EP0433952B1 - Appareil d'alimentation en feuilles - Google Patents

Appareil d'alimentation en feuilles Download PDF

Info

Publication number
EP0433952B1
EP0433952B1 EP19900124469 EP90124469A EP0433952B1 EP 0433952 B1 EP0433952 B1 EP 0433952B1 EP 19900124469 EP19900124469 EP 19900124469 EP 90124469 A EP90124469 A EP 90124469A EP 0433952 B1 EP0433952 B1 EP 0433952B1
Authority
EP
European Patent Office
Prior art keywords
sheet
sheets
conveying means
feeding apparatus
sheet feeding
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.)
Expired - Lifetime
Application number
EP19900124469
Other languages
German (de)
English (en)
Other versions
EP0433952A2 (fr
EP0433952A3 (en
Inventor
Hisao C/O Canon K. K. Nakajima
Yasumi C/O Canon K. K. Yoshida
Minoru C/O Canon K. K. Nada
Noriaki C/O Canon K. K. Koyanagi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from JP1327819A external-priority patent/JPH03186577A/ja
Priority claimed from JP1343865A external-priority patent/JP2825891B2/ja
Priority claimed from JP2016585A external-priority patent/JP2648521B2/ja
Priority claimed from JP2027761A external-priority patent/JP2648523B2/ja
Application filed by Canon Inc filed Critical Canon Inc
Publication of EP0433952A2 publication Critical patent/EP0433952A2/fr
Publication of EP0433952A3 publication Critical patent/EP0433952A3/en
Application granted granted Critical
Publication of EP0433952B1 publication Critical patent/EP0433952B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • G03G15/6579—Refeeding path for composite copying
    • 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
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/23—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 specially adapted for copying both sides of an original or for copying on both sides of a recording or image-receiving material
    • G03G15/231—Arrangements for copying on both sides of a recording or image-receiving material
    • G03G15/232—Arrangements for copying on both sides of a recording or image-receiving material using a single reusable electrographic recording member
    • G03G15/234—Arrangements for copying on both sides of a recording or image-receiving material using a single reusable electrographic recording member by inverting and refeeding the image receiving material with an image on one face to the recording member to transfer a second image on its second face, e.g. by using a duplex tray; Details of duplex trays or inverters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00367—The feeding path segment where particular handling of the copy medium occurs, segments being adjacent and non-overlapping. Each segment is identified by the most downstream point in the segment, so that for instance the segment labelled "Fixing device" is referring to the path between the "Transfer device" and the "Fixing device"
    • G03G2215/00417—Post-fixing device
    • G03G2215/0043—Refeeding path
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00367—The feeding path segment where particular handling of the copy medium occurs, segments being adjacent and non-overlapping. Each segment is identified by the most downstream point in the segment, so that for instance the segment labelled "Fixing device" is referring to the path between the "Transfer device" and the "Fixing device"
    • G03G2215/00417—Post-fixing device
    • G03G2215/0043—Refeeding path
    • G03G2215/00434—Refeeding tray or cassette
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00535—Stable handling of copy medium
    • G03G2215/00556—Control of copy medium feeding
    • G03G2215/00578—Composite print mode
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00535—Stable handling of copy medium
    • G03G2215/00556—Control of copy medium feeding
    • G03G2215/00586—Control of copy medium feeding duplex mode

Definitions

  • the present invention relates to a sheet feeding apparatus according to the preamble of claim 1.
  • Such an apparatus may be used in an image forming system having a sheet re-feeding mechanism for re-feeding a sheet from an intermediate tray and being capable of performing a both-surface printing operation and a multi-print operation.
  • the invention further relates to an image forming system including said apparatus and a sheet feeding method.
  • a both-surface image forming system generally includes an intermediate tray for receiving and stacking sheets each having an image printed on its one surface. After the image forming operation regarding first surfaces of the sheets has been completed, the sheets stacked in the intermediate tray are separated and fed one by one to introduce the sheet again into an image forming portion, where an image is printed on a second surface of the sheet.
  • An important matter in performing such both-surface image forming operation is the reliability of the sheet feeding whether the sheet can be fed properly or not. Particularly, the reliability of the sheet re-feeding operation whether the sheet having the image printed on its first surface can be accurately separated and fed one by one from the intermediate tray is a problem.
  • Fig. 11 shows an example of a conventional both-surface image forming system comprising a sheet feeding apparatus according to the precharacterizing part of claim 1 and disclosed in the document EP-A-0 303 276.
  • the image forming system includes a body or frame 1, an original support 2 on which an original is rested, a photosensitive drum 3 which can bear an image from the original, mirrors 4, 5, 6, 7 for directing the image on the original to the photosensitive drum 3, a focusing lens 8 for focusing the image on the photosensitive drum, and a transfer electrode 9 for transferring a toner image formed on the photosensitive drum onto a sheet P.
  • the sheet P stored in a cassette 10 is picked up by a supply roller 11 and is fed out by regist rollers 12 at a predetermined timing synchronous with the image formed on the photosensitive drum 3. After the toner image has been transferred onto the sheet by the transfer electrode 9, the toner image is fixed to the sheet by means of a fixing device 13. When an image is superimposed on the first surface of the same sheet P, the sheet P is directed to a sheet feeding path 15 by a switching guide 14 and is then stored in an intermediate tray 16.
  • the sheet P is directed to a sheet feeding path 17 by the switching guide 14 and is ejected halfway by means of ejector rollers 18. Then, by reversing the ejector rollers 18, a trailing end of the sheet P is introduced into a sheet feeding path 20 by means of a switching guide 19 and then is stored in the intermediate tray 16.
  • the sheet P having the image formed on its first surface is re-fed from the intermediate tray 16 one by one and is sent to the image forming portion, where the image is printed on the second surface of the sheet.
  • the sheets P stacked in the intermediate tray 16 may include the silicone oil adhered on its imaged surface (first surface) or may have a curled end portion formed due to heat and pressure in the fixing device.
  • Fig. 12 shows an example of a both-surface image forming system designed to enhance such reliability.
  • this conventional image forming system whenever the sheet is introduced into the intermediate tray 16, the whole sheet stack is shifted slightly by means of a pair of conveying rollers 21, so that the sheets are stacked in a stepped fashion.
  • the sheet stack overlapped in such stepped fashion is wholly conveyed toward a pair of rollers 22 after the image forming operation regarding first surfaces of the sheets has been completed. Then, by stopping the activation of the paired conveying rollers 21 immediately after a lowermost sheet P in the sheet stack leaves the paired conveying rollers 21, only the lowermost sheet P pinched between the paired rollers 22 is fed out by such rollers 22 for the second surface printing operation. According to this example, it is possible to improve the prevention of the double-feed of the sheets during the sheet re-feeding operation.
  • the optimum positional relation between the paired rollers 21 and 22 as shown in Fig. 13A must be satisfied regarding the smallest size sheet P and at the same time a condition as shown in Fig. 13B must be satisfied regarding the larger size sheets. That is to say, only the lowermost sheet to be re-fed is separated from the paired rollers 21 and the remaining sheets are pinched by the paired rollers 21, and at least the lowermost sheet is pinched by the paired rollers 22.
  • a rubber driving roller 22b of the paired rollers 22 shifts the lowermost sheet. The remaining sheets are not shifted since they are pinched by the paired rollers 21.
  • the lowermost sheet P 1 is shifted toward a direction shown by the arrow while slidingly contacting with a second or upper sheet P 2 .
  • the toner particles on the second sheet P 2 in the nip area are transferred onto a hatched area of the lowermost sheet P 1 and thus are peeled from the second sheet P 2 .
  • the toner particles on the lowermost sheet are transferred onto the second sheet P 2 at the nip area, and thus, the toner particles on the hatched area of the lowermost sheet P 1 are peeled from the lowermost sheet.
  • an object of the present invention is to provide a sheet feeding apparatus an image forming system including the same and a sheet feeding method which can positively re-feed sheets without smearing the latter by providing a sheet re-feeding means for re-feeding the sheets without frictionally sliding the sheets with respect to each other, regardless of the different sizes of the sheets in a sheet stack formed in a stepped fashion.
  • Fig. 1 shows an image forming system incorporating the present invention, which is embodied as a copying machine which can perform the both-surface printing operation and the multi-print operation.
  • a sensor 24 for detecting a leading end of a sheet P is arranged at a downstream side of the sheet feeding path 23 and a pair of conveying rollers 25 are disposed near and at an upstream side of the sensor 24. Further, an upper guide 26 of the sheet feeding path 23 extends rearwardly and downwardly and a lower horizontal guide 27 is arranged below the guide 26 in confronting relation thereto.
  • a driving rubber roller 28a is disposed in such a manner that a nip of this driving roller is substantially flush with the lower guide 27.
  • a driven roller 28b made of resin material having lower frictional coefficiency than that of rubber material is arranged above the driving roller 28a for up-and-down movement and is biased to urge against the driving roller by means of a leaf spring 29.
  • Upper and lower guides 30 and 31 similar to the upper and lower guides 26, 27 are disposed at the right of the driving and driven rollers 28a, 28b, and a pair of rollers 32a, 32b are arranged at the right of the guide 30, 31 in such a manner that a nip between these rollers 32a, 32b is substantially flush with an upper surface of the lower guide 31.
  • the roller 32a is rotatably supported on a fixed shaft (not shown).
  • the roller 32b is mounted for up-and-down movement and is biased downwardly to urge against the roller 32a by means of a leaf spring 34.
  • upper and lower guides 35 and 36 are curved upwardly from horizontal positions and are disposed in such a manner that the nip between the rollers 32a, 32b is substantially flush with an upper surface of the lower guide 36.
  • a branch guide 37 is branched rearwardly and upwardly from this upper guide 30 near the paired rollers 32a, 32b, and a separating claw 38 is rotatably supported on a shaft 38a at a base end of the branch guide 37.
  • a free pointed end of the separating claw 38 has a thickness t smaller than a thickness of the sheet P being conveyed, and is abutted against a step or shoulder formed between the first sheet P 1 and the second sheet P 2 when the sheet stack is shifted rightwardly, whereby, as shown in Fig. 3B, the first sheet P 1 is permitted to be shifted rightwardly, but the second sheet P 2 is separated upwardly from the first sheet.
  • a sensor 39 for detecting the sheet P is attached to the lower guide 31.
  • a driving roller of the paired rollers 25, roller 28a and roller 32a are connected to respective stepping motors 25m, 28m and 32m through corresponding gear trains (not shown), respectively, and signalling circuits of the stepping motors 25m, 28m, 32m, are connected to a controlling portion 33 so that these stepping motors can be rotated normally or reversely by predetermined angles.
  • the separating claw 38 is connected to a solenoid 38s, and a signalling circuit for the solenoid is connected to the controlling portion 33.
  • rollers 28a, 32a are made of rubber material having high coefficient of friction
  • rollers 28b, 32b are made of resin material and the like having low coefficient of friction (good slidability).
  • the reference numeral 40 denotes a keyboard for inputting the command regarding the number of copies, both-surface printing mode, multi-print mode, copy start or the like; and 41 denotes a size detection device. Signalling circuits of these elements 40, 41 are connected to the controlling portion 33.
  • step S2 When the both-surface printing mode or the multi-print mode is selected and the copy start is commanded through the keyboard 40, the sheet P which was picked up from the cassette 10 and on (a first surface of) which the image was formed as mentioned above is sent to the roller 25 starting its rotation in a step S1. From when a leading end of the sheet P is detected by the sensor 24 (step S2), after a predetermined time period t 1 required for bringing the leading end of the sheet to the nip between the rollers 28a, 28b to form a loop in the sheet and to correct the skew-feed of the sheet has been elapsed (step S3), the motor 28m is turned ON (step S4).
  • the motor 28m is rotated for a predetermined time period t 2 required for conveying the sheet by a pre-selected distance l 0 from a condition that the sheet is pinched by the paired rollers 28a, 28b (Fig. 5).
  • the motor 28m is reversed (step S6).
  • the reverse rotation of the motor 28m is stopped (step S8) after a predetermined time period (t 2 - ⁇ t) shorter than the time period t 2 has been elapsed (step S7).
  • the sheet P is conveyed in the reverse direction by means of the paired rollers 28a, 28b so that the leading end of the sheet P is positioned at a predetermined distance l from the nip between the paired rollers 28a, 28b in a downstream direction (Fig. 6).
  • the trailing end of the sheet reaches below the paired rollers 25 while being guided on the lower guide 27.
  • the rotation of the paired rollers 28a, 28b may be controlled by the number of pulses sent from the controlling portion 33 to the motor 28m. That is to say, after the leading end of the sheet reaches the nip between the paired rollers 28a, 28b, by sending the number of pulses corresponding to the rotation angle required to convey the sheet P by the predetermined distance, the paired rollers 28a, 28b can be controlled.
  • a step S9 it is judged whether a set number of sheets have been stacked or not. If not, the sequence returns to the step S2 and a next sheet is conveyed.
  • these rollers are operated in the same manner as mentioned above, while pinching the first sheet P, with the result that a leading end of the next or second sheet P is positioned at the distance l from the nip between the rollers 28a, 28b in the downstream direction.
  • the first sheet P is conveyed together with the second sheet P and the leading end of the first sheet is positioned at the distance l from the leading end of the second sheet in the downstream direction.
  • the motors 28m and 32m start to be rotated (steps S11, S12) and the stacked sheets P are sent to the paired rollers 32a, 32b.
  • the separating claw 38 is activated (step S15) to move from a waiting position shown in Fig. 7 to an operating position shown in Fig. 9 so that the stacked sheets P other than the lowermost sheet P can be introduced into the branch guide 37.
  • a time period t 4 is so selected that, when the separating claw 38 moves to the position of Fig. 9, the free end of the claw abuts against a surface of the lowermost sheet at a upstream side of the leading end of the lowermost sheet P 1 and at a downstream side of the leading end of the next or second sheet P 2 .
  • step S17 the motor 28m is reversed (step S17) to shift the stacked sheets P other than the lowermost sheet P in a reverse direction and only the lowermost sheet P 1 is conveyed in the normal direction.
  • the motor 28m is stopped (step S19).
  • the motor 32m is stopped (step S21) when a time period t 6 required for bringing the lowermost sheet P 1 to a next pair of rollers is elapsed (step S20).
  • the time periods t 3 , t 4 , t 5 and t 6 are selected in accordance with the size of the sheet P, distances between the rollers and diameters of the rollers, and are stored in the controlling portion 33.
  • the controlling portion 33 judges these data together with information from the sheet size detection device 41 to command the motors 28m, 32m.
  • step S11 The sequence from the step S11 to the step S21 is repeated until the set or selected number of sheets are treated, and thereafter, the copying operation is finished (step S22).
  • the sheet may be fed out (re-fed) from the top of the stacked sheets (each having an image formed on its first surface) (i.e., an uppermost sheet), as a second embodiment shown in Fig. 10).
  • the sheet stack may be formed by overlapping a next sheet on a previous sheet shifted back to obtain a distance (- l ) (in place of the distance l in Fig. 6), and the branch guide 37 and the separating claw 38 may be arranged below the lower guide 31.
  • a pair of rollers 42 are arranged below the sheet feeding path 23.
  • the separating claw 38 may be constructed by attaching a thin elastic sheet 38c (polyester film having a thickness of 50 ⁇ m) to a holding member 38b (see Fig. 3D).
  • a thin elastic sheet 38c polyyester film having a thickness of 50 ⁇ m
  • a protruding amount of the sheet may be smaller than 5 mm.
  • the separating claw 38 may have a semi-circular free end. By adopting such configuration, the leading end of the sheet P can be prevented from being stopped by the free end 38d of the separating claw 38.
  • the returning of the separating claw 38 in the step S19 may be effected between the steps S16 and S17.
  • Figs. 16 and 17 show an image forming system incorporating the third embodiment of the present invention, which is embodied as a copying machine which can perform the both-surface printing operation and the multi-print operation with different colors.
  • a separating claw 50 having a free end directed toward a downstream side is arranged in the vicinity of a rear end of the lower guide 31 near the roller 28b, which separating claw protrudes slightly above the lower guide 31.
  • the separating claw can separate the lowermost sheet P 1 fed back in the reverse direction from other sheets.
  • the rear end of the separating claw 50 has a bent portion 31a bent downwardly to introduce the separated lowermost sheet P 1 between the separating claw and the lower guide.
  • a sequence for stacking a plurality of sheets on the lower guide (re-feeding path) is the same as that in the first embodiment described with reference to the flow chart of Fig. 4.
  • FIG. 18 shows a condition at a point that the step S5 in Fig. 4 is finished
  • Fig. 19 shows a condition at a point that the motor 28m is stopped in the step S8
  • Fig. 20 shows a condition that the sheets are stacked by repeating the sequences of the steps S1 to S9 in the flow chart of Fig. 4.
  • step S111 When the start is commanded through the keyboard 40 (step S111), the motors 28m and 32m start to be rotated (steps S112, S113) and the stacked sheets P are sent to the paired rollers 32a, 32b.
  • step S112, S113 the motors 28m and 32m start to be rotated
  • the stacked sheets P are sent to the paired rollers 32a, 32b.
  • the motor 28m is reversed (steps S114, S115, S116, S117). This condition is shown in Fig. 22. After a time period t 14 has been elapsed from the initiation of the reverse movement of the stacked sheets, only the lowermost sheet P 1 is pinched by the paired rollers 32a, 32b.
  • the lowermost sheet P 1 is separated from the other sheets by the separating claw 50 and is guided between the separating claw 50 and the bent portion 31a, with the result that the lowermost sheet is not pinched by the paired rollers 28a, 28b.
  • the motor 28m is stopped and the motor 32m is normally rotated (steps S118, S119, S120). This condition is shown in Fig. 23.
  • step S121, S122 the motor 32m is stopped.
  • step S116, S117 the lowermost sheet P 1 is introduced between the separating claw 50 and the bent portion 31a and other stacked sheets including the second sheet P 2 are shifted back on the lower guide 27.
  • step S119, S120 the reverse movement of the stacked sheets is stopped, and at the same time the lowermost sheet P 1 is fed out by means of the paired rollers 32a, 32b.
  • the sequence returns to the step S112, and the same sequence is repeated.
  • the set number of sheets are re-fed (step S123)
  • the sequence is ended. During the conveyance of the lowermost sheet P 1 , since the other stacked sheets are pinched by the paired rollers 28a, 28b, these remaining sheets are not fed together with the lowermost sheet.
  • the sheets having different sizes be stacked in the stepped fashion and be separated and re-fed one by one, without changing the distance between the paired rollers 28a, 28b and 32a, 32b. That is to say, in the case where the sheets P are stacked in the stepped fashion, the time periods t 2 and (t 2 - ⁇ t) in the flow chart of Fig. 4 may be changed in accordance with the length of the sheet in a feeding direction. In order to draw out the trailing end of the sheet from the paired rollers 25, the time period t 2 may be prolonged as the longer sheet is treated. Similarly, by setting the time period (t 2 - ⁇ t) in accordance with the length of the sheet, the sheets having different sizes can be stacked in the stepped fashion with offsetting by the distance l , respectively.
  • the time periods t 13 , t 14 and t 15 in the flow chart of Fig. 21 may be changed in accordance with the length of the sheet P. Since the time period t 3 corresponds to a time required for drawing out the trailing end of the lowermost sheet P 1 from the free end of the separating claw 50, this time period is set to be prolonged as the longer sheet is treated. Similarly, since the time period t 4 corresponds to a time required for drawing out the stacked sheets not to be re-fed from the paired rollers 32a, 32b, this time period is also set to be prolonged as the longer sheet is treated.
  • the size of the sheet P is detected by the sheet size detection device 41 of Fig.
  • the sheet size detection device 41 may be of any conventional type wherein the size of the sheet is detected from the cassette or wherein the size of the sheet is detected on the basis of the time passing through the sensor.
  • a separating claw 51 is rotatably mounted on a shaft 51a and is weakly biased in an anti-clockwise direction (to urge a free end of the claw against the stacked sheets) by means of a tension spring 61. Further, a stopper 62 is provided for preventing the separating claw 51 from lowering below a position where the separating claw protrudes slightly above the lower guide 31.
  • a solenoid 63 is provided for positioning the separating claw 61, and the stopper 62 is omitted.
  • the offset distance l as shown in Fig. 19 is reversed to (- l ).
  • a next sheet P is stacked or overlapped on the previous sheet or sheets with offsetting the leading end of the next sheet by the distance l in the sheet re-feeding direction.
  • an uppermost sheet, i.e., lastly stacked sheet P 1 will be firstly re-fed.
  • a pair of rollers 44 are provided in connection with the lower guide 27. Furthermore, since the first sheet (firstly re-fed sheet) P 1 is rested on the sheet stack, a bent portion 30a is formed on the upper guide 30 and cooperates with a separating claw 52 to form a sheet retarding path 30b.
  • Fig. 28 shows an image forming system incorporating the seventh embodiment of the present invention, which is embodied as a copying machine which can perform the both-surface printing operation and the multi-print operation with different colors.
  • An L-shaped stopper 53 is rotatably mounted on a shaft 53a in the vicinity of a rear end of the lower guide 31 near the paired rollers 28a, 28b to be extended or retracted through an opening formed in the lower guide 31.
  • a switching guide plate 64 which can form a part of the lower guide 31 when closed and can be opened toward a lower retarding space 65.
  • a sequence for stacking a plurality of sheets on the lower guide (re-feeding path) 27 is the same as that in the first embodiment described with reference to the flow chart of Fig. 4.
  • FIG. 30 shows a condition at a point that the step S5 in Fig. 4 is finished
  • Fig. 31 shows a condition at a point that the motor 28m is stopped in the step S8
  • Fig. 20 shows a condition that the sheets are stacked by repeating the sequences of the steps S2 to S9 in the flow chart of Fig. 4.
  • step S211 When the start is commanded through the keyboard 40 (step S211), the motors 28m and 32m start to be rotated (steps S212, S213) and the stacked sheets P are sent to the paired rollers 32a, 32b.
  • a solenoid 53s for driving the stopper 53 and a solenoid 64s for driving the switching guide plate are turned ON (step S216), so that the stopper 53 is protruded above the switching guide plate 64 to stop the trailing end of the first sheet P and the switching guide plate 64 is opened.
  • the motors 28m, 32m are rotated reversely (steps S217, S218).
  • the timing for reversing these motors is set by a time period t 23 elapsed (step S215) after the leading end of the first sheet P is detected by the sensor 39 (step S214). At this point, the lowermost sheet P, and other sheets rested on the lowermost sheet and positioned between the paired rollers 32a, 32b are all pinched by the paired rollers 32a, 32b, as shown in Fig. 34.
  • a time period t 24 in the step S219 and a time period t 25 in the step S222 are set by the controlling portion 33 on the basis of the information from the sensor 39 and the size detection device 41.
  • step S224 the stopper 53 and the switching guide plate 64 are returned to their original positions. Further, if the set number of sheets are not yet re-fed, the sequence returns to the step S212 and the above-mentioned operation is repeated; whereas, when the set number of sheets are re-fed (step S225), the copying operation is ended.
  • Figs. 35 and 36 show an image forming system incorporating the eighth embodiment of the present invention, which is embodied as a copying machine which can perform the both-surface printing operation and the multi-print operation with different colors.
  • structural elements similar to those of the first embodiment shown in Fig. 1 are designated by the same reference numerals and the explanation thereof will be omitted.
  • a branch guide 37 extending rearwardly and upwardly is arranged on the upper guide 30 near the paired rollers 32a, 32b, and a flapper (separating claw) 38 is rotatably supported on a shaft 38a at a base end of the flapper 38.
  • the lower guide 31 has a recessed portion 70 in the vicinity of a lowered position of the flapper 38.
  • a bottom surface 38b of the flapper 38 is spaced apart by a distance H from a bottom surface of the recessed portion 70 and is positioned slightly below the surface of the lower guide 31 by a distance h 1 , when the flapper is lowered.
  • a sequence for stacking a plurality of sheets on the lower guides (re-feeding path) 27, 31 is the same as that in the first embodiment described with reference to the flow chart of Fig. 4.
  • FIG. 37 shows a condition at a point that the step S5 in Fig. 4 is finished
  • Fig. 38 shows a condition at a point that the motor 28m is stopped in the step S8
  • Fig. 39 shows a condition that the sheets are stacked by repeating the sequences of the steps S1 to S9 in the flow chart of Fig. 4.
  • a sequence for separating and re-feeding the stacked sheets one by one is the same as that in the first embodiment, and thus, is executed in accordance with the flow chart of Fig. 8.
  • This eighth embodiment differs from the first embodiment in the operation of the flapper 38 lowered by the action of the solenoid 38s in the step S15 of the flow chart in Fig. 8. That is to say, as shown in Fig. 40, when the flapper 38 is lowered, it urges the first or lowermost sheet P 1 down toward the recessed portion 70 and separates this lowermost sheet from the other sheets. Since the bottom surface of the flapper 38 is positioned below the lower guide 31 by the distance h 1 as shown in Fig. 36B, the second sheet P 2 and other sheets thereon ride on the flapper, thus being separated from the lowermost sheet. Incidentally, the lowermost sheet P 1 can advance in a clearance between the flapper 38 and the recessed portion 70 by the aid of its own resiliency.
  • step S16, S17 When a time period t 4 required for separating the trailing end of the first sheet P 1 from the paired rollers 28a, 28b as shown in Fig. 41 is elapsed, the motor 28m is reversed (steps S16, S17).
  • the first sheet P 1 is conveyed in the downstream direction by the paired rollers 32a, 32b, and the second sheet P 2 and other sheets thereon is shifted back by the paired rollers 28a, 28b to return to the original position, and then the motor 28m is stopped and the flapper 38 is returned to the position shown in Fig. 39 (steps S18, S19).
  • the uppermost sheet P may become the firstly fed sheet P 1 .
  • the paired rollers 28a, 28b cannot shift the trailing end of the sheet toward the left of these rollers, as shown in Fig. 42, another pair of rollers 242 are arranged at the left of the lower guide 27, thus shifting back the sheet by the distance (- l) from the paired rollers 28a, 28b.
  • a recessed portion 71 is formed in the upper guide 30, and the branch guide 37 and flapper 38 are disposed below the recessed portion 71.
  • the present invention provides a sheet feeding apparatus comprising first conveying means for conveying a sheet stack formed in a stepped fashion by offsetting each sheet by a predetermined distance in a predetermined direction toward the predetermined direction or toward an opposite direction, separating means disposed at a downstream side of the first conveying means in the predetermined direction and adapted to separate an outermost sheet from the sheet stack being fed by the first conveying means, second conveying means for conveying the sheet separated by the separating means, and control means for controlling the first conveying means in such a manner that the first conveying means is activated to convey the sheet stack in the predetermined direction and the first conveying means is stopped after the sheet separated by the separating means starts to be conveyed by the second conveying means.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Conveyance By Endless Belt Conveyors (AREA)
  • Sheets, Magazines, And Separation Thereof (AREA)
  • Counters In Electrophotography And Two-Sided Copying (AREA)

Claims (17)

  1. Appareil d'alimentation en feuilles comportant :
    des premiers moyens de transport (28a, 28b) destinés à transporter une pile de feuilles formée d'une manière étagée en décalant chaque feuille d'une distance prédéterminée (1) dans le sens d'avance des feuilles ;
    des seconds moyens de transport (32a, 32b) disposés sur un côté d'aval desdits premiers moyens de transport (28a, 28b) dans le sens d'avance des feuilles ; ledit appareil étant
       caractérisé par
    des moyens de séparation (37, 38 ; 50-53) disposés entre lesdits premiers et seconds moyens de transport (28a, 28b ; 32a, 32b) et conçus pour être positionnés entre la feuille la plus en avant (P1) et la partie restante des feuilles dans la pile de feuilles ; et
    des moyens de commande (33) destinés à commander lesdits premiers et seconds moyens de transport d'une manière telle que
    ladite pile de feuilles est transportée dans le sens d'avance des feuilles et dans le sens inverse, grâce à quoi ladite feuille située le plus en avant est séparée de la partie restante des feuilles de la pile de feuilles à l'aide desdits moyens de séparation pendant l'avance ou pendant l'inversion de la pile de feuilles, et
    ladite feuille séparée située le plus en avant est transportée par lesdits seconds moyens de transport dans le sens d'avance des feuilles.
  2. Appareil d'alimentation en feuilles selon la revendication 1, dans lequel
    lesdits moyens de commande (33) sont des moyens destinés à actionner
    lesdits premiers moyens de transport (28a, 28b) pour transporter la pile de feuilles dans le sens d'avance des feuilles afin de séparer la feuille située le plus en avant des autres feuilles.
  3. Appareil d'alimentation en feuilles selon la revendication 2, dans lequel
    lesdits moyens de commande (33) sont des moyens destinés à commander lesdits premiers moyens de transport (28a, 28b) d'une manière telle que,
    lesdits premiers moyens de transport sont arrêtés après que la feuille séparée par lesdits moyens de séparation (37, 38) a commencé à être transportée par lesdits seconds moyens de transport (32a, 32b).
  4. Appareil d'alimentation en feuilles selon la revendication 2 ou 3, dans lequel
    lesdits premiers moyens de transport (28a, 28b) transportent la feuille en la pinçant.
  5. Appareil d'alimentation en feuilles selon la revendication 2 ou 3, dans lequel
    lesdits seconds moyens de transport transportent la feuille en la pinçant.
  6. Appareil d'alimentation en feuilles selon la revendication 2 ou 3, dans lequel
    lesdits moyens de séparation (37, 38) guident la feuille située le plus à l'extérieur et d'autres feuilles dans la pile de feuilles pendant qu'elles sont transportées par lesdits premiers moyens de transport (28a, 28b) dans des directions différentes.
  7. Appareil d'alimentation en feuilles selon l'une des revendications 1 à 6, dans lequel
    lesdits moyens de séparation (37, 38) comprennent un élément de séparation (38) ayant une extrémité libre effilée insérée entre la feuille située le plus à l'extérieur et d'autres feuilles dans la pile de feuilles transportées par lesdits premiers moyens de transport (28a, 28b) pour séparer la feuille située le plus à l'extérieur des autres feuilles.
  8. Appareil d'alimentation en feuilles selon la revendication 7, dans lequel
    ladite extrémité libre dudit élément de séparation (38) est sollicitée contre une partie de surface de la feuille située le plus à l'extérieur qui est opposée aux autres feuilles mais n'est pas en contact avec les autres feuilles, afin de séparer la feuille située le plus à l'extérieur des autres feuilles dans la pile de feuilles pendant qu'elles sont transportées par lesdits premiers moyens de transport (28a, 28b).
  9. Appareil d'alimentation en feuilles selon la revendication 8, comprenant en outre un élément de guidage (30, 31) destiné à guider une surface de ladite feuille située le plus en avant qui n'est pas en contact avec ledit élément de séparation (38), ledit élément de guidage ayant une partie évidée (20 ; 71) destinée à recevoir la feuille qui fléchit sous l'effet du contact entre la feuille et ledit élément de séparation.
  10. Appareil d'alimentation en feuilles selon la revendication 2, dans lequel
    lesdits moyens de commande (33) sont des moyens destinés à commander lesdits premiers moyens de transport (28a, 28b) d'une manière telle que
    lesdits premiers moyens de transport sont actionnés pour transporter les autres feuilles dans le sens inverse après que la feuille située le plus à l'extérieur, séparée par lesdits moyens de séparation (37, 38), a commencé à être transportée par lesdits seconds moyens de transport (32a, 32b).
  11. Appareil d'alimentation en feuilles selon l'une des revendications 1, 2 et 10, comportant en outre
    des moyens de guidage (30, 30a, 31, 31a) disposés entre lesdits premiers et seconds moyens de transport (28a, 28b ; 32a, 32b), lesdits moyens de guidage, tout en coopérant avec lesdits moyens de séparation (37, 38 ; 50-52), étant conçus pour guider la feuille située le plus en avant ou les autres feuilles dans la pile de feuilles transportée par lesdits premiers moyens de transport (28a, 28b) vers une position dans laquelle ladite feuille située le plus à l'extérieur ou lesdites autres feuilles ne sont pas transportées par lesdits premiers moyens de transport.
  12. Appareil d'alimentation en feuilles selon la revendication 11, dans lequel
    lesdits moyens de guidage (30, 30a ; 31, 31a) guident la feuille située le plus à l'extérieur et les autres feuilles dans la pile de feuilles transportée par lesdits premiers moyens de transport (28a, 28b) dans des directions différentes.
  13. Appareil d'alimentation en feuilles selon la revendication 11, dans lequel
    lesdits moyens de séparation comprennent un élément de séparation (38 ; 50 ; 51 ; 52) inséré entre la feuille située le plus à l'extérieur et les autres feuilles dans la pile de feuilles en cours de transport par lesdits premiers moyens de transport (28a ; 28b) pour guider la feuille.
  14. Appareil d'alimentation en feuilles selon la revendication 13, dans lequel
    ledit élément de séparation (38 ; 50 ; 51 ; 52) est sollicité contre une partie de surface de la feuille située le plus à l'extérieur qui est opposée aux autres feuilles mais n'est pas en contact avec les autres feuilles, afin de guider la feuille.
  15. Appareil d'alimentation en feuilles selon la revendication 14, dans lequel
       lesdits moyens de guidage comportent
    un élément de guidage (30 ; 31) destiné à guider une surface de ladite feuille située le plus en avant qui n'est pas en contact avec ledit élément de séparation (38), ledit élément de guidage ayant une partie évidée (20 ; 71) destinée à recevoir la feuille qui fléchit sous l'effet du contact entre la feuille et ledit élément de séparation.
  16. Système de formation d'images comportant :
    un moyen contenant (10) destiné à contenir des feuilles (P) ;
    un moyen d'introduction (11) pour faire sortir la feuille contenue dans ledit moyen contenant ;
    un moyen (39) de formation d'image destiné à former une image sur la feuille sortie par ledit moyen d'introduction ;
    un moyen d'empilage (25 ; 42) destiné à empiler les feuilles sur lesquelles les images sont formées par ledit moyen de formation d'image, d'une manière échelonnée en décalant chaque feuille d'une distance prédéterminée dans un sens prédéterminé ; et
    un appareil d'alimentation en feuilles selon l'une des revendications 1 à 15.
  17. Procédé d'alimentation en feuilles, comprenant les étapes dans lesquelles :
    on sépare une feuille (P1) située le plus en avant d'une pile de feuilles comportant des feuilles empilées en échelons d'une longueur prédéterminée dans un sens d'avance de feuilles, depuis la partie restante des feuilles de ladite pile de feuilles, tandis que la partie restante des feuilles est serrée par des premiers moyens de transport, en insérant un élément de séparation (38) entre la feuille située le plus en avant et la partie restante des feuilles, tandis que ladite pile de feuilles est transportée par lesdits premiers moyens de transport ; et
    on transporte la feuille séparée, située le plus en avant, à l'aide de seconds moyens de transport, tandis que la partie restante des feuilles est serrée par lesdits premiers moyens de transport afin d'en restreindre le mouvement.
EP19900124469 1989-12-18 1990-12-17 Appareil d'alimentation en feuilles Expired - Lifetime EP0433952B1 (fr)

Applications Claiming Priority (12)

Application Number Priority Date Filing Date Title
JP327819/89 1989-12-18
JP32781989 1989-12-18
JP1327819A JPH03186577A (ja) 1989-12-18 1989-12-18 シート搬送装置
JP34386589 1989-12-29
JP343865/89 1989-12-29
JP1343865A JP2825891B2 (ja) 1989-12-29 1989-12-29 シート搬送装置
JP2016585A JP2648521B2 (ja) 1990-01-26 1990-01-26 シート搬送装置
JP16585/90 1990-01-26
JP1658590 1990-01-26
JP2776190 1990-02-07
JP27761/90 1990-02-07
JP2027761A JP2648523B2 (ja) 1990-02-07 1990-02-07 シート搬送装置

Publications (3)

Publication Number Publication Date
EP0433952A2 EP0433952A2 (fr) 1991-06-26
EP0433952A3 EP0433952A3 (en) 1992-01-29
EP0433952B1 true EP0433952B1 (fr) 1999-08-18

Family

ID=27456605

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900124469 Expired - Lifetime EP0433952B1 (fr) 1989-12-18 1990-12-17 Appareil d'alimentation en feuilles

Country Status (2)

Country Link
EP (1) EP0433952B1 (fr)
DE (1) DE69033250T2 (fr)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4573789A (en) * 1982-04-13 1986-03-04 Minolta Camera Kabushiki Kaisha Duplex copying system
EP0303276B1 (fr) * 1987-08-12 1994-11-30 Canon Kabushiki Kaisha Appareil pour convoyer des feuilles et procédé pour convoyer des feuilles

Also Published As

Publication number Publication date
DE69033250D1 (de) 1999-09-23
EP0433952A2 (fr) 1991-06-26
EP0433952A3 (en) 1992-01-29
DE69033250T2 (de) 2000-04-20

Similar Documents

Publication Publication Date Title
US5008713A (en) Sheet conveying apparatus and sheet conveying method
JP4596603B2 (ja) シート取扱い装置
US6168153B1 (en) Printer sheet deskewing system with automatically variable numbers of upstream feeding NIP engagements for different sheet sizes
US5305995A (en) Sheet feeding apparatus for re-feeding a sheet without smearing
EP0623857A2 (fr) Dispositif pour éviter des vides de copiage en compilant en ligne
US6286831B1 (en) Optimized passive gate inverter
JPH0853252A (ja) ディスクタイプシートスタック装置及びディスクタイプシートスタック装置を含む静電写真印刷機
US4881729A (en) Recirculating document handler with integral SADH
US6398212B1 (en) Sheet surface reversing device and image forming apparatus having the same
US5090675A (en) Apparatus for automatically transporting sheets of orginal
EP1055623B1 (fr) Dispositif d'alimentation de feuilles avec moyen de réglage latéral
EP0457302A2 (fr) Appareil automatique d'enregistrement recto verso
EP0433952B1 (fr) Appareil d'alimentation en feuilles
JPS6251521A (ja) 給紙装置の用紙レジスト方法
US20220185617A1 (en) Sheet processing apparatus and image forming system
JP2648521B2 (ja) シート搬送装置
JP2825891B2 (ja) シート搬送装置
JP2846914B2 (ja) シート搬送装置
JP2966147B2 (ja) シート搬送装置
JP2692868B2 (ja) シート搬送装置
JPH05147831A (ja) 給紙装置
EP0927913B1 (fr) Dispositif d'alimentation des feuilles de copie à double face et son procédé associé d'opération
JPH1072127A (ja) 原稿送り装置
JPH03243571A (ja) 画像形成装置
JPS63171722A (ja) 記録シ−ト搬送装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19910102

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE FR GB IT

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR GB IT

17Q First examination report despatched

Effective date: 19940307

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT

REF Corresponds to:

Ref document number: 69033250

Country of ref document: DE

Date of ref document: 19990923

ITF It: translation for a ep patent filed
ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20051208

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20051214

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20051215

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20061231

Year of fee payment: 17

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20070703

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20061217

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20070831

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20061217

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20070102

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20071217