US20050001372A1 - Sheet feeding apparatus and image forming apparatus - Google Patents
Sheet feeding apparatus and image forming apparatus Download PDFInfo
- Publication number
- US20050001372A1 US20050001372A1 US10/878,467 US87846704A US2005001372A1 US 20050001372 A1 US20050001372 A1 US 20050001372A1 US 87846704 A US87846704 A US 87846704A US 2005001372 A1 US2005001372 A1 US 2005001372A1
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- US
- United States
- Prior art keywords
- sheet feeding
- sheet
- sheets
- feeding roller
- separation pad
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H1/00—Supports or magazines for piles from which articles are to be separated
- B65H1/26—Supports or magazines for piles from which articles are to be separated with auxiliary supports to facilitate introduction or renewal of the pile
- B65H1/266—Support fully or partially removable from the handling machine, e.g. cassette, drawer
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/65—Apparatus which relate to the handling of copy material
- G03G15/6555—Handling of sheet copy material taking place in a specific part of the copy material feeding path
- G03G15/6558—Feeding path after the copy sheet preparation and up to the transfer point, e.g. registering; Deskewing; Correct timing of sheet feeding to the transfer point
- G03G15/6561—Feeding path after the copy sheet preparation and up to the transfer point, e.g. registering; Deskewing; Correct timing of sheet feeding to the transfer point for sheet registration
- G03G15/6564—Feeding path after the copy sheet preparation and up to the transfer point, e.g. registering; Deskewing; Correct timing of sheet feeding to the transfer point for sheet registration with correct timing of sheet feeding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H1/00—Supports or magazines for piles from which articles are to be separated
- B65H1/04—Supports or magazines for piles from which articles are to be separated adapted to support articles substantially horizontally, e.g. for separation from top of pile
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H3/00—Separating articles from piles
- B65H3/46—Supplementary devices or measures to assist separation or prevent double feed
- B65H3/52—Friction retainers acting on under or rear side of article being separated
- B65H3/5207—Non-driven retainers, e.g. movable retainers being moved by the motion of the article
- B65H3/5215—Non-driven retainers, e.g. movable retainers being moved by the motion of the article the retainers positioned under articles separated from the top of the pile
- B65H3/5223—Retainers of the pad-type, e.g. friction pads
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/65—Apparatus which relate to the handling of copy material
- G03G15/6555—Handling of sheet copy material taking place in a specific part of the copy material feeding path
- G03G15/6558—Feeding path after the copy sheet preparation and up to the transfer point, e.g. registering; Deskewing; Correct timing of sheet feeding to the transfer point
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2405/00—Parts for holding the handled material
- B65H2405/10—Cassettes, holders, bins, decks, trays, supports or magazines for sheets stacked substantially horizontally
- B65H2405/11—Parts and details thereof
- B65H2405/113—Front, i.e. portion adjacent to the feeding / delivering side
Definitions
- the present invention relates to a sheet feeding apparatus that is provided in an image forming apparatus for forming an image on a recording medium such as an electrophotographic copying machine, a printer, a word processor, or a facsimile apparatus.
- a sheet feeding apparatus for automatically feeding a recording medium (hereinafter referred to as sheet) to an image forming portion is mounted on an image forming apparatus.
- FIGS. 13 to 16 show an example of a conventional image forming apparatus and a sheet feeding apparatus mounted on this image forming apparatus.
- FIG. 13 is a schematic sectional view of a laser beam printer (hereinafter referred to as printer) 1 that is a conventional image forming apparatus.
- printer a laser beam printer
- FIG. 14 is a sectional view of a sheet feeding apparatus mounted on the printer 1
- FIG. 15 is a perspective view of the sheet feeding apparatus
- FIG. 16 is an enlarged view of a separating portion of the sheet feeding apparatus.
- the printer 1 includes: a sheet feeding apparatus 2 ; and a first conveying roller pair 7 and a second conveying roller pair 9 for conveying a sheet P delivered from the sheet feeding apparatus 2 to an image forming portion F.
- the image forming portion F includes: a process cartridge 13 ; a laser scanning optical system 11 for forming an electrostatic latent image on a photosensitive drum 14 that is provided in the process cartridge 13 ; a transferring roller 15 for transferring a toner image that is formed on the photosensitive drum 14 by developing the electrostatic latent image; and a fixing device 17 for fixing the toner image on the sheet having the toner image transferred thereon.
- the transferring roller 15 transfers the toner image, which is formed on the photosensitive drum 14 of the process cartridge 13 , to the sheet P conveyed by the first conveying roller pair 7 and the second conveying roller pair 9 .
- the fixing device 17 fixes the toner image to the sheet P by heating and pressurizing the sheet P having the toner image transferred thereon, thereby performing image formation.
- a delivery roller pair 19 for delivery of the sheet P to which the toner image has been fixed and a delivery tray 21 for stacking and receiving sheets to be delivered.
- the sheet feeding apparatus 2 includes: a sheet feeding roller 4 constituted by a semicircular rubber roller 4 a and a shaft 4 b ; a pair of sheet feeding sub-rollers 23 that are rotatably held by the shaft 4 b and arranged on both sides of the rubber roller 4 a ; and a sheet feeding cassette 3 that houses the sheets P to be supplied to the image forming portion F.
- the sheet feeding cassette 3 includes: a cassette main body 3 a ; a pressure plate 5 serving as pushing means for supporting the sheets P which is rotatably supported by the cassette main body 3 a ; a pressure spring 24 that urges the pressure plate 5 so as to push the leading edge side of the supported sheets P against the sheet feeding roller 4 ; a separation pad 6 for separating the sheets P, which are delivered by the sheet feeding roller, one by one; a separation spring 25 that urges the separation pad 6 toward the sheet feeding roller 4 ; width regulating plates 27 and 28 that regulate a position in a width direction of the sheets P contained in the sheet feeding cassette 3 ; and a trailing edge regulating plate 29 that regulates a position of a trailing edge of the sheets P.
- the width regulating plates 27 and 28 provided in the sheet feeding cassette 3 are provided so as to be movable in a width direction of sheets according to a size of the sheets in the sheet feeding cassette 3 in order to regulate a sheet width of the sheets P.
- the trailing edge regulating plate 29 is provided so as to be movable in the longitudinal direction of the sheets according to the size of the sheets.
- the separation pad 6 is constituted by a rubber material 6 a , which comes into abutment against the sheet feeding roller 4 , and a holder 6 b , which is rotatably held by the cassette body 3 a that holds the rubber material 6 a .
- the separation pad 6 is urged by the separation spring 25 such that the rubber material 6 a is brought into press-contact with the sheet feeding roller 4 .
- the separation pad 6 comes into abutment against outer peripheral surfaces of the sheet feeding sub-rollers 23 in a sheet feed standby state, and is pushed against the outer peripheral surfaces of the sheet feeding sub-rollers 23 through the sheet P during conveyance of the sheet P.
- the conventional sheet feeding apparatus disclosed in Japanese Patent Application Laid-Open No. 08-157110 has a problem in that a trailing edge of a sheet that is fed after being separated jumps as the sheet passes through the separation pad, thus generating noise.
- the technique disclosed in the laid-open patent application only addresses the problem of trailing edge jumping sound that is caused as the trailing edge of the separated sheet jumps after passing through a press-contact portion between the sheet feeding roller and the separation pad.
- the technique does not address the problem of trailing edge jumping sound that is caused when the trailing edge of the separated sheet moves away from a sheet stacking portion.
- an abutting portion N 2 where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, is arranged adjacent to a pushing portion N where the sheets P are pushed against the sheet feeding roller 4 by the pressure plate 5 (abutting portion where the sheet feeding roller 4 and the sheet P come into abutment against each other) and on the downstream side with respect to the sheet conveying direction.
- a trailing edge P 1 of the sheets P to be fed jumps in a direction of arrow A immediately after passing through the pushing portion where the sheets P are pushed against the sheet feeding roller 4 by the pressure plate 5 , and hits the separation pad 6 to generate trailing edge jumping sound.
- this trailing edge jumping sound becomes more noticeable with a stiff sheet such as thick sheet, causing deterioration in the noise level of the printer 1 .
- the present invention has been devised in order to solve the above-mentioned problems, and it is an object of the present invention to realize a sheet feeding apparatus with reduced noise and provide an image forming apparatus capable of silent operation.
- a sheet feeding apparatus characterized by including: sheet housing means for housing sheets; a sheet feeding roller for feeding the sheets housed in the sheet housing means; pushing means for pushing the sheets against the sheet feeding roller; a separation pad that comes into abutment against the sheet feeding roller and separates the sheets one by one as the sheets are fed by the sheet feeding roller and the pushing means; and a sheet guide portion that is arranged between a pushing portion where the sheets are pushed against the sheet feeding roller by the pushing means and an abutting portion where the sheet feeding roller and the separation pad come into abutment against each other.
- FIG. 1 is a schematic sectional view of an image forming apparatus including a sheet feeding apparatus in accordance with a first embodiment of the present invention
- FIG. 2 is a schematic sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention
- FIG. 3 is a perspective view of a sheet feeding cassette included in the sheet feeding apparatus in accordance with the first embodiment of the present invention
- FIG. 4A is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment in a state where the sheet feeding apparatus is fully loaded with sheets;
- FIG. 4B is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention in a state where the sheet feeding apparatus is loaded with a small amount of sheets;
- FIG. 5 is a partial sectional view showing attachment angles of respective members of the sheet feeding apparatus in accordance with the first embodiment of the present invention
- FIG. 6 is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention in a sheet feeding operation
- FIG. 7 is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention in a conveying operation
- FIG. 8 is a schematic sectional view of a sheet feeding apparatus in accordance with a second embodiment of the present invention.
- FIG. 9 is a perspective view of a sheet feeding cassette included in the sheet feeding apparatus in accordance with the second embodiment of the present invention.
- FIG. 10 is a partial sectional view of a sheet feeding apparatus in accordance with a third embodiment of the present invention.
- FIG. 11 is a partial sectional view of a sheet feeding apparatus in accordance with a fourth embodiment of the present invention.
- FIG. 12 is a perspective view of a sheet feeding cassette included in the sheet feeding apparatus in accordance with the fourth embodiment of the present invention.
- FIG. 13 is a schematic sectional view of an image forming apparatus including a conventional sheet feeding apparatus
- FIG. 14 is a schematic sectional view of the conventional sheet feeding apparatus
- FIG. 15 is a schematic perspective view of the conventional sheet feeding apparatus.
- FIG. 16 is a view for explaining a problem of the conventional sheet feeding apparatus.
- a first embodiment of a sheet feeding apparatus of the present invention will be explained below with a laser beam printer, which is an image forming apparatus adopting an electrophotographic system, as an example.
- FIG. 1 is a sectional view of a laser beam printer (hereinafter referred to as printer) 1 .
- FIG. 2 is a sectional view of a sheet feeding apparatus mounted on this printer 1 .
- FIG. 3 is a perspective view of a sheet feeding cassette that is mounted on the sheet feeding apparatus shown in FIG. 1 . A structure of the printer 1 will be explained with reference to these figures.
- an image forming portion F includes: a process cartridge 13 that is constituted by a photosensitive member 14 , and a developing device, a cleaner, a charging roller, and the like, which are not shown in the figure; a transferring roller 15 that transfers a visualized image on the photosensitive member 14 onto a sheet P; and a fixing device 17 that heats and fixes the visualized image on the sheet P.
- reference numeral 16 denotes a conveyance guide that guides the sheet P to which the image has been transferred to the fixing device 17 .
- the laser scanner 11 is arranged so as to be slanted upward to the right from a scanner polygon 11 a .
- it is most effective to cause a laser beam to be incident on the photosensitive member 14 with a return mirror 12 from a direction substantially perpendicular to a horizontal conveying path for sheets extending from the transferring roller 15 to the fixing device 17 as shown in FIG. 1 .
- Such a structure makes it possible to keep a depth and a height of the printer 1 within minimum dimensions.
- the sheet feeding cassette 3 is arranged in a lower part of a main body of an image forming apparatus (hereinafter referred to as printer main body) 1 a .
- a delivery tray 21 is formed integrally with an outer cover 20 in an upper part of the printer body 1 a .
- the sheet feeding cassette 3 and the delivery tray 21 are coupled to each other by a sheet conveying path including the image forming portion F.
- This sheet conveying path constitutes an S-shaped path as a whole.
- the sheet feeding cassette 3 is arranged in the lower part of the printer body 1 a , and the delivery tray 21 is arranged in the upper part of the printer body 1 a to form the S-shaped sheet conveying path in this way, whereby the printer 1 is made compact to reduce an installation area.
- a sheet delivered from the sheet feeding cassette 3 is sent to the image forming portion F by a curved sheet conveying path 8 .
- a first conveying roller pair 7 and a second conveying roller pair 9 are arranged in the sheet conveying path 8 , and the sheet is conveyed to the image forming portion F by these sheet conveying roller pairs 7 and 9 .
- a direction of a nip line thereof (a tangent of a press-contact portion of a roller) is a vertical direction.
- the first conveying roller pair 7 conveys a sheet delivered from a sheet feeding apparatus 2 , which will be described later in detail, in the vertical direction.
- the sheet to be conveyed is guided to the second conveying roller pair 9 by the curved sheet conveying path 8 .
- Reference numeral 10 denotes a registration sensor. This registration sensor 10 synchronizes a leading edge position of a sheet P, which is conveyed by the sheet conveying roller pairs 7 and 9 , with light-emitting timing of the laser scanner 11 serving as an exposure light source and starts drawing an image from a predetermined position on the sheet P.
- a sheet discharge sensor 18 for detecting a leading edge position and a trailing edge position of the sheet P, which has been heated and fixed by the fixing device 17 , and detecting jam is provided in a sheet conveying path 8 on a downstream side of the image forming portion F.
- a sheet discharge roller pair 19 for delivery of the sheet P onto a delivery tray 21 is provided on a downstream-side end of the sheet conveying path 8 B.
- Reference numeral 22 denotes an electrical portion consisting of an AC power supply and a DC power supply, and a high voltage power supply. As shown in FIG. 1 , the electrical portion 22 is arranged below a horizontal conveying path extending from the transferring roller 15 to the fixing device 17 and above the sheet feeding cassette 3 , whereby the space of the printer body 1 a is used efficiently to prevent an increase in installation area due to the electrical portion 22 . In addition, by arranging the electrical portion 22 below the horizontal conveying path extending from the transferring roller 15 to the fixing device 17 , bundle wires necessary for electrical connection of the transferring roller 15 and the fixing device 17 can be simplified.
- the sheet feeding apparatus 2 includes: a sheet feeding portion 2 a that is provided in the printer body 1 a ; and a sheet feeding cassette 3 that houses sheets to be delivered by the sheet feeding portion 2 a .
- the sheet feeding portion 2 a includes: a sheet feeding roller 4 , which is constituted by a semicircular rubber roller 4 a and a shaft 4 a , attached to the printer body 1 a ; and sheet feeding sub-rollers 23 that are rotatably held by the shaft 4 b and arranged on both sides of the rubber roller 4 a .
- the sheet feeding sub-rollers 23 are set to have an outer diameter smaller than a maximum outer diameter of the semicircular rubber roller 4 a.
- the sheet feeding cassette 3 for housing the sheets P includes: a pressure plate 5 serving as pushing means for pushing a leading edge side of the housed sheets P against the sheet feeding roller 4 ; a pressure spring 24 that urges the pressure plate 5 upward; width regulating plates 27 and 28 that regulate a position in a width direction of the sheets P stacked on the pressure plate 5 ; and a trailing edge regulating plate 29 that regulates a trailing edge position of the sheets P.
- the width regulating plates 27 and 28 are movable in a width direction of the sheets P according to a size of the sheets P in order to regulate a width of the sheets P, and the trailing edge regulating plate 29 is movable in a length direction of the sheets P according to the size of the sheets P.
- the sheet feeding cassette 3 includes: a separation pad 6 for separating the sheets P, which are delivered by the sheet feeding roller 4 , one by one; and a separation spring 25 that urges the separation pad 6 to the sheet feeding roller 4 .
- a sheet guide surface 26 which guides the sheets P delivered by the sheet feeding roller 4 toward the abutting portion N 2 , is formed integrally with a cassette body 3 a.
- the pressure plate 5 is held in the sheet feeding cassette 3 so as to be rotatable about a rotation center 5 A and pushes the leading edge side of the sheets P against the sheet feeding sub-rollers 23 by a spring force of the pressure spring 24 in a sheet feed standby state.
- a separation sheet 30 (shown in FIG. 3 ) is provided in a part of the pressure plate 5 opposed to the sheet feeding roller 4 .
- the separation sheet 30 consists of cork, synthetic resin, or the like and prevents double feeding of the lowermost sheet P stacked on the sheet feeding cassette 3 .
- the separation pad 6 consists of a rubber material 6 a , which comes into abutment against the sheet feeding roller 4 , and a holder 6 b , which holds the rubber material 6 a .
- the separation pad 6 comes into abutment against the sheet feeding sub-rollers 23 in a sheet feed standby state, and is pushed against the sheet feeding sub-rollers 23 through the sheet P during conveyance of the sheets P fed to the sheet conveying path 8 by the sheet feeding roller 4 .
- the separation pad 6 and the separation spring 25 which urges the separation pad 6 , are provided in the cassette body 3 a.
- the sheet feeding cassette 3 is detachably mounted on the printer body 1 a . Thus, when the sheets P are supplied, the sheet feeding cassette 3 can be removed from the image forming apparatus body 1 a to perform supply of additional sheets.
- FIG. 4A is a partial sectional view of a sheet feeding apparatus at the time when the sheet feeding apparatus is fully loaded with the sheets P.
- FIG. 4B is a partial sectional view of the sheet feeding apparatus at the time when the sheet feeding apparatus is loaded with a small amount of the sheets P.
- a tangent B of the sheet feeding roller 4 in the pushing portion N 1 and a sheet top surface P 2 in FIG. 4A coincide with each other.
- a tangent C of the sheet feeding roller 4 in the pushing portion N 1 and a sheet top surface P 3 in FIG. 4B coincide with each other.
- the pressure plate 5 is arranged such that a tangent direction of the sheet feeding roller 4 in the pushing portion N 1 and a top surface of sheets coincide with each other regardless of the amount of stacked sheets P.
- Table 1 shows a result of an experiment in which the angles ⁇ and ⁇ are changed. As it is seen from this result, by setting the angles ⁇ and ⁇ to 110° ⁇ 135° and 170° ⁇ 175°, satisfactory sheet feeding performance is obtained with thin sheet (60 g sheet) and thick sheet (163 g sheet). When the angles ⁇ and ⁇ are reduced, a conveying resistance at a leading edge of the sheet P to be fed increases to cause defective sheet feeding. In addition, when the angles ⁇ and ⁇ are increased, this results in reduced leading-edge separating action for the sheets P to cause double feeding.
- the coefficients of friction are set so as to satisfy a relation of ⁇ 1 ⁇ 2 ⁇ 3.
- the coefficient of friction ⁇ 1 between the sheet guide surface 26 and the sheet P is set to about 0.1 to 0.2
- the coefficient of friction ⁇ 2 between the separation pad 6 and the sheet P is set to about 0.7 to 1.0
- the coefficient of friction ⁇ 3 between the sheet feeding roller 4 and the sheet P is set to about 1.5 to 2.0.
- FIG. 6 is a partial sectional view of the sheet feeding apparatus in a sheet feeding operation.
- FIG. 7 is a partial sectional view of the sheet feeding apparatus in a conveying operation.
- the sheet feeding roller 4 receives transmission of a drive force from a drive source such as a motor (not shown in the figure) and rotates in a direction of arrow D in FIG. 6 . Then, of the sheets P pushed against the sheet feeding roller 4 by the pressure plate 5 due to the force of the pressure spring 24 , a few sheets P at the top including the one brought into abutment against the sheet feeding roller 4 are conveyed by the sheet feeding roller 4 .
- a drive source such as a motor (not shown in the figure)
- a leading edge P 4 of the sheets P conveyed by the sheet feeding roller 4 are handled on the sheet guide surface 26 , which is formed as an inclined surface inclined toward the abutting portion N 2 where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, whereby the sheets P are subjected to a separating action and separated (hereinafter referred to as first separation).
- the sheets P which could not be separated on the sheet guide surface 26 , are separated in the abutting portion N 2 where the rubber material 6 a of the separation pad 6 and the sheet feeding roller 4 come into abutment against each other, (hereinafter referred to as second separation) to send only one sheet, which is in abutment against the sheet feeding roller 4 , to the sheet conveying path 8 so as to be fed to the first conveying roller pair 7 .
- the sheet feeding roller 4 makes one revolution and stops at a standby position
- the sheet P conveyed by the first conveying roller pair 7 is conveyed while being brought into abutment against the sheet feeding sub-rollers 23 by a pushing force of the pressure plate 5 and the separation pad 6 .
- a trailing edge P 5 of the sheet P is led to the abutting portion N 2 where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, while being guided by the sheet guide surface 26 .
- the trailing edge P 5 of the sheet P is led to the abutting portion N 2 where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, while being guided by the sheet guide surface 26 .
- the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, while being guided by the sheet guide surface 26 .
- the sheets P are subjected to separating actions in two stages consisting of the first separation for handling and separating the sheets P on the sheet guide surface 26 formed as an inclined surface and the second separation for separating the sheets P in the abutting portion N 2 where the rubber material 6 a of the separation pad 6 and the sheet feeding roller 4 come into abutment against each other.
- the double feeding preventing effect is improved.
- a sheet is delivered from the sheet feeding cassette 3 substantially in a vertical direction.
- the sheets which are housed horizontally, are rapidly oriented upward and fed in the separating portion of the sheet feeding roller 4 and the separation pad 6 and passed to the sheet conveying path 8 arranged in a vertical direction.
- the horizontally supported sheets can be delivered in the vertical direction, a size in the horizontal direction of the sheet feeding apparatus can be suppressed to realize a reduction in the size of the printer 1 .
- FIGS. 8 and 9 a second embodiment of the sheet feeding apparatus in accordance with the present invention will be explained with reference to FIGS. 8 and 9 . Note that only structures and operations different from those in the first embodiment will be explained. The other structures and operations are the same as those in the first embodiment.
- FIG. 8 is a sectional view of a sheet feeding apparatus 2 in accordance with the second embodiment.
- FIG. 9 is a perspective view of a sheet feeding cassette 3 that is mounted on this sheet feeding apparatus.
- the inclined guide surface 26 which is provided between the pushing portion N 1 where the sheets P are pushed against the sheet feeding roller 4 by the pressure plate 5 and the abutting portion N 2 where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, and which guides the sheets P delivered by the sheet feeding roller 4 toward the abutting portion N 2 , is formed integrally with the holder 6 b of the separation pad 6 .
- the sheets P are subjected to separating actions in two stages consisting of the first separation for handling and separating the sheets P on the sheet guide surface 26 formed in a slope shape and the second separation for separating the sheets P in the abutting portion N 2 where the rubber material 6 a of the separation pad 6 and the sheet feeding roller 4 come into abutment against each other.
- FIG. 10 is a main part sectional view of the sheet feeding apparatus in accordance with the third embodiment. Only structures and operations different from those of the first and the second embodiments will be described. The other structures and operations are the same as those in the first and the second embodiments.
- the sheet guide surface 26 is formed in an arc shape with an inner diameter surface thereof serving as a sheet guide.
- the sheet guide surface 26 is provided between the pushing portion N 1 , where the sheets P are pushed against the sheet feeding roller 4 by the pressure plate 5 , and the abutting portion N 2 , where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, and guides the sheets P delivered by the sheet feeding roller 4 toward the abutting portion N 2 .
- a separating action acts on the sheets P, which are conveyed by the sheet feeding roller 4 , at a curvature on the sheet guide surface 26 formed in an arc shape toward the abutting portion N 2 where the sheet feeding roller 4 and the separation pad 6 come into abutment against each other, and the sheets P are subjected to the first separation.
- the sheets P which could not be separated on the sheet guide 26 are subjected to the second separation in the abutting portion N 2 , where the rubber material 6 a of the separation pad 6 and the sheet feeding roller 4 come into abutment against each other, to send only one sheet, which is in abutment against the sheet feeding roller 4 , to the sheet conveying path 8 so as to be fed to the first conveying roller pair 7 .
- the sheets P are subjected to separating actions in two stages consisting of the first separation for separating the sheets P at a curvature on the sheet guide surface 26 formed in an arc shape and the second separation for separating the sheets P in the abutting portion N 2 where the rubber material 6 a of the separation pad 6 and the sheet feeding roller 4 come into abutment against each other.
- the double feeding preventing effect is improved.
- FIG. 11 is a sectional view of the sheet feeding apparatus in accordance with the fourth embodiment.
- FIG. 12 is a perspective view of a sheet feeding cassette to be mounted on the sheet feeding apparatus. Only structures and operations different from those in the first to the third embodiments will be explained. The other structures and operations are the same as those in the first to the third embodiments.
- the sheet guide surface 26 is constituted by a tabular member of metal, fixed to the sheet feeding cassette 3 by fixing means such as screws or fitting, and grounded. Since the sheet guide surface 26 is constituted by the tabular member of metal and grounded in this way, there is an effect in that wear of the sheet guide surface 26 due to conveyance and sliding of the sheet P is prevented and occurrence of defective sheet feeding and double feeding due to the wear of the sheet guide surface 26 is prevented. In addition, since charging due to sliding of the sheet P and the sheet guide surface 26 can be prevented, there is an effect in that a defective image due to charging is prevented.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Sheets, Magazines, And Separation Thereof (AREA)
- Paper Feeding For Electrophotography (AREA)
Abstract
A sheet feeding apparatus includes: a sheet containing device for housing sheets; a sheet feeding roller that feed the sheets contained in the sheet containing device; a pushing member for pushing the sheets contained in the sheet containing device against the sheet feeding roller; a separation pad which is provided so as to be capable of abutting against the sheet feeding roller and separates the sheets one by one as the sheets are fed by the sheet feeding roller and the pushing member; and a sheet guide portion arranged between a pushing portion where the sheets are pushed against the sheet feeding roller by the pushing member and an abutting portion where the sheet feeding roller and the separation pad come into abutment against each other. As a result, a sheet feeding apparatus with reduced noise can be realized. In addition, an image forming apparatus with silent operation can be realized by using the sheet feeding apparatus.
Description
- This application claims priority from Japanese Patent Application No. 2003-190395 filed on Jul. 2, 2003, which is hereby incorporated by reference.
- 1. Field of the Invention
- The present invention relates to a sheet feeding apparatus that is provided in an image forming apparatus for forming an image on a recording medium such as an electrophotographic copying machine, a printer, a word processor, or a facsimile apparatus.
- 2. Related Background Art
- A sheet feeding apparatus for automatically feeding a recording medium (hereinafter referred to as sheet) to an image forming portion is mounted on an image forming apparatus. FIGS. 13 to 16 show an example of a conventional image forming apparatus and a sheet feeding apparatus mounted on this image forming apparatus.
-
FIG. 13 is a schematic sectional view of a laser beam printer (hereinafter referred to as printer) 1 that is a conventional image forming apparatus.FIG. 14 is a sectional view of a sheet feeding apparatus mounted on the printer 1,FIG. 15 is a perspective view of the sheet feeding apparatus, andFIG. 16 is an enlarged view of a separating portion of the sheet feeding apparatus. - In
FIG. 13 , the printer 1 includes: asheet feeding apparatus 2; and a firstconveying roller pair 7 and a secondconveying roller pair 9 for conveying a sheet P delivered from thesheet feeding apparatus 2 to an image forming portion F. The image forming portion F includes: aprocess cartridge 13; a laser scanningoptical system 11 for forming an electrostatic latent image on aphotosensitive drum 14 that is provided in theprocess cartridge 13; a transferringroller 15 for transferring a toner image that is formed on thephotosensitive drum 14 by developing the electrostatic latent image; and afixing device 17 for fixing the toner image on the sheet having the toner image transferred thereon. - The transferring
roller 15 transfers the toner image, which is formed on thephotosensitive drum 14 of theprocess cartridge 13, to the sheet P conveyed by the firstconveying roller pair 7 and the secondconveying roller pair 9. Thefixing device 17 fixes the toner image to the sheet P by heating and pressurizing the sheet P having the toner image transferred thereon, thereby performing image formation. - Provided on the downstream side of the
fixing device 17 are adelivery roller pair 19 for delivery of the sheet P to which the toner image has been fixed and a delivery tray 21 for stacking and receiving sheets to be delivered. - In
FIGS. 14 and 15 , thesheet feeding apparatus 2 includes: asheet feeding roller 4 constituted by asemicircular rubber roller 4 a and ashaft 4 b; a pair ofsheet feeding sub-rollers 23 that are rotatably held by theshaft 4 b and arranged on both sides of therubber roller 4 a; and asheet feeding cassette 3 that houses the sheets P to be supplied to the image forming portion F. - The
sheet feeding cassette 3 includes: a cassettemain body 3 a; apressure plate 5 serving as pushing means for supporting the sheets P which is rotatably supported by the cassettemain body 3 a; apressure spring 24 that urges thepressure plate 5 so as to push the leading edge side of the supported sheets P against thesheet feeding roller 4; aseparation pad 6 for separating the sheets P, which are delivered by the sheet feeding roller, one by one; aseparation spring 25 that urges theseparation pad 6 toward thesheet feeding roller 4;width regulating plates sheet feeding cassette 3; and a trailingedge regulating plate 29 that regulates a position of a trailing edge of the sheets P. - The width regulating
plates sheet feeding cassette 3 are provided so as to be movable in a width direction of sheets according to a size of the sheets in thesheet feeding cassette 3 in order to regulate a sheet width of the sheets P. The trailingedge regulating plate 29 is provided so as to be movable in the longitudinal direction of the sheets according to the size of the sheets. - The
separation pad 6 is constituted by arubber material 6 a, which comes into abutment against thesheet feeding roller 4, and aholder 6 b, which is rotatably held by thecassette body 3 a that holds therubber material 6 a. Theseparation pad 6 is urged by theseparation spring 25 such that therubber material 6 a is brought into press-contact with thesheet feeding roller 4. Theseparation pad 6 comes into abutment against outer peripheral surfaces of thesheet feeding sub-rollers 23 in a sheet feed standby state, and is pushed against the outer peripheral surfaces of thesheet feeding sub-rollers 23 through the sheet P during conveyance of the sheet P. - However, the conventional sheet feeding apparatus disclosed in Japanese Patent Application Laid-Open No. 08-157110 has a problem in that a trailing edge of a sheet that is fed after being separated jumps as the sheet passes through the separation pad, thus generating noise. In order to solve this problem, there is a technique for providing wing portions at both ends of the separation pad in a direction perpendicular to a sheet conveying direction.
- However, the technique disclosed in the laid-open patent application only addresses the problem of trailing edge jumping sound that is caused as the trailing edge of the separated sheet jumps after passing through a press-contact portion between the sheet feeding roller and the separation pad. The technique does not address the problem of trailing edge jumping sound that is caused when the trailing edge of the separated sheet moves away from a sheet stacking portion.
- That is, in the sheet feeding apparatus shown in
FIG. 16 , an abutting portion N2, where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, is arranged adjacent to a pushing portion N where the sheets P are pushed against thesheet feeding roller 4 by the pressure plate 5 (abutting portion where thesheet feeding roller 4 and the sheet P come into abutment against each other) and on the downstream side with respect to the sheet conveying direction. A trailing edge P1 of the sheets P to be fed jumps in a direction of arrow A immediately after passing through the pushing portion where the sheets P are pushed against thesheet feeding roller 4 by thepressure plate 5, and hits theseparation pad 6 to generate trailing edge jumping sound. In particular, this trailing edge jumping sound becomes more noticeable with a stiff sheet such as thick sheet, causing deterioration in the noise level of the printer 1. Thus, it is necessary to reduce the trailing edge jumping sound for the purpose of achieving a silent operation. - The present invention has been devised in order to solve the above-mentioned problems, and it is an object of the present invention to realize a sheet feeding apparatus with reduced noise and provide an image forming apparatus capable of silent operation.
- To attain the above object, according to the present invention, there is provided a sheet feeding apparatus characterized by including: sheet housing means for housing sheets; a sheet feeding roller for feeding the sheets housed in the sheet housing means; pushing means for pushing the sheets against the sheet feeding roller; a separation pad that comes into abutment against the sheet feeding roller and separates the sheets one by one as the sheets are fed by the sheet feeding roller and the pushing means; and a sheet guide portion that is arranged between a pushing portion where the sheets are pushed against the sheet feeding roller by the pushing means and an abutting portion where the sheet feeding roller and the separation pad come into abutment against each other.
-
FIG. 1 is a schematic sectional view of an image forming apparatus including a sheet feeding apparatus in accordance with a first embodiment of the present invention; -
FIG. 2 is a schematic sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention; -
FIG. 3 is a perspective view of a sheet feeding cassette included in the sheet feeding apparatus in accordance with the first embodiment of the present invention; -
FIG. 4A is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment in a state where the sheet feeding apparatus is fully loaded with sheets; -
FIG. 4B is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention in a state where the sheet feeding apparatus is loaded with a small amount of sheets; -
FIG. 5 is a partial sectional view showing attachment angles of respective members of the sheet feeding apparatus in accordance with the first embodiment of the present invention; -
FIG. 6 is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention in a sheet feeding operation; -
FIG. 7 is a partial sectional view of the sheet feeding apparatus in accordance with the first embodiment of the present invention in a conveying operation; -
FIG. 8 is a schematic sectional view of a sheet feeding apparatus in accordance with a second embodiment of the present invention; -
FIG. 9 is a perspective view of a sheet feeding cassette included in the sheet feeding apparatus in accordance with the second embodiment of the present invention; -
FIG. 10 is a partial sectional view of a sheet feeding apparatus in accordance with a third embodiment of the present invention; -
FIG. 11 is a partial sectional view of a sheet feeding apparatus in accordance with a fourth embodiment of the present invention; -
FIG. 12 is a perspective view of a sheet feeding cassette included in the sheet feeding apparatus in accordance with the fourth embodiment of the present invention; -
FIG. 13 is a schematic sectional view of an image forming apparatus including a conventional sheet feeding apparatus; -
FIG. 14 is a schematic sectional view of the conventional sheet feeding apparatus; -
FIG. 15 is a schematic perspective view of the conventional sheet feeding apparatus; and -
FIG. 16 is a view for explaining a problem of the conventional sheet feeding apparatus. - First Embodiment
- A first embodiment of a sheet feeding apparatus of the present invention will be explained below with a laser beam printer, which is an image forming apparatus adopting an electrophotographic system, as an example.
-
FIG. 1 is a sectional view of a laser beam printer (hereinafter referred to as printer) 1.FIG. 2 is a sectional view of a sheet feeding apparatus mounted on this printer 1.FIG. 3 is a perspective view of a sheet feeding cassette that is mounted on the sheet feeding apparatus shown inFIG. 1 . A structure of the printer 1 will be explained with reference to these figures. - (Image Forming Portion)
- In
FIG. 1 , an image forming portion F includes: aprocess cartridge 13 that is constituted by aphotosensitive member 14, and a developing device, a cleaner, a charging roller, and the like, which are not shown in the figure; a transferringroller 15 that transfers a visualized image on thephotosensitive member 14 onto a sheet P; and a fixingdevice 17 that heats and fixes the visualized image on the sheet P. Note that reference numeral 16 denotes a conveyance guide that guides the sheet P to which the image has been transferred to the fixingdevice 17. - (Laser Scanner)
- As shown in
FIG. 1 , thelaser scanner 11 is arranged so as to be slanted upward to the right from ascanner polygon 11 a. Here, in order to reduce a size of the printer 1 as much as possible, it is most effective to cause a laser beam to be incident on thephotosensitive member 14 with areturn mirror 12 from a direction substantially perpendicular to a horizontal conveying path for sheets extending from the transferringroller 15 to the fixingdevice 17 as shown inFIG. 1 . Such a structure makes it possible to keep a depth and a height of the printer 1 within minimum dimensions. - (Sheet Conveying Path)
- As shown in
FIG. 1 , thesheet feeding cassette 3 is arranged in a lower part of a main body of an image forming apparatus (hereinafter referred to as printer main body) 1 a. Adelivery tray 21 is formed integrally with anouter cover 20 in an upper part of theprinter body 1 a. Thesheet feeding cassette 3 and thedelivery tray 21 are coupled to each other by a sheet conveying path including the image forming portion F. This sheet conveying path constitutes an S-shaped path as a whole. Thesheet feeding cassette 3 is arranged in the lower part of theprinter body 1 a, and thedelivery tray 21 is arranged in the upper part of theprinter body 1 a to form the S-shaped sheet conveying path in this way, whereby the printer 1 is made compact to reduce an installation area. - A sheet delivered from the
sheet feeding cassette 3 is sent to the image forming portion F by a curvedsheet conveying path 8. A first conveyingroller pair 7 and a second conveyingroller pair 9 are arranged in thesheet conveying path 8, and the sheet is conveyed to the image forming portion F by these sheet conveying roller pairs 7 and 9. In the first conveyingroller pair 7, a direction of a nip line thereof (a tangent of a press-contact portion of a roller) is a vertical direction. The first conveyingroller pair 7 conveys a sheet delivered from asheet feeding apparatus 2, which will be described later in detail, in the vertical direction. The sheet to be conveyed is guided to the second conveyingroller pair 9 by the curvedsheet conveying path 8. -
Reference numeral 10 denotes a registration sensor. Thisregistration sensor 10 synchronizes a leading edge position of a sheet P, which is conveyed by the sheet conveying roller pairs 7 and 9, with light-emitting timing of thelaser scanner 11 serving as an exposure light source and starts drawing an image from a predetermined position on the sheet P. - A
sheet discharge sensor 18 for detecting a leading edge position and a trailing edge position of the sheet P, which has been heated and fixed by the fixingdevice 17, and detecting jam is provided in asheet conveying path 8 on a downstream side of the image forming portion F. In addition, a sheetdischarge roller pair 19 for delivery of the sheet P onto adelivery tray 21 is provided on a downstream-side end of thesheet conveying path 8B. - (Electrical Components Layout)
-
Reference numeral 22 denotes an electrical portion consisting of an AC power supply and a DC power supply, and a high voltage power supply. As shown inFIG. 1 , theelectrical portion 22 is arranged below a horizontal conveying path extending from the transferringroller 15 to the fixingdevice 17 and above thesheet feeding cassette 3, whereby the space of theprinter body 1 a is used efficiently to prevent an increase in installation area due to theelectrical portion 22. In addition, by arranging theelectrical portion 22 below the horizontal conveying path extending from the transferringroller 15 to the fixingdevice 17, bundle wires necessary for electrical connection of the transferringroller 15 and the fixingdevice 17 can be simplified. - (Sheet Feeding Apparatus)
- In
FIGS. 2 and 3 , thesheet feeding apparatus 2 includes: asheet feeding portion 2 a that is provided in theprinter body 1 a; and asheet feeding cassette 3 that houses sheets to be delivered by thesheet feeding portion 2 a. Thesheet feeding portion 2 a includes: asheet feeding roller 4, which is constituted by asemicircular rubber roller 4 a and ashaft 4 a, attached to theprinter body 1 a; andsheet feeding sub-rollers 23 that are rotatably held by theshaft 4 b and arranged on both sides of therubber roller 4 a. Thesheet feeding sub-rollers 23 are set to have an outer diameter smaller than a maximum outer diameter of thesemicircular rubber roller 4 a. - The
sheet feeding cassette 3 for housing the sheets P includes: apressure plate 5 serving as pushing means for pushing a leading edge side of the housed sheets P against thesheet feeding roller 4; apressure spring 24 that urges thepressure plate 5 upward;width regulating plates pressure plate 5; and a trailingedge regulating plate 29 that regulates a trailing edge position of the sheets P. Thewidth regulating plates edge regulating plate 29 is movable in a length direction of the sheets P according to the size of the sheets P. - Moreover, the
sheet feeding cassette 3 includes: aseparation pad 6 for separating the sheets P, which are delivered by thesheet feeding roller 4, one by one; and aseparation spring 25 that urges theseparation pad 6 to thesheet feeding roller 4. Between a pushing portion N1 where the sheets P are pushed against thesheet feeding roller 4 by the pressure plate 5 (abutting portion where the sheet P and thesheet feeding roller 4 come into abutment against each other) and an abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, asheet guide surface 26, which guides the sheets P delivered by thesheet feeding roller 4 toward the abutting portion N2, is formed integrally with acassette body 3 a. - The
pressure plate 5 is held in thesheet feeding cassette 3 so as to be rotatable about a rotation center 5A and pushes the leading edge side of the sheets P against thesheet feeding sub-rollers 23 by a spring force of thepressure spring 24 in a sheet feed standby state. A separation sheet 30 (shown inFIG. 3 ) is provided in a part of thepressure plate 5 opposed to thesheet feeding roller 4. Theseparation sheet 30 consists of cork, synthetic resin, or the like and prevents double feeding of the lowermost sheet P stacked on thesheet feeding cassette 3. - The
separation pad 6 consists of arubber material 6 a, which comes into abutment against thesheet feeding roller 4, and aholder 6 b, which holds therubber material 6 a. Theseparation pad 6 comes into abutment against thesheet feeding sub-rollers 23 in a sheet feed standby state, and is pushed against thesheet feeding sub-rollers 23 through the sheet P during conveyance of the sheets P fed to thesheet conveying path 8 by thesheet feeding roller 4. Theseparation pad 6 and theseparation spring 25, which urges theseparation pad 6, are provided in thecassette body 3 a. - The
sheet feeding cassette 3 is detachably mounted on theprinter body 1 a. Thus, when the sheets P are supplied, thesheet feeding cassette 3 can be removed from the image formingapparatus body 1 a to perform supply of additional sheets. -
FIG. 4A is a partial sectional view of a sheet feeding apparatus at the time when the sheet feeding apparatus is fully loaded with the sheets P.FIG. 4B is a partial sectional view of the sheet feeding apparatus at the time when the sheet feeding apparatus is loaded with a small amount of the sheets P. - A tangent B of the
sheet feeding roller 4 in the pushing portion N1 and a sheet top surface P2 inFIG. 4A coincide with each other. In addition, a tangent C of thesheet feeding roller 4 in the pushing portion N1 and a sheet top surface P3 inFIG. 4B coincide with each other. In this way, thepressure plate 5 is arranged such that a tangent direction of thesheet feeding roller 4 in the pushing portion N1 and a top surface of sheets coincide with each other regardless of the amount of stacked sheets P. - In
FIG. 5 , when it is assumed that an angle formed by the tangent (nip line) B of thesheet feeding roller 4 in the pushing portion N1 and thesheet guide surface 26 is a, and an angle formed by a tangent (nip line) of thesheet feeding roller 4 in the abutting portion N2 and thesheet guide surface 26 is β, the angles α and β are set so as to satisfy the following two expressions.
110°≦α≦135°
170°≦β≦175° - Table 1 shows a result of an experiment in which the angles α and β are changed. As it is seen from this result, by setting the angles α and β to 110°≦α≦135° and 170°≦β≦175°, satisfactory sheet feeding performance is obtained with thin sheet (60 g sheet) and thick sheet (163 g sheet). When the angles α and β are reduced, a conveying resistance at a leading edge of the sheet P to be fed increases to cause defective sheet feeding. In addition, when the angles α and β are increased, this results in reduced leading-edge separating action for the sheets P to cause double feeding.
- In this way, when it is assumed that an angle formed by the tangent B of the
sheet feeding roller 4 and thesheet feeding rollers 23 in the pushing portion N1 and thesheet guide surface 26 is a, and an angle formed by the tangent in the abutting portion N2, where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, and thesheet guide surface 26 is β, by setting the angles α and β as 110°≦α≦135° and 170°≦β≦175°, occurrence of defective sheet feeding and double feeding is eliminated, and satisfactory sheet feeding performance is obtained with thin sheet and thick sheet.TABLE 1 (α/β) 110°˜135°/ 110°˜135°/ 110°˜135°/ 140°/ (Sheet type) 105°/165° 1650 170°˜175° 180° 170°˜175° 60 g sheet defective Good Good Good Good Good sheet feeding double Good Good Good Improper Improper feeding Sheet Sheet Feeding Feeding 163 g sheet defective Improper Improper Good Good Good sheet Sheet Sheet feeding Feeding Feeding double Good Good Good Good Good feeding - In addition, when it is assumed that a coefficient of friction between the
sheet guide surface 26 and the sheet P is μ1, a coefficient of friction between theseparation pad 6 and the sheet P is μ2, and a coefficient of friction between thesheet feeding roller 4 and the sheet P is μ3, the coefficients of friction are set so as to satisfy a relation of μ1<μ2<μ3. In this embodiment, the coefficient of friction μ1 between thesheet guide surface 26 and the sheet P is set to about 0.1 to 0.2, the coefficient of friction μ2 between theseparation pad 6 and the sheet P is set to about 0.7 to 1.0, and the coefficient of friction μ3 between thesheet feeding roller 4 and the sheet P is set to about 1.5 to 2.0. - In this way, when it is assumed that a coefficient of friction between the
sheet guide surface 26 and the sheet P is μ1, a coefficient of friction between theseparation pad 6 and the sheet P is μ2, and a coefficient of friction between thesheet feeding roller 4 and the sheet P is μ3, by setting the coefficients of friction so as to satisfy a relation of μ1<μ2<μ3, there is an effect in that a conveying resistance of the sheet P on thesheet guide surface 26 is reduced to prevent defective sheet feeding. There is also an effect in that separating performance in the abutting portion N2, where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, is improved to prevent double feeding. - (Sheet Feeding Operation)
- A sheet feeding operation of the sheet feeding apparatus of the present invention will be explained.
FIG. 6 is a partial sectional view of the sheet feeding apparatus in a sheet feeding operation.FIG. 7 is a partial sectional view of the sheet feeding apparatus in a conveying operation. - The
sheet feeding roller 4 receives transmission of a drive force from a drive source such as a motor (not shown in the figure) and rotates in a direction of arrow D inFIG. 6 . Then, of the sheets P pushed against thesheet feeding roller 4 by thepressure plate 5 due to the force of thepressure spring 24, a few sheets P at the top including the one brought into abutment against thesheet feeding roller 4 are conveyed by thesheet feeding roller 4. Next, a leading edge P4 of the sheets P conveyed by thesheet feeding roller 4 are handled on thesheet guide surface 26, which is formed as an inclined surface inclined toward the abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, whereby the sheets P are subjected to a separating action and separated (hereinafter referred to as first separation). Subsequently, the sheets P, which could not be separated on thesheet guide surface 26, are separated in the abutting portion N2 where therubber material 6 a of theseparation pad 6 and thesheet feeding roller 4 come into abutment against each other, (hereinafter referred to as second separation) to send only one sheet, which is in abutment against thesheet feeding roller 4, to thesheet conveying path 8 so as to be fed to the first conveyingroller pair 7. - As shown in
FIG. 7 , when thesheet feeding roller 4 makes one revolution and stops at a standby position, the sheet P conveyed by the first conveyingroller pair 7 is conveyed while being brought into abutment against thesheet feeding sub-rollers 23 by a pushing force of thepressure plate 5 and theseparation pad 6. Then, after passing over thepressure plate 5, a trailing edge P5 of the sheet P is led to the abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, while being guided by thesheet guide surface 26. - In the sheet feeding apparatus according to the first embodiment of the present invention, after passing over the
pressure plate 5, the trailing edge P5 of the sheet P is led to the abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, while being guided by thesheet guide surface 26. Thus, there is an effect in that generation of trailing edge jumping sound can be reduced. - In addition, the sheets P are subjected to separating actions in two stages consisting of the first separation for handling and separating the sheets P on the
sheet guide surface 26 formed as an inclined surface and the second separation for separating the sheets P in the abutting portion N2 where therubber material 6 a of theseparation pad 6 and thesheet feeding roller 4 come into abutment against each other. Thus, there is an effect in that the double feeding preventing effect is improved. - In addition, by setting an angle of the
sheet guide surface 26 and an angle of theseparation pad 6 to the above-mentioned angles, a sheet is delivered from thesheet feeding cassette 3 substantially in a vertical direction. Thus, the sheets, which are housed horizontally, are rapidly oriented upward and fed in the separating portion of thesheet feeding roller 4 and theseparation pad 6 and passed to thesheet conveying path 8 arranged in a vertical direction. In this way, since the horizontally supported sheets can be delivered in the vertical direction, a size in the horizontal direction of the sheet feeding apparatus can be suppressed to realize a reduction in the size of the printer 1. - Second Embodiment
- Next, a second embodiment of the sheet feeding apparatus in accordance with the present invention will be explained with reference to
FIGS. 8 and 9 . Note that only structures and operations different from those in the first embodiment will be explained. The other structures and operations are the same as those in the first embodiment. -
FIG. 8 is a sectional view of asheet feeding apparatus 2 in accordance with the second embodiment.FIG. 9 is a perspective view of asheet feeding cassette 3 that is mounted on this sheet feeding apparatus. - In the
sheet feeding apparatus 2, theinclined guide surface 26, which is provided between the pushing portion N1 where the sheets P are pushed against thesheet feeding roller 4 by thepressure plate 5 and the abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, and which guides the sheets P delivered by thesheet feeding roller 4 toward the abutting portion N2, is formed integrally with theholder 6 b of theseparation pad 6. - In this structure, the sheets P are subjected to separating actions in two stages consisting of the first separation for handling and separating the sheets P on the
sheet guide surface 26 formed in a slope shape and the second separation for separating the sheets P in the abutting portion N2 where therubber material 6 a of theseparation pad 6 and thesheet feeding roller 4 come into abutment against each other. Thus, there is an effect in that improved double-sheet feeding preventing effect can be attained. - In addition, after passing over the
pressure plate 5, the trailing edge P5 of the sheet P is led to the abutting portion N2, where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, while being guided by thesheet guide surface 26. Thus, there is an effect in that generation of trailing edge jumping sound can be reduced. - Third Embodiment
- Next, a third embodiment of the sheet feeding apparatus in accordance with the present invention will be explained.
FIG. 10 is a main part sectional view of the sheet feeding apparatus in accordance with the third embodiment. Only structures and operations different from those of the first and the second embodiments will be described. The other structures and operations are the same as those in the first and the second embodiments. - In the
sheet feeding apparatus 2, thesheet guide surface 26 is formed in an arc shape with an inner diameter surface thereof serving as a sheet guide. Thesheet guide surface 26 is provided between the pushing portion N1, where the sheets P are pushed against thesheet feeding roller 4 by thepressure plate 5, and the abutting portion N2, where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, and guides the sheets P delivered by thesheet feeding roller 4 toward the abutting portion N2. - In this structure, a separating action acts on the sheets P, which are conveyed by the
sheet feeding roller 4, at a curvature on thesheet guide surface 26 formed in an arc shape toward the abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, and the sheets P are subjected to the first separation. - Subsequently, the sheets P, which could not be separated on the
sheet guide 26 are subjected to the second separation in the abutting portion N2, where therubber material 6 a of theseparation pad 6 and thesheet feeding roller 4 come into abutment against each other, to send only one sheet, which is in abutment against thesheet feeding roller 4, to thesheet conveying path 8 so as to be fed to the first conveyingroller pair 7. - Thus, the sheets P are subjected to separating actions in two stages consisting of the first separation for separating the sheets P at a curvature on the
sheet guide surface 26 formed in an arc shape and the second separation for separating the sheets P in the abutting portion N2 where therubber material 6 a of theseparation pad 6 and thesheet feeding roller 4 come into abutment against each other. Thus, there is an effect in that the double feeding preventing effect is improved. - In addition, after passing over the
pressure plate 5, the trailing edge P5 of the sheet P is led to the abutting portion N2 where thesheet feeding roller 4 and theseparation pad 6 come into abutment against each other, while being guided by thesheet guide surface 26, similarly to the first embodiment. Thus, there is an effect in that generation of trailing edge jumping sound can be reduced. - Fourth Embodiment
- Next, a fourth embodiment of the sheet feeding apparatus in accordance with the present invention will be explained.
FIG. 11 is a sectional view of the sheet feeding apparatus in accordance with the fourth embodiment.FIG. 12 is a perspective view of a sheet feeding cassette to be mounted on the sheet feeding apparatus. Only structures and operations different from those in the first to the third embodiments will be explained. The other structures and operations are the same as those in the first to the third embodiments. - The
sheet guide surface 26 is constituted by a tabular member of metal, fixed to thesheet feeding cassette 3 by fixing means such as screws or fitting, and grounded. Since thesheet guide surface 26 is constituted by the tabular member of metal and grounded in this way, there is an effect in that wear of thesheet guide surface 26 due to conveyance and sliding of the sheet P is prevented and occurrence of defective sheet feeding and double feeding due to the wear of thesheet guide surface 26 is prevented. In addition, since charging due to sliding of the sheet P and thesheet guide surface 26 can be prevented, there is an effect in that a defective image due to charging is prevented.
Claims (13)
1. A sheet feeding apparatus comprising:
sheet containing means for containing sheets;
a sheet feeding roller for feeding the sheets contained in said sheet containing means;
pushing means for pushing the sheets contained in said sheet containing means against said sheet feeding roller;
a separation pad which is provided at a position to be capable of abutting against the sheet feeding roller and separates the sheets one by one as the sheets are fed by the sheet feeding roller and said pushing means; and
a sheet guide portion arranged between a pushing portion where the sheets are pushed against the sheet feeding roller by said pushing means and an abutting portion where the sheet feeding roller and the separation pad come into abutment against each other.
2. A sheet feeding apparatus according to claim 1 ,
wherein the sheet guide portion is formed integrally with said sheet containing means.
3. A sheet feeding apparatus according to claim 1 ,
wherein the sheet guide portion has as inclined surface that is inclined from the pushing portion where the sheets are pushed against the sheet feeding roller by said pushing means, toward the abutting portion where the sheet feeding roller and the separation pad come into abutment against each other.
4. A sheet feeding apparatus according to claim 1 ,
wherein the sheet guide portion has an arc shape with an inner diameter surface thereof serving as a sheet guide.
5. A sheet feeding apparatus according to claim 1 , wherein said pushing means rotates about its rotation center to push the sheets against the sheet feeding roller and is arranged with respect to the sheet feeding roller such that a tangent direction of the pushing portion, where the sheets are pushed against the sheet feeding roller by said pushing means, and a direction of a surface on which the sheets pushed against the sheet feeding roller by said pushing means are stacked, coincide with each other.
6. A sheet feeding apparatus according to claim 1 ,
wherein, when it is assumed that an angle formed by a tangent of the pushing portion, where the sheets are pushed against the sheet feeding roller by said pushing means, and a guide surface of the sheet guide portion is α, and an angle formed by the guide surface of the sheet guide portion and a nip line of the abutting portion, where the sheet feeding roller and the separation pad come into abutment against each other, is β, the angles α and β respectively satisfy a relation of 110°≦α≦135° and a relation of 170°≦β≦175°
7. A sheet feeding apparatus according to claim 6 ,
wherein the separation pad includes a separating member formed of a rubber material and coming into abutment against the sheet feeding roller to separate the sheets, and a retaining member that retains the separating member, and wherein the sheet guide portion is formed integrally on an upstream side in a sheet conveying direction of the retaining member.
8. A sheet feeding apparatus according to claim 1 ,
wherein, when it is assumed that a coefficient of friction between a guide surface of the sheet guide portion and the sheets is μ1, a coefficient of friction between the separation pad and the sheets is μ2, and a coefficient of friction between the sheet feeding roller and the sheets is μ3, the coefficients of friction satisfies a relation of μ1<μ2<μ3.
9. A sheet feeding apparatus according to claim 1 ,
wherein a guide surface of the sheet guide surface is made of metal, and the sheet guide portion is grounded.
10. A sheet feeding apparatus comprising:
a sheet feeding cassette;
a sheet feeding roller which comes into abutment against sheets stacked on an intermediate plate provided in a cassette main body of the sheet feeding cassette and rotates to feed the sheets;
a separation pad which is provided at a position to be capable of abutting against the sheet feeding roller and separates the sheets one by one as the sheets are delivered by said sheet feeding roller; and
a sheet guide portion which is located between a pushing portion, where the sheets are pushed against the sheet feeding roller, and an abutting portion where said sheet feeding roller and the separation pad come into abutment against each other, and is formed integrally with the cassette main body.
11. A sheet feeding apparatus according to claim 9 ,
wherein, when it is assumed that an angle formed by a tangent of the pushing portion, where the sheets are pushed against the sheet feeding roller by said pushing means, and a guide surface of the sheet guide portion is α, and an angle formed by the guide surface of the sheet guide portion and a nip line of the abutting portion, where the sheet feeding roller and the separation pad come into abutment against each other, is β, the angles α and β respectively satisfy a relation of 110°≦α≦135° and a relation of 170°≦β≦175°
12. A sheet feeding apparatus according to claim 9 ,
wherein, when it is assumed that a coefficient of friction between a guide surface of the sheet guide portion and the sheets is μ1, a coefficient of friction between the separation pad and the sheets is μ2, and a coefficient of friction between the sheet feeding roller and the sheets is μ3, the coefficients of friction satisfies a relation of μ1<μ2<μ3.
13. An image forming apparatus comprising:
the sheet feeding apparatus according to any one of claims 1 to 12 ; and
an image forming portion that forms an image on the sheets delivered from the sheet feeding apparatus.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2003-190395 | 2003-07-02 | ||
JP2003190395A JP4006366B2 (en) | 2003-07-02 | 2003-07-02 | Sheet feeding apparatus and image forming apparatus |
Publications (1)
Publication Number | Publication Date |
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US20050001372A1 true US20050001372A1 (en) | 2005-01-06 |
Family
ID=33549811
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Application Number | Title | Priority Date | Filing Date |
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US10/878,467 Abandoned US20050001372A1 (en) | 2003-07-02 | 2004-06-29 | Sheet feeding apparatus and image forming apparatus |
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US (1) | US20050001372A1 (en) |
JP (1) | JP4006366B2 (en) |
KR (1) | KR100558823B1 (en) |
CN (1) | CN100337838C (en) |
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US20080093792A1 (en) * | 2006-10-20 | 2008-04-24 | Samsung Electronics Co., Ltd | Sheet feeding unit and image forming apparatus having the same |
US20080179816A1 (en) * | 2007-01-31 | 2008-07-31 | Neopost Technologies | Separator for separating envelopes from a stack |
US20090281152A1 (en) * | 2006-07-14 | 2009-11-12 | Gerard Martin Paul Giblin | Indole Compounds Having Affinity to the EP1 Receptor |
US20110156340A1 (en) * | 2009-12-28 | 2011-06-30 | Brother Kogyo Kabushiki Kaisha | Sheet feed device |
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JP5549240B2 (en) * | 2010-01-25 | 2014-07-16 | セイコーエプソン株式会社 | Sheet material feeding apparatus and recording apparatus |
CN102674038A (en) * | 2012-04-23 | 2012-09-19 | 济南立昱机械科技有限公司 | Automatic bag feeding machine for valve bags |
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Cited By (9)
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US20080001352A1 (en) * | 2006-06-30 | 2008-01-03 | Nautilus Hyosung Inc. | Atm equipped with structure for preventing rotation of stack roller |
US20090281152A1 (en) * | 2006-07-14 | 2009-11-12 | Gerard Martin Paul Giblin | Indole Compounds Having Affinity to the EP1 Receptor |
US20080093792A1 (en) * | 2006-10-20 | 2008-04-24 | Samsung Electronics Co., Ltd | Sheet feeding unit and image forming apparatus having the same |
US7673872B2 (en) * | 2006-10-20 | 2010-03-09 | Samsung Electronics Co. Ltd | Sheet feeding unit and image forming apparatus having the same |
US20080179816A1 (en) * | 2007-01-31 | 2008-07-31 | Neopost Technologies | Separator for separating envelopes from a stack |
US20110198799A1 (en) * | 2007-01-31 | 2011-08-18 | Neopost Technologies | Separator for separating envelopes from a stack |
US20110156340A1 (en) * | 2009-12-28 | 2011-06-30 | Brother Kogyo Kabushiki Kaisha | Sheet feed device |
EP2338815A3 (en) * | 2009-12-28 | 2012-09-19 | Brother Kogyo Kabushiki Kaisha | Sheet feed device |
US8403322B2 (en) | 2009-12-28 | 2013-03-26 | Brother Kogyo Kabushiki Kaisha | Sheet feed device |
Also Published As
Publication number | Publication date |
---|---|
JP2005022818A (en) | 2005-01-27 |
KR100558823B1 (en) | 2006-03-10 |
CN100337838C (en) | 2007-09-19 |
CN1576041A (en) | 2005-02-09 |
JP4006366B2 (en) | 2007-11-14 |
KR20050004055A (en) | 2005-01-12 |
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Legal Events
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AS | Assignment |
Owner name: CANON KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YUZA, AKIRA;MATSUO, YOSHIHIRO;REEL/FRAME:015532/0723;SIGNING DATES FROM 20040621 TO 20040622 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |