EP0487923B1 - Sheet feeding apparatus - Google Patents

Sheet feeding apparatus Download PDF

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Publication number
EP0487923B1
EP0487923B1 EP19910118559 EP91118559A EP0487923B1 EP 0487923 B1 EP0487923 B1 EP 0487923B1 EP 19910118559 EP19910118559 EP 19910118559 EP 91118559 A EP91118559 A EP 91118559A EP 0487923 B1 EP0487923 B1 EP 0487923B1
Authority
EP
European Patent Office
Prior art keywords
sheet
rotary feed
feed means
roller
rotary
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
EP19910118559
Other languages
German (de)
English (en)
French (fr)
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EP0487923A1 (en
Inventor
Kenji C/O Canon Kabushiki Kaisha Kawazoe
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
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Filing date
Publication date
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Publication of EP0487923A1 publication Critical patent/EP0487923A1/en
Application granted granted Critical
Publication of EP0487923B1 publication Critical patent/EP0487923B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J15/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in continuous form, e.g. webs
    • B41J15/005—Forming loops or sags in webs, e.g. for slackening a web or for compensating variations of the amount of conveyed web material (by arranging a "dancing roller" in a sag of the web material)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J13/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets
    • B41J13/10—Sheet holders, retainers, movable guides, or stationary guides
    • B41J13/103—Sheet holders, retainers, movable guides, or stationary guides for the sheet feeding section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J13/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets
    • B41J13/26—Registering devices
    • B41J13/32—Means for positioning sheets in two directions under one control, e.g. for format control or orthogonal sheet positioning

Definitions

  • the present invention relates to a sheet feeding apparatus according to the preamble of claim 1.
  • sheet feeding apparatus is provided for feeding a sheet (copy sheet, transfer sheet, photosensitive sheet, electrostatic recording sheet, print sheet, OHP sheet, envelope, post card, sheet original or the like) rested on a sheet containing portion (sheet stacking platform, sheet stacking tray, sheet stacking deck, removable sheet supply cassette, manual sheet supply platform or the like) or a sheet manually supplied to the sheet containing portion one by one to a sheet treatment portion such as an image forming station, exposure station, treating station or the like in an image forming system such as a copying machine, facsimile and the like or a recording system (printer) acting as an information output equipment of a word processor, personal computer and the like.
  • a sheet feeding apparatus for feeding a sheet (copy sheet, transfer sheet, photosensitive sheet, electrostatic recording sheet, print sheet, OHP sheet, envelope, post card, sheet original or the like) rested on a sheet containing portion (sheet stacking platform, sheet stacking tray
  • a sheet support plate (sheet guiding means) 6 acting as a sheet containing portion (sheet stacking means) is disposed so that a front end thereof is inclined downwardly.
  • An urging plate (intermediate plate) 8 is disposed above an upper surface of the sheet support plate and is always floated from the upper surface of the plate 6 by a biasing force of a spring member 8a.
  • Sheet separating pawls (sheet separating means) 7 are arranged at front corners of the sheet support plate for separating a single sheet from the other sheets.
  • the sheets 5 (copy sheets or recording media) are stacked on the sheet support plate 6 so that leading ends of the sheets are regulated or locked by the separating pawls 7.
  • a sheet supply roller 9 acting as a sheet supply means serves to afford a feeding force to the sheets stacked on the plate 6 and comprises a shaft portion 9a and a roller portion 9b integrally formed with the shaft portion.
  • An uppermost sheet on the sheet stack 5 stacked on the plate 6 is urged against the roller portion 6a of the sheet supply roller 9 by the urging plate 8 biased upwardly by means of the spring member 8a.
  • a sheet feed roller (sheet relay convey means) 16 is arranged ahead of the sheet support plate 6 in a sheet feeding direction and comprises a shaft portion 16b and a roller portion 16a integrally formed with the shaft portion.
  • a sheet guide plate 26 is disposed between the sheet support plate 6 and the sheet feed roller 16 so that a leading end thereof is inclined downwardly, which sheet guide plate serves to guide the sheet 5 below the sheet feed roller 16.
  • the leading end portion of the sheet guide plate 26 is arcuated to conform with a lower half surface of the roller portion 16a of the sheet feed roller 16 and to extend to the left side of the sheet feed roller.
  • First and second pinch rollers 17A and 17B are urged against the lower portion of the sheet feed roller 16 by respective spring members (not shown) at two upstream and downstream points along the sheet feeding direction, respectively. These pinch rollers are contacted with the sheet feed roller 16 through openings 26a formed in the arcuated leading end portion of the sheet guide plate 26, respectively, and are driven by the rotational movement of the sheet feed roller 16.
  • a platen bar 15 is disposed tangentially to the sheet feed roller 16 in the vicinity of the latter at the left side thereof.
  • a reciprocable carriage 11 can be reciprocally shifted in parallel with the platen bar 15 by means of a guide rail and a drive means (both not shown).
  • a recording head 12 and an ink ribbon cassette 13 are mounted on the carriage 11, and the recording head 12 is opposed to the platen bar 15 with the interposition of an ink ribbon 14.
  • the sheet supply roller 9 When the sheet supply roller 9 is rotated in a clockwise direction, the uppermost sheet on the sheet stack 5 stacked on the sheet support plate 6 is subjected to the sheet feeding force, with the result that the front corner portions of the uppermost sheet ride on the separating pawls 7 to be unlocked by the separating pawls, thus separating the uppermost sheet alone from the other sheets.
  • the separated uppermost sheet is guided by the sheet guide plate 26 to reach a nip between the sheet feed roller 16 and the first pinch roller 17A.
  • the uppermost sheet 5 is fed by the sheet feed roller 16 and the first pinch roller 17A between the arcuated end portion of the guide plate 26 and the lower surface of the sheet feed roller 16, and then is fed by the sheet feed roller 16 and the second pinch roller 17B between the arcuated end portion of the guide plate 26 and the lower surface of the sheet feed roller 16, so that the leading end of the sheet enters into a space between the platen bar 15 and the ink ribbon 14.
  • the rotational movement of the sheet feed roller 16 is changed to an intermittent rotational drive control wherein the sheet is fed by one printing line space, and the control of the reciprocal shifting movement of the carriage 11, head-down/head-up control of the recording head 12, the feed control of the ink ribbon 14 and the like are executed in co-relation with each other by means of a record control circuit (not shown), thus performing the recording operation with respect to the sheet 5 per one line.
  • the actuation of the sheet supply roller 9 may be linked with the activation of the sheet feed roller 16 by means of a feed motor (not shown).
  • a clutch is disposed between the sheet supply roller 9 and the feed motor to switch over the activation between the sheet supply roller and the sheet feed roller. It is a most simplified method that the switching of the clutch is effected by rotating the feed motor in a direction opposite to a normal direction in which the feed motor is rotated when the sheet is supplied.
  • the leading end of the sheet 5 is sent to the nip between the sheet feed roller 16 and the first pinch roller 17A by the rotation of the sheet supply roller 9.
  • the feed motor is switched to be rotated reversely.
  • the clutch connnection between the feed motor and the sheet supply roller 9 is disengaged by the reverse rotation of the feed motor, thus stopping the sheet supply roller 9.
  • the sheet feed roller 16 is rotated in a reverse direction Q opposite to the sheet feeding direction P, so that the sheet fed by the predetermined distance through the nip between the feed roller 16 and the first pinch roller 17A is fed back until the leading end of the sheet passes through the nip between the feed roller 16 and the first pinch roller 17A.
  • a bent loop (as shown by the solid line) is formed in a sheet portion between the stationary sheet supply roller 9 and the nip (between the feed roller 16 and the first pinch roller 17A) in opposition to the resiliency of the sheet.
  • the object of the present invention is to provide a sheet feeding apparatus which can surely correct the skew-feed of a sheet regardless of the resiliency of the sheet and without damaging the sheet and properly feed the sheet.
  • a sheet feeding apparatus comprising the features of claim 1 and in particular comprising, a sheet supporting means for stacking and supporting sheets, a rotary sheet supply means for feeding out the sheets stacked on the sheet supporting means, a rotary feed means for feeding the sheet in normal and reverse directions by pinching the sheet into a nip of the rotary feed means, and a rotation control means for prohibiting a reverse rotation of the rotary sheet supply means if a reverse rotational load applied from the fed sheet to the rotary sheet supply means is below a predetermined value and for permitting the reverse rotation of the rotary sheet supply means while applying a brake load to the rotary sheet supply means if the reverse rotational load is above the predetermined value, when the sheet is fed in a reverse direction toward the rotary sheet supply means by means of the rotary feed means.
  • a skew-feed of the sheet is corrected by the feeding of the sheet in the reverse direction by means of the rotary feed means and the control of the rotation of the rotary sheet supply means by
  • a sheet feeding apparatus comprising the features of claim 1 and in particular comprising a sheet supporting means for stacking and supporting sheets, a rotary sheet supply means for feeding out the sheets stacked on the sheet supporting means, a rotary feed means for feeding the sheet in normal and reverse directions by pinching the sheet into a nip of the rotary feed means, and a biasing means for rotatingly biasing the rotary sheet supply means toward a sheet feeding direction; and wherein a skew-feed of the sheet is corrected by the feeding of the sheet in the reverse direction by means of the rotary feed means and a biasing force of the biasing means regarding the rotary sheet supply means.
  • This embodiment is embodied as a word processor to which the sheet feeding apparatus according to the present invention is applied.
  • Fig. 1 is a perspective view of the word processor.
  • the word processor comprises a key board portion 1 for inputting information, a display portion 2 including a CRT for displaying the information, a recording device portion (printer portion) 3 for recording the information on a sheet (recording sheet) acting as a recording medium, and a sheet feeding apparatus portion (referred to as “sheet supply device portion” or “sheet supply device” hereinafter) 4.
  • Figs. 2 and 3 are partially sectional perspective views showing internal constructions of the sheet supply device portion 4 and the recording device portion 3, respectively.
  • Fig. 4 shows a sheet feeding path from the sheet supply device portion 4 to the recording device portion 3, as already described.
  • the sheet supply device 4 serves to separate and feed, by means of a sheet supply roller 9 serving as a first rotary feed means and separating pawls 7, an uppermost sheet on a sheet stack 5 stacked on a sheet support plate 6 which is inclined forwardly and downwardly.
  • the sheet supply roller 9 acting as a sheet supply means is rotatably supported by side frames 19 of the sheet support plate 6 at both ends of a shaft portion 9b of the roller.
  • a drive transmitting means 10 (Figs. 2, 8 and 9) which will be described later is disposed at one end of the shaft portion 9b of the sheet supply roller and is connected to a feed motor (Fig. 3) which acts as a sheet feed drive means of the recording device 3 and will be described later.
  • Fig. 5 shows a positional relation between the sheet supply roller 9 of the sheet supply device 4 and a sheet feed roller 16 of the recording device 3, wherein said sheet feed roller serves as a second rotary feed means.
  • the sheet supply roller 9 comprises a single roller portion 9a fixedly mounted on the shaft portion 9b at a longitudinal central portion thereof, and the sheet feed roller 16 comprises a pair of roller portions 16a fixedly mounted on a shaft portion 16b on both sides of a longitudinal central portion thereof, so that the roller portion 9a of the sheet supply roller 9 is positioned between the two roller portions 16a of the sheet feed roller 16.
  • Fig. 5 shows a condition that the sheet 5 separated from the sheet supply device 4 is skew-fed and reaches a nip between the sheet feed roller 16 and a first pinch rollers 17A.
  • the leading end of the sheet 5 which was skew-fed is registered with the longitudinal direction of the left and right roller portions 16a of the sheet feed roller 16.
  • the sheet feed roller is then rotated in the normal direction P, the sheet 5 is fed to the aforementioned recording head (recording portion) 12 without the skew-feed of the sheet.
  • the sheet 5 when the sheet 5 has greater resiliency, the sheet 5 is rotated in an anti-clockwise direction C in Fig. 6 around a contacting point between the sheet and the sheet supply roller 9 by the returning movement A of the right corner 5R of the sheet 5 due to the reverse rotation of the sheet feed roller 16, until the right corner 5R of the sheet 5 is disengaged from the nip between the right roller portion 16a and the first pinch rollers 17A.
  • the leading edge of the sheet 5 is abutted against both nip between the left roller portion 16a and the first pinch rollers 17A and nip between the right roller portion 16a and the first pinch rollers 17A, as shown by the phantom line 5b in Fig. 6.
  • the leading end of the sheet 5 which was skew-fed is registered with the longitudinal direction of the left and right roller portions 16a of the sheet feed roller 16.
  • the sheet feed roller is then rotated in the normal direction P, the sheet 5 is fed to the recording head 12 without the skew-feed of the sheet.
  • the friction force is determined by urging force between the sheet supply roller 9 and the sheet 5 and a coefficient of friction of the sheet supply roller 9, and, further, such urging force and coefficient of friction are determined by a force required to separate the sheets 5 one by one.
  • the urging force between the sheet supply roller 9 and the sheet 5 is set to have a value of 200 - 500 grams, and the coefficient of friction of the sheet supply roller 9 is set to have a value of 1 - 1.5. If the urging force is weaker, it is impossible or unreliable to separate the sheets one by one; whereas, in the urging force is stronger, two or more sheets will be fed at a time (double-feed of the sheets).
  • the drive transmitting means 10 comprising a sheet supply gear 10a, clutch 10b, clutch gear 10c and the like is arranged at one end of the shaft portion 9b of the sheet supply roller 9.
  • the sheet supply gear 10a is coaxially and fixedly mounted on the shaft portion 9b
  • the clutch 10b comprises a tubular member coaxially and freely rotatably mounted on the shaft portion 9b
  • the clutch gear 10c is also coaxially and freely rotatably mounted on the shaft portion 9b.
  • the clutch 10b is positioned radially outwardly of the sheet supply gear 10a in coaxial with the latter.
  • a clutch pawl 10d is rockably mounted on a surface of the clutch gear 10c which faces toward the clutch 10b, so that, when the clutch gear 10c is rotated, a free end of the clutch pawl 10d slides on a peripheral surface of the cylindrical clutch 10b.
  • the clutch pawl 10d is always biased toward the clutch 10b by means of a spring (not shown) and can be shifted along its pivot to some extent.
  • Fig. 8 shows a clutch ON condition, wherein the free end of the clutch pawl 10d is fallen into a notch opening 10e formed in the peripheral surface of the clutch 10b to engage with the sheet supply gear 10a.
  • a relay gear train G only the last one of gear train is shown
  • the rotation of the clutch gear 10c is transmitted to the sheet supply gear 10a, with the result that the sheet supply roller 9 is rotated in the sheet feeding direction shown by the arrow e.
  • Fig. 9 shows a clutch OFF condition, wherein the clutch pawl 10d is disengaged from the sheet supply gear 10a due to the reverse rotation of the feed motor 18.
  • Fig. 10A is a development view of the peripheral surface of the clutch 10b
  • Figs. 10B and 10C are sectional views of the clutch taken along the lines B - B and C - C, respectively.
  • stopper surfaces HP1, HP2 are formed on the peripheral surface of the clutch 10b.
  • a symbol S1 denotes the above-mentioned notch opening 10e.
  • the direction in which the clutch pawl 10d moves from the stopper HP2 to the stopper HP1 corresponds to the sheet feeding direction (normal direction), and the direction in which the clutch pawl 10d moves from the stopper HP2 to the stopper HP1 corresponds to the reverse direction.
  • the initialisation operation is performed so that the clutch pawl 10d is shifted up to the stopper surface HP1.
  • a distance between the stopper surface HP1 and the notch opening S1 is constant (corresponding to four printing lines in the illustrated embodiment), and, accordingly, so long as the clutch pawl 10d is positioned at the stopper HP1, it is easy to surely shift the clutch pawl into the notch opening S1.
  • the clutch pawl 10d is positioned in an area between the notch opening S1 and the border Lb, when the clutch pawl 10d is shifted toward the stopper HP1, the clutch pawl 10d is inserted into the notch opening S1 to establish the clutch ON condition. To avoid this, the initialization operation is performed after the clutch pawl 10d is initially shifted to the stopper HP2.
  • the initialization operation can be effected by shifting the clutch pawl 10d to the stopper HP2 and then by shifting the clutch pawl toward the stopper HP1.
  • the reference numeral 9c denotes a tightening spring acting as a drive control means (torque limiter) mounted on one end of the shaft portion 9b of the sheet supply roller 9.
  • One end 9c 1 (Figs. 11 and 12) of the spring 9c is fixedly sandwiched between two projections 19a formed on the frame 19.
  • the spring 9c acting as the torque limiter permits the normal rotation (to the direction e in Figs. 8 and 11) of the sheet supply roller 9 without any load when a sheet feeding force to the normal direction e acts on the sheet supply roller 9 and prohibits the reverse rotation (to a direction f in Fig. 12) of the sheet supply roller 9 when a sheet feeding force to the reverse direction f acts on the sheet supply roller 9 by decreasing an inner diameter of the spring 9c.
  • the force of the spring 9c by which the shaft portion 9b is tightened is greater than the maximum sheet feeding force during the feeding and separating of the single sheet 5 by means of the sheet supply roller 9 and is smaller than a sheet feeding force generated by the sheet feed roller 16 and the pinch rollers 17A, 17B.
  • the reference numeral 9d denotes a clutch lever acting as a means for changing the operating force of the torque limiter on the basis of the kind of sheets to be used and/or temperature/humidity in the apparatus.
  • the clutch lever 9d is rotatably supported by the shaft portion 9b of the sheet supply roller, and a free end of the lever is provided with a toothed portion 9d 1 arranged along a circle having a center positioned at the shaft portion 9b, which toothed portion is meshed with a gear 9f rotatably mounted on the frame 19.
  • the gear 9f can be reversibly rotated by clutch motor (not shown), so that the normal and reverse rotations of the gear 9f cause the normal and reverse rocking movements of the clutch level 9d around the shaft portion 9b, respectively.
  • the clutch 9d is provided with a projection 9e associated with the other end 9c 2 of the tightening spring 9c acting as the torque limiter.
  • the other end 9c 2 of the rotating spring 9c is abutted against the projection 9e to regulate an amount of the rotational movement of the other end 9c 2 , thus preventing the inner diameter of the spring 9c from being further decreased. That is to say, the projection 9e serves to limit the tightening force of the spring 9c acting on the shaft portion 9b.
  • the clutch lever 9d is rotated, since the positional relation between the projection 9e and the other end 9c 2 of the spring 9c is changed, it is possible to control the inner diameter of the spring 9c, and, thus, to control the tightening force of the spring 9c acting on the shaft portion 9b. Consequently, it is possible to change or vary a reverse rotational force of the sheet supply roller 9 provided by the sheet feeding force.
  • the sheet supply roller 9 When the sheet supply roller 9 is rotated by a predetermined time period after the leading end of the sheet 5 fed by the sheet supply roller 9 has just reached the nip between the sheet feed roller 16 and the first pinch rollers 17A urged against the sheet feed roller, the sheet feed roller 16 is rotated reversely until the leading end of the sheet is returned to the nip between the sheet feed roller 16 and the first pinch rollers 17A. As a result, the reverse rotation of the sheet supply roller 9 is prevented by the action of the torque limiter 9c attached to the shaft portion 99b of the sheet supply roller 9, so that a bent loop is formed in the sheet 5 between the sheet feed roller 16 and the sheet supply roller 9, as shown by the solid line in Fig. 4.
  • the leading end of the sheet 5 is urged against the nip between the sheet feed roller 16 and the first pinch rollers 17A due to the resiliency of the sheet itself.
  • this urging action it is possible to register the leading edge of the sheet with the longitudinal direction of the sheet feed roller 16, and, thus, to feed the sheet without any skew-feed of the sheet.
  • a thickness of the normal sheet is 40 - 100 ⁇ m and a thickness of the postcard is 230 ⁇ m, and, since the thickness of the postcard is greater than that of the normal sheet by about 2 - 5 times, the resiliency of the postcard greatly differs from that of the normal sheet.
  • the resiliency of the sheet varies with the humidity.
  • Two solid lines shown in Fig. 13 show the changes in load to the sheet supply roller 9 when the bent loops are formed under the humidity of 10 % and 80 %, respectively.
  • the minumum rotational load in the reverse direction acting on the sheet supply roller 9 should be greater than the sheet separating force.
  • the minimum load is set to a load shown by a chain and dot line (I) in Fig. 13.
  • the bent loop can be formed within a range defined by the solid line (IV), but, cannot be formed (as shown by the phantom line in Fig. 4) within a range defined by the solid line (III), with the result that the sheet supply roller 9 is rotated reversely or there arises the relative slipping movement between the sheet and the sheet supply roller 9, thus damaging the sheet.
  • the sheet supply roller 9 may comprise a pair of roller portions 9a.
  • the sheet supply roller may comprise a pair of roller portions 9a.
  • Temperature/humidity detection means (not shown) for detecting the temperature and humidity in the sheet supply device and the recording device used with the sheet supply device are disposed in the system in place.
  • the temperature detection means is constituted by a thermistor and the like
  • the humidity detection means is constituted by a humidity-sensitive element of electrostatic capacity type and the like.
  • the carriage 11 is slidably attached to a guide shaft 20 both ends of which are secured to a frame 21 of the recording device.
  • Driven pulleys (not shown) in synchronous with a carriage motor 22 are also rotatably attached to the frame 21, and a timing belt 23 extending between the driven pulleys is connected to the carriage 11.
  • a take-up shaft 24 mounted on the carriage 11 in place can receive a take-up core 13c of the ink ribbon cassette 13, so that, as the carriage 11 is shifted in the direction b, the ink ribbon 14 is taken-up wound around the take-up core.
  • the ink ribbon cassette 13 has a container 13a within which the take-up core 13c and a supply core 13c are rotatably received.
  • the ink ribbon 14 is wound on the supply core 13b.
  • the ink ribbon 14 extends from the supply core 13b and passes through a recess 13d of the container 13 to be exposed to the outside, and then extends to the take-up core 13c.
  • the ink ribbon 14 is constituted by an elongated film and heat-transferable (thermoplastic, thermosetting or thermosublimable) ink coated on the film. Further, the ink ribbon cassette 13 can be mounted on the carriage 11 by fitting it on locking projections 11a formed on the carriage 11. Incidentally, when the cassette 13 is mounted on the carriage 11, the take-up shaft 24 is inserted into the take-up core 13c so that the take-up core 13c is rotated by the rotation of the take-up shaft 24.
  • the recording means comprises a thermal recording head 12 which is constituted by a plurality of heat generating elements (which can be heated by applying electric currents to them) arranged in a line on a substrate.
  • the recording head 12 is mounted on the carriage 11 so that, when the ink ribbon cassette 13 is mounted on the carriage 11, the recording head 12 faces the recess 13d of the cassette. Further, the recording head 12 can be shifted up and down by a biasing means (not shown) such as a solenoid.
  • the recording head When the recording head is shifted down (head-down), it urges the ink-coated surface of the ink ribbon 14 against the sheet 5 backed-up by the platen 15; whereas, when the recording head is shifted up (head-up), the ink ribbon 14 is separated from the sheet 5.
  • the ink molten by the heat of the head is transferred onto the sheet 5, thus recording an image on the sheet.
  • a portion of the ink ribbon 14 used in the recording operation is wound around the take-up core 13c by the rotation of the take-up shaft 24.
  • the recording head 12 When one line recording is finished in this way, the recording head 12 is shifted up, the carriage 11 is returned to its home position, and the sheet 5 is fed by one line in the direction c.
  • the sheet feed means 16 for feeding the sheet 5 comprises the roller portions 16a and the pinch rollers 17, and the feed motor 18 is connected to the sheet feed roller 16 via the drive transmitting gear train.
  • the feed motor 18 is driven, the sheet feed roller 16 is rotated so that the sheet 5 supplied from the sheet supply device 4 is guided along the peripheral surface of the feed roller 16 and is fed in the direction c between the platen 15 and the ink ribbon 14.
  • Fig. 14 is a block diagram of the control system. This block diagram only shows a connecting relation between blocks, and the detailed control lines are omitted. Further, elements included within a broken line box constitute a CPU unit.
  • a CPU 30 is a central operation processing unit and serves to read out programs and various data from a ROM 31 and/or a floppy disc driver 32 (Fig. 1, described later) and to perform the required calculations and judgements to control various elements.
  • the ROM 31 is a read only memory and serves to store various programs for activating the CPU 30, and various data required for the recording, such as character codes, dot patterns (character generator CG) and the like.
  • a RAM 33 is a read/write memory and includes a working area where the data commanded by the CPU 30 and the calculation results are temporarily stored, a buffer area where various data from the key board 1, external interface portion 47 or floppy disc driver 32 are stored, and a text are where the documents or sentences are stored.
  • the CPU unit is connected to the printer unit 3 via a recording head driver 34, motor driver 35 and detection portion 36.
  • the recording head driver 34 drives the recording head 12 in the printer unit 3 under the control of the CPU 30, and the motor driver 35 drives the feed motor 18 (Fig. 3), carriage motor 22 (Fig. 3) and clutch motor of the sheet supply device 4 under the control of the CPU 30.
  • the detection portion 36 transmits detection information from a ribbon sensor provided in the printer unit 3 for detecting the presence of the ink ribbon or from a temperature/humidity detection sensor for detecting the temperature/humidity in the system to the CPU 30.
  • a power source 38 controls a drive voltage V H for the recording head 12, a drive voltage V M for the feed motor 18, carriage motor 22 and clutch motor, a drive voltage V FDD for the floppy disc driver 32, and a drive voltage V CC for other logic circuits.
  • a controller 39 performs various controls such as the transfer of the recording data of the recording head 12, the changing of the voltage/current of the drive source V H and the like, under the control of the CPU 30.
  • the keyboard 1 for inputting various data required for the recording and eddition is connected to the CPU unit via a keyboard connector (KBC) 40.
  • the display portion 2 including the CRT for displaying various information and data inputted from the keyboard 1 is also connected to the CPU unit via a CRT connector (CRTC) 41.
  • the display portion 2 may comprise a liquid crystal display or other display elements, in place of the CRT.
  • the floppy disc driver 32 is connected to the CPU unit via a floppy disc driver connector (FDDC) 42.
  • FDDC floppy disc driver connector
  • a hard disc or an external RAM can be used.
  • the CPU unit can be connected to an RS232C 44, sentronics 45 and MODEM 46 via interface connectors (IFC) 43 to perform the control of the recording device 3 under the control of an external control equipment and the communication to external equipments.
  • IFC interface connectors
  • the recording device 3 When the recording command is emitted, the recording device 3 firstly detects the temperature/humidity in the apparatus by the temperature/humidity detection means, and then judges the sheet information inputted from the keyboard 1 or detected by the means for the kind of sheet, and determines the rotational position of the clutch lever 9d for obtaining the optimum spring force of the torque limiter 9c (steps S1, S2, S3). Then, by driving the clutch motor, the clutch lever 9d is positioned to the determined position (step S4).
  • step S5 the clutch pawl 10d is shifted to the stopper surface HP1 (Fig. 10) (step S5).
  • step S6 the feed motor 18 is rotated reversely for 4 lines to shift the clutch pawl 10d from the stopper HP1 to the notch opening S1 (10e), thus establishing the clutch ON condition (Fig. 8) (step S6).
  • step S7 the sheet supply roller 9 is rotated to feed the sheet to the recording device 3 (step S7).
  • step S8 the feed motor is stopped.
  • step S9 the feed motor 18 is driven reversely to rotate the sheet feed roller 16 reversely.
  • step S10 the feed motor 18 is driven normally to feed the sheet until the sheet faces the recording portion of the recording head 12, and then the feed motor is stopped (steps S11, S12, S13).
  • the sheet can be fed to a desired position for the recording operation.
  • a power accumulating mechanism 9g - 9j acting as a biasing means operated only when the sheet supply roller 9 is subjected to the feeding force in the direction f opposite to the sheet feeding direction e is arranged between the sheet supply roller (sheet supply means) 9 and the drive transmitting means 10.
  • a spring holder 9h is attached to one end of the shaft portion 9b of the sheet supply roller via a one-way baring 9i, so that, when the sheet supply roller 9 is rotated in the driection f opposite to the sheet feeding direction e, the spring holder 9h can be rotated in the direction f through the one-way bearing 9i. Further, a spring 9g is provided, which spring has one end secured to a pin 9j formed integrally with the spring holder 9h and the other end secured to a projection 19b formed on the frame 19.
  • Fig. 18 shows a condition that the sheet supply roller 9 is rotated in the sheet feeding direction e (normal direction). In this condition, the sheet supply roller 9 is not subjected to the force of the power accumulating mechanism 9g - 9j in its rotational direction.
  • Fig. 19 shows a condition that the sheet supply roller 9 is rotated in the direction f (reverse direction) opposite to the sheet feeding direction.
  • the spring holder 9h is rotated in the direction f via the one-way bearing 9i in opposition to the spring 9g to charge the spring 9g, thus biasing the sheet supply roller 9 in the normal direction e.
  • the right corner 5R of the sheet 5 is pinched by the nip betwen the right roller portions 16a and the first pinch roller 17A, and right corner 5R of the sheet is fed back by thre returning movement A due to the reverse rotation of the sheet feed roller 16, thus disengaging the right corner of the sheet from the nip between the right roller portions 16a and the first pinch roller 17A.
  • the sheet feed roller 16 is then rotated in the normal direction P, the sheet 5 is fed to the recording portion 12 without the skew-feed of the sheet.
  • the sheet supply roller 9 reversely, it is possible to correct the skew-feed of the sheet.
  • step S1 When the recording command is emitted (step S1), the recording device firstly rotate the feed motor 18 reversely for 10 lines and then normally for 10 lines, thus shifting the clutch pawl 10d to the stopper surface HP1 (Fig. 10) (step S2). Then, the feed motor 18 is rotated reversely for 4 lines to shift the clutch pawl 10d from the stopper HP1 to the notch opening S1 (Fig. 10), thus establishing the clutch ON condition (step S3).
  • step S4 the sheet supply roller 9 is rotated to feed the sheet to the recording device.
  • step S5 the feed motor is stopped.
  • step S6 the feed motor 18 is driven reversely to rotate the sheet feed roller 16 reversely.
  • step S7 the feed motor 18 is stopped.
  • step S8 the feed motor 18 is driven normally to feed the sheet until the sheet faces the recording portion of the recording head 12, and then the feed motor 18 is stopped.
  • the sheet 5 can be fed to a desired position for the recording operation by means of the recording head 12.
  • the sheet feeding apparatus comprises the features of claim 1 and in particular comprises a sheet support means for stacking and supporting sheets, a rotary sheet supply means for feeding out the sheets stacked on the sheet support means, a rotary feed means for feeding the sheet in normal and reverse directions with respect to a sheet feeding direction by pinching the sheet into a nip of the rotary feed means, and a rotation control means for prohibiting a reverse rotation of the rotary sheet supply means.
  • the skew-feed of the sheet is corrected by the feeding of the sheet in the reverse direction by means of the rotary feed means and the control of the rotation of the rotary sheet supply means by means of the rotation control means.
EP19910118559 1990-10-31 1991-10-30 Sheet feeding apparatus Expired - Lifetime EP0487923B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP296725/90 1990-10-31
JP29672590 1990-10-31
JP3237468A JP2903796B2 (ja) 1990-10-31 1991-08-23 シート材給送装置及び画像形成装置
JP237468/91 1991-08-23

Publications (2)

Publication Number Publication Date
EP0487923A1 EP0487923A1 (en) 1992-06-03
EP0487923B1 true EP0487923B1 (en) 1996-07-31

Family

ID=26533216

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910118559 Expired - Lifetime EP0487923B1 (en) 1990-10-31 1991-10-30 Sheet feeding apparatus

Country Status (3)

Country Link
EP (1) EP0487923B1 (ja)
JP (1) JP2903796B2 (ja)
DE (1) DE69121173T2 (ja)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2271556B (en) * 1992-10-08 1997-01-15 Seiko Epson Corp Paper skew removal apparatus and a pronter using the same
US5524994A (en) * 1992-10-08 1996-06-11 Seiko Epson Corporation Paper skew removal apparatus and a printer using the same
DE69331898T2 (de) * 1992-12-28 2002-10-02 Canon Kk Bogenförderapparat
JP3530543B2 (ja) * 1993-02-25 2004-05-24 セイコーエプソン株式会社 単票紙のスキュー取り方法とその装置
JP3098369B2 (ja) * 1993-12-15 2000-10-16 キヤノン株式会社 シート給送装置及び記録装置
US5726613A (en) * 1995-02-01 1998-03-10 Nippon Telegraph And Telephone Corporation Active inductor

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2055768B (en) * 1979-07-30 1983-04-20 Ricoh Kk Automatic sheet feeding systems in printing apparatus
JPS62111772A (ja) * 1985-11-09 1987-05-22 Fujitsu Ltd プリンタにおける単票のセツト方法
JPS63130440U (ja) * 1987-02-18 1988-08-25

Also Published As

Publication number Publication date
JPH0524685A (ja) 1993-02-02
JP2903796B2 (ja) 1999-06-14
EP0487923A1 (en) 1992-06-03
DE69121173T2 (de) 1997-01-09
DE69121173D1 (de) 1996-09-05

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