked up and supplied into the main body of the image forming apparatus. Therefore, even when there is a large amount of printing media stacked in the printing media supply device, the pickup roller can supply the printing media sheet by sheet, without multifeeding or crumpling.
Accordingly, since the printing media are supplied into the main body of the image forming apparatus by the pick-up roller without multifeeding and without being crumpled, the printing media supply efficiency can be improved. Further, the quality of images developed on the printing media is improved because of the improved printing media supply efficiency.
While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled 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.
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