A sheet feeding apparatus

Abstract: A sheet feeding device of a printing device comprising: a pickup roller (510); a knockup plate (220) for loading a paper; a feed roller for feeding a paper picked up and transmitted by said pickup roller and transmitting to a push part; a knockup plate controller (530) adhering said pickup roller closely to said knockup plate only if it picks up papers; and a document guider (300,320) guiding a document in order to be engaged into said feed roller if said document is inserted in the state that said knockup plate is diverged with said pickup roller.

Description: The present invention relates to a sheet feeding apparatus of a printing device. More particularly, the invention relates to a sheet feeding device which combines manual and automatic feeding in which manual pickup and auto pickup of the sheet can be achieved at the same time, via substantially the same transport path, without changing the position of the manual device. Prior art sheet feeding devices in printing devices have generally, been one of two kinds. One is a device which comprises an auto feeding device loading a plurality of papers and a separate special manual device generally provided at some other part of the printing device. This type of device differentiates the transport path for manual feeding from the transport path for auto sheet feeding. The other prior art device performs manual feeding by removing auto feeding papers loaded in a knockup plate and operating an aided guide device and so on. Therefore, for a user who has been used to using an auto sheet feeding device, to perform feeding in manual method in some cases, for example when using a form or other such document, etc, it is very inconvenient to insert a paper into a manual feeding device which has a different opening, or to use an aided guide device. US-A-5 145 160 describes an apparatus for automatic paper feeding and manual paper feeding. The manual paper feeding tray is in two halves, geared together. Movement of the upper half from a stored position to a use position also causes the end of the lower half to move the paper in the automatic feed tray away from the pickup roller. US-A-5 370 380 describes a paper feeding apparatus including a manual lever-operated cam which acts to depress the knockup plate of an automatic paper feed tray, to move the papers away from a pickup roller, thereby to allow manual feeding. US-A-5 346 197 describes a paper feeding cartridge for manual and automatic feeding. The lid of the cartridge is pivotally attached to the body of the cartridge. A manually operated lever at the rear of the cartridge acts to raise the rear and depress the front of the lid. The leading edge of the lid depresses the stack of paper for automatic feeding, so that it is moved away from a pickup roller. One purpose of the present invention is to provide a device for increasing convenience by embodying manual feeding and auto feeding in a manual feeding state without any special operation, and decreasing costs by removing parts and functionality for recognising manual feeding. A sheet feeding apparatus comprising: a pickup roller, a knockup plate for loading paper; a feed roller for feeding a paper picked up by said pickup roller; biasing means for urging the knockup plate against the pickup roller and means for moving the knockup plate away from the pickup roller counter to the action of the biasing means; and a document guider for guiding a document in order to engage said feed roller if said document is inserted in the state when said knockup plate is moved away from said pickup roller; characterised in that the means for moving the knockup plate comprises a pickup cam mounted co-axially with the pickup roller for rotation therewith and operatively acting, on rotation of the pickup roller, on the knockup plate to move the knockup plate away from the pickup roller. In a preferred embodiment, said document guider is made of a thin film. In another preferred embodiment, one end of said film is located between said pickup roller and said knockup plate, said film including cut-out portions around the contacting portions of the pickup roller whereby said contacting portions may directly contact paper on said knockup plate. For a better understanding of the invention and to show how the same may be carried into effect, reference will be made, by way of example only, to the following drawings, in which: FIG. 1 shows an example of a document guider according to the present invention. FIG. 2 through FIG. 5 are operational views of a sheet feeder according to the invention. Hereinafter, a preferred embodiment of the present invention will be described with reference to the attached drawings as follows. FIG. 1 shows an example of a document guider according to the present invention, and FIG. 2 through FIG. 5 show the operation views of the feeder according to the invention. For the purpose of the illustrated example, the term "paper" means one or more sheets from a stack of paper loaded in a load cassette for printing, and the term "document" means a document for scanning or a form sheet or others which are not loaded in a general paper cassette. The present invention is therefore particularly advantageous when it is applied to a combination device having both printing functions and scanning functions. Referring now to the drawings, it can be seen that the device of the present invention includes a paper cassette 200 including a knock up plate 220. The knock up plate 220 is urged upwardly by means of a spring or other suitable biasing means 230. A pickup roller 510 is mounted axially transversely with respect to the paper feeding direction and includes idle rollers 520. The outer driving surface of the pick up roller 510 which frictionally engages the paper or document to feed the same covers only a portion of the outer circumference of the roller. In the embodiment illustrated, just over half the outer surface is covered, so that the outer driving surface has a sort of half moon shape. A pickup cam 530 is mounted co-axially with the pickup roller 510. A manual feed part 300 for feeding documents and the like is mounted for rotation about hinge or pivot 310. The manual feed part 300 includes at the end thereof a document guider 320. A finger 430 is provided for separating the papers sheet by sheet. The finger 430 is attached to a torsion spring 440 which acts between the finger and the paper cassette 200. Finger 430 is connected to a finger control part 400 having a first guide 420 and which can rotate about axis 410 As illustrated in FIG. 1, the present invention has a shape in which a plate for manually supplying paper has cut portions of a certain length and a paper or document guider made from a thin film material, whereby when paper on the manual plate is picked up by the pickup roller 510, frictional interaction between any paper on the automatic supplying plate (ie from knock up plate 220) and manually fed paper picked up by the pickup roller is minimised by the paper/document guider which is positioned therebetween. At this time, the document guider 320 is located at the upper of finger 430 for separating papers sheet by sheet during auto feeding. That is, it is located between knockup plate 220, which is a support tray for loading papers, and pickup roller 510 for picking up papers loaded on the knockup plate 220. Also, the document guider is made of film material and can be attached to manual device part 300 by using double sided tape or the like. One end of the paper guider 320 is located between the pickup roller 510 and the knockup plate 220, and the contact parts at which the pickup roller 510 and the knockup plate meet are cut out. Thus, the knockup plate 220 and the pickup roller 510 are formed to contact directly. Fig 2 shows the knock up plate 220 and the manual feed part 300 in a standby state for loading paper onto the knock up plate 220. Manual device part 300 can be rotated counter clockwise from its normal position around hinge 310 in order to facilitate loading paper onto the knock up plate. At this time, thin film document guider 320 which is attached to a part of manual device part 300 is located between the bottom of pickup roller 510 and finger 430. Also, knockup plate 220 is urged towards pickup frame 210 by cam 530, while awaiting loading of paper P, fed automatically Finger 430 is elevated against the bias of finger spring 440 fixed to pickup frame 210. When paper is loaded by the user, and a printing command is ordered for documenting data written by computer, the printer picks up paper which has been loaded on the knockup plate for printing by adopting the automatic feed condition illustrated in Fig 3. That is, half-moon shaped pickup roller 510 rotates clockwise. Thus, pickup cam 530 which in the state illustrated in Fig 2 presses knockup plate 220 downwardly rotates with pickup roller 510 so that knockup plate 220 is elevated by the biasing of the knockup spring 230 and the sheet feeding apparatus arrives at an auto pickup state as in FIG. 3. Therefore, papers picked up by pickup roller 510 are passed between pickup roller 510 and finger 430 and then transmitted for printing. From this state, conversion to manual feeding by a user is achieved by rotating manual device and finger control part 400 is urged by the first guide 420 so that the feeder adopts the manual feed configuration shown in Figure 5. Thus, finger 430 is made to descend and document guider 320 is elevated such that finger 430 which operates in connection with the first guide 420 and torsion spring rotates counter clockwise around rotation axis 410. Also, knock up plate 220 is depressed again by cam 530 on rotation of pickup roller 510. At this state, if a document like a document for scanning or letter sheet is loaded in the manual device part 300, this document is picked up and fed by pickup roller 510, and passed between idle roller 520 and document guider 320 and is fed onwardly. At this time, document guider at upper part of finger 320 helps transmission guide sheet by sheet. FIG. 4 illustrates auto feeding without changing the position of the manual device part. That is, if a paper sheet is inserted into manual device part 300 in auto sheet feeding state, pickup roller picks up the paper sheet. The paper thus fed is passed and fed through the bottom of the thin document guider 320 added to one part of manual device part 300. If a printing operation then starts, pickup roller picks up paper stored in auto-sheet feeding device part, and the document guider added to one part of the manual guider is adjusted upward a little bit by the auto-sheet feeding operation. Therefore, it is possible not to disturb auto sheet feeding and to decrease bad transmission by changing amount of curl or curve deformation on a thin paper of which strength is weak. That is, auto sheet feeding operation is performed without changing a position of manual device part. In the device of the invention in the configuration illustrated in Fig 4, both manual and automatic feeding can be used but, without exception, only one paper is fed at once. As the pickup roller rotates, so does cam 530 so that knock up plate 220 is depressed by cam 530. When the knock up plate is depressed, paper is not picked up from the automatic feed. As described above, the present invention develops user's convenience remarkably by embodying manual feeding and auto feeding at the same time without a conversion from manual feeding to auto feeding, and decreases costs by removing the elemental members like position-detecting and so on for fixing manual feeding device at a regular position. Also, the present invention has an effect of improving printing quality by means that a guide film on the upper of finger affects curl on a paper elastically for auto separation.

Claims: A sheet feeding apparatus comprising: a pickup roller (510); a knockup plate (220)for loading paper (P); a feed roller for feeding a paper (P) picked up by said pickup roller (510); biasing means (230) for urging the knockup plate against the pickup roller (570) and means for moving the knockup plate (220) away from the pickup roller (510) counter to the action of the biasing means (230) ; and a document guider (320) for guiding a document in order to engage said feed roller if said document is inserted in the state when said knockup plate (220) is moved away from said pickup roller (510); characterised in that the means for moving the knockup plate (220) comprises a pickup cam (530) mounted co-axially with the pickup roller (510) for rotation therewith and operatively acting, on rotation of the pickup roller (510), on the knockup plate (220) to move the knockup plate (220) away from the pickup roller (510). The device as claimed in claim 1, wherein said document guider (320) is made of film. The device as claimed in claim 2, wherein one end of said film (320) is located between said pickup roller (510) and said knockup plate (220), said film (320) including cut-out portion around the contacting portions of the pickup roller (510) whereby said contacting portions may directly contact paper on said knockup plate (220).

Inventors: JANG HEUNG-KYU, JANG, HEUNG-KYU
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1998
Main classification: B65H3
IPC codes: B65H3, B41J11