US20060181009A1 - Automatic skew adjusting apparatus, image forming apparatus having the same and skew adjusting method thereof - Google Patents

Automatic skew adjusting apparatus, image forming apparatus having the same and skew adjusting method thereof Download PDF

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Publication number
US20060181009A1
US20060181009A1 US11/224,070 US22407005A US2006181009A1 US 20060181009 A1 US20060181009 A1 US 20060181009A1 US 22407005 A US22407005 A US 22407005A US 2006181009 A1 US2006181009 A1 US 2006181009A1
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United States
Prior art keywords
skew
skew adjusting
adjusting
positioning
shaft
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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US11/224,070
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English (en)
Inventor
Jong-Tae Kim
Hyun-seong Shin
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Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
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Assigned to SAMSUNG ELECTRONICS CO., LTD. reassignment SAMSUNG ELECTRONICS CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KIM, JONG-TAE, SHIN, HYUN-SEONG
Publication of US20060181009A1 publication Critical patent/US20060181009A1/en
Abandoned legal-status Critical Current

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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H9/00—Registering, e.g. orientating, articles; Devices therefor
    • B65H9/04—Fixed or adjustable stops or gauges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H9/00—Registering, e.g. orientating, articles; Devices therefor
    • B65H9/16—Inclined tape, roller, or like article-forwarding side registers
    • B65H9/166—Roller
    • 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
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0105—Details of unit
    • G03G15/0121—Details of unit for developing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46—Colour picture communication systems
    • H04N1/50—Picture reproducers
    • H04N1/506—Reproducing the colour component signals picture-sequentially, e.g. with reproducing heads spaced apart from one another in the subscanning direction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/30—Orientation, displacement, position of the handled material
    • B65H2301/33—Modifying, selecting, changing orientation
    • B65H2301/331—Skewing, correcting skew, i.e. changing slightly orientation of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
    • B65H2511/20—Location in space
    • B65H2511/24—Irregularities, e.g. in orientation or skewness

Definitions

  • the present invention relates to an image forming apparatus such as an electrophotographic printer. More particularly, the present invention relates to a skew adjusting apparatus capable of automatically adjusting a skew of a laser scanning unit (LSU) of an image forming apparatus, an image forming apparatus having such a skew adjusting apparatus and a skew adjusting method thereof.
  • LSU laser scanning unit
  • the LSU 11 forms an electrostatic latent image on the image forming surface 9 a according to a print data inputted from an external appliance such as a computer.
  • the electrostatic latent image formed by such an LSU 11 is developed into a toner image having a predetermined color as the electrostatic latent image passes through a developing unit.
  • the toner image is firstly transferred to an image transfer belt 17 by a first transfer roller 8 of a transfer unit 10 and then second transferred to a recording medium P such as a sheet of paper by a second transfer roller 23 .
  • the toner image transferred onto the medium P is fixed to the medium P by heat and pressure. Heat and pressure are applied from a heating roller 25 and a compressing roller 26 of a fixing unit 20 , respectively, and then the medium P is discharged to the outside of the printer.
  • the print quality of a wet type color laser printer 1 varies depending on a positional precision of the electrostatic latent image.
  • the image finally printed on the recording medium P will also be skewed. That is, it is necessary for light projected from an optical system (not shown) housed in the LSU body 15 of the LSU 11 to be scanned parallel in relation to the transverse direction of the photoconductor 11 onto the image forming surface 9 a of the photoconductor 9 as indicated by the dotted lines. If the light is scanned at a skewed angle ⁇ , an electrostatic latent image formed on the photoconductor 9 will be skewed and the resulting image will also be skewed.
  • a conventional LSU 11 comprises a skew adjusting unit 30 for adjustably securing a LSU body 15 to a base frame (not shown).
  • the skew adjusting unit 30 comprises an LSU anchoring plate 31 , an adjusting guide groove 39 , a sliding plate 35 , a skew adjusting shaft 37 , a shaft moving block 33 , and a tension spring 41 .
  • the LSU anchoring plate 31 has a top surface, on which an LSU body 15 is mounted.
  • the LSU body 15 serves to scan light onto a photoconductor (not shown) and contains an optical system (not shown) including a light source, a rotating multi-sided mirror, a plurality of lenses and a plurality of mirrors.
  • An adjustment guide groove 39 is arranged on one side of the underside of the LSU anchoring plate 31 .
  • the adjustment guide groove 39 has a guide surface 39 a having a predetermined skew angle.
  • the sliding plate 35 supports the LSU anchoring plate 31 in such a manner that the LSU anchoring plate 31 can rotate about a fixed axis (not shown) by a predetermined angle.
  • the skew adjusting shaft 37 is threaded into the shaft moving block 33 arranged on the sliding plate 35 adjacent to the adjustment guide groove 39 .
  • a first end 37 a of the skew adjusting shaft 37 is configured to contact with the guide surface 39 a of the adjustment guide groove 39 at a predetermined angle.
  • a second end 37 b of the skew adjusting shaft 37 includes a drive groove, so that a driver can rotate the skew adjusting shaft 37 .
  • the shaft moving block 33 is provided with a thread hole 33 a into which the skew adjusting shaft 37 is screwed.
  • the thread hole 33 a causes the first end 37 a of the skew adjusting shaft 37 to move forwards or backwards along the guide surface 39 a of the adjustment guide groove 39 depending on the rotating direction of the skew adjusting shaft 37 .
  • the tension spring 41 serves to exert an elastic force to the LSU anchoring plate 31 in such a way that the guide surface 39 a of the adjusting guide groove 39 in the LSU anchoring plate 31 moves into contact with the first end 37 a of the skew adjusting shaft 37 .
  • the tension spring 41 is disposed between the LSU anchoring plate 31 and the sliding plate 35 .
  • the skew adjusting unit 30 of the LSU 11 configured as described above, operates in the following manner.
  • a user may insert a driver into a driver groove on the second end 37 b of the skew adjusting shaft 37 . Then, the skew adjusting shaft 37 is rotated in a desired direction.
  • the user rotates the skew adjusting shaft 37 in a direction that causes the first end 37 a of the skew adjusting shaft 37 to advance toward the adjustment guide groove 39 (toward the left side in FIG. 3 ).
  • the first end 37 a of the skew adjusting shaft 37 pushes the guide surface 39 a against the elastic force exerted by the tension spring 41 .
  • the LSU body 15 rotates clockwise.
  • the user rotates the skew adjusting shaft 37 in a direction that causes the first end 37 a of the skew adjusting shaft 37 to retreat from the adjustment guide groove 39 (toward the right side in FIG. 3 ).
  • the first end 37 a of the skew adjusting shaft 37 releases the force exerted to the guide surface 39 a . Consequently, the LSU body 15 rotates counterclockwise by the elastic force of the tension spring 41 .
  • a conventional LSU 11 configured in this manner has drawbacks. For example, in order to adjust a skew of the LSU body 15 , the calculation of a rotation angle for rotating the skew adjusting shaft 37 and the rotation of the skew adjusting shaft 37 is typically performed manually.
  • calculating a rotation angle for rotating the skew adjusting shaft 37 usually requires outputting an image of a predetermined pattern to measure a skew difference of a color with reference to a certain color such as black. This is called the skew value and is typically used to calculate a rotation angle for rotating the skew adjusting shaft 37 .
  • the skew adjusting shaft 37 may be automatically rotated by using a power source such as a motor. In this event, however, because a motor is typically used for each LSU 11 , manufacturing costs increase.
  • Exemplary embodiments of the present invention address at least the above problems and/or disadvantages. Accordingly, exemplary implementations of the exemplary embodiments of the present invention provide skew adjusting apparatus capable of automatically adjusting a skew of an LSU of an image forming apparatus, an image forming apparatus having such an automatic skew adjusting apparatus and a skew adjusting method.
  • a skew adjusting apparatus including a plurality of skew adjusting parts arranged in a plurality of laser scanning units, respectively.
  • the automatic skew adjusting apparatus comprises a driving source, an actuating part arranged on a driving shaft of the driving source so that the actuating part selectively connects with one of the skew adjusting parts depending on a position to which the driving source moves.
  • the actuating part actuates the skew adjusting part connected with the actuating part as the driving shaft rotates.
  • a positioning part moves the driving source, and a power transmission part transmits or cuts off the power of the driving source to the positioning part so as to move the driving source or stop the movement of the driving source.
  • each skew adjusting part may comprise a skew adjusting shaft which adjusts a skew of a corresponding one of the laser scanning units via rotation, and an adjusting gear is arranged on the skew adjusting shaft.
  • the actuating part may comprise a plurality of worm gears vertically arranged to engage with the adjusting gear of each skew adjusting part.
  • the positioning part may comprise a positioning shaft having a first end with a positioning thread part and a positioning block having a positioning thread hole.
  • the positioning thread part may be received in or extracted from the positioning thread hole depending on the rotational direction of the positioning shaft.
  • a position detection part detects an amount the driving source moves. It is preferable that the position detection part comprise a linear encoder.
  • the positioning part may further comprise a sliding guide to support the driving source and guide the movement of the driving source.
  • a driving shaft guide may support the driving shaft of the driving source and guide the movement of the driving shaft.
  • the power transmission part comprises a clutch to interconnect or cut off the positioning shaft and the driving shaft.
  • the clutch comprises a first clutch plate connected to an end of the driving shaft in such a way of being capable of axially moving a predetermined distance.
  • a second clutch plate is connected to a second end of the positioning shaft.
  • An armature is arranged to move with the first clutch plate and a clutch coil generates magnetic force when electric current is applied to the clutch coil to move the armature.
  • a clutch spring returns the first clutch plate to its original position when no electric current is applied to the clutch coil.
  • automatic skew adjusting apparatus may further comprise a skew detection part which detects a skew of a laser scanning unit.
  • the skew detection part may comprise two skew detection sensors located on a plane which extends vertically from a skew reference line to a running direction of one of a transfer belt, a photoconductive belt and a photoconductive drum.
  • the skew detection sensors may be spaced from each other by a predetermined distance.
  • an image forming apparatus comprising a plurality of photoconductors, a plurality of scanning units which form an electrostatic latent image on the photoconductors, respectively, each scanning unit having a skew adjusting part, a plurality of developing units which develop the electrostatic latent image on the photoconductor into visible images, a transfer unit which transfers the images arranged on the respective photoconductors to a record medium, and an automatic skew adjusting unit which actuates the skew adjusting parts.
  • the automatic skew adjusting unit comprises a driving source, an actuating part arranged on a driving shaft of the driving source so that the actuating part can selectively connect with one of the skew adjusting parts depending on a position to which the driving source moves.
  • the actuating part actuates the skew adjusting part connected with the actuating part as the driving shaft rotates.
  • a positioning part moves the driving source and a power transmission part transmits or cuts off the power of the driving source to the positioning part so as to move the driving source or stop the movement of the driving source.
  • each skew adjusting part may comprise a skew adjusting shaft which adjusts a skew of a corresponding one of the laser scanning units via rotation, and an adjusting gear arranged on the skew adjusting shaft.
  • the actuating part comprises a plurality of worm gears vertically arranged to engage with the adjusting gear of each skew adjusting part.
  • the positioning part comprises a positioning shaft having a first end with a positioning thread part, a positioning block having a positioning thread hole, the positioning thread part being received in or extracted from the positioning thread hole depending on the rotational direction of the positioning shaft, and a position detection part which detects an amount the driving source moves.
  • the position detection part may also comprise a linear encoder.
  • the positioning part may further comprise a sliding guide which supports the driving source and guides the movement of the driving source.
  • a driving shaft guide supports the driving shaft of the driving source and guides the movement of the driving shaft.
  • the power transmission part may comprise a clutch which interconnects or cuts off the positioning shaft and the driving shaft.
  • the clutch may comprise a first clutch plate connected to an end of the driving shaft in such a way of being capable of axially moving by a predetermined distance and a second clutch plate connected to a second end of the positioning shaft.
  • An armature is movably arranged with the first clutch plate, a clutch coil generates magnetic force when electric current is applied to the clutch coil to move the armature.
  • a clutch spring returns the first clutch plate to its original position when no electric current is applied to the clutch coil.
  • the automatic skew adjusting unit may further comprise a skew detection part which detects a skew of a laser scanning unit.
  • the skew detection part may comprise two skew detection sensors located on a plane which extends vertically from a skew reference line to a running direction of a transfer belt, a photoconductive belt or a photoconductive drum.
  • the skew detection sensors may be spaced from each other by a predetermined distance.
  • a skew adjusting method for an image forming apparatus comprising the steps of forming an image of a predetermined pattern on a medium by using a plurality of laser scanning units, measuring a skew of each laser scanning unit, calculating a skew adjusting value of a skew adjusting part of each laser scanning unit, and adjusting the skew adjusting part of each laser scanning unit by using a driving source according to the calculated skew adjusting value.
  • the step of measuring the skew of each laser scanning unit may be performed by calculating a skew value by comparing time points of output skew detection signals for detecting an image from at least two skew detection sensors.
  • the skew detection sensors detect an image after the image formed by the respective laser scanning unit has been transferred to an image carrier.
  • the image carrier may be formed from a photoconductive belt, a transfer belt or a photoconductive drum.
  • the step of measuring a skew of the each laser scanning unit comprises measuring, on the basis of a reference pattern for forming an image or an image of a certain color, a skew value of an image of a color different from the reference pattern or the certain color and formed on the record medium by using a microscope. In this event, measuring step is performed after the medium formed with an image formed thereon is discharged out of the image forming apparatus.
  • the step of adjusting the skew adjusting part of each laser scanning unit may comprise connecting an actuating part for actuating the skew adjusting part with a skew adjusting part of an LSU to be adjusted, and adjusting the skew adjusting part of the LSU to be adjusted by operating the actuating part.
  • the step of connecting the actuating part with the skew adjusting part of the LSU to be adjusted may comprise reading out the position of the actuating part, and determining whether the read-out position of the actuating part conforms to the position of the skew adjusting part of the LSU to be adjusted. Then, the actuating part is moved to a position where the actuating part is connected with the skew adjusting part of the LSU to be adjusted according to the read-out position of the actuating part.
  • FIG. 1 is a diagrammatic view of a conventional wet type electrophotographic printer
  • FIG. 2 is a perspective view illustrating a skew phenomenon of a laser scanning unit of the wet type electrophotographic printer shown in FIG. 1 ;
  • FIG. 3 is a perspective view exemplifying a skew adjusting part of the laser scanning unit of the wet type electrophotographic printer shown in FIG. 1 ;
  • FIG. 4 is a perspective view of an automatic skew adjusting apparatus and a laser scanning unit according to an exemplary embodiment of the present invention, which are applicable to an image forming apparatus;
  • FIG. 5 is a perspective view of the laser scanning unit shown in FIG. 4 ;
  • FIG. 6 is a partial front view exemplifying the positional relationship of an actuating part of the automatic skew adjusting apparatus shown in FIG. 4 ;
  • FIG. 7 is a view showing partially in cross-section a clutch of a positioning part of the automatic skew adjusting apparatus shown in FIG. 4 ;
  • FIG. 8 is a conceptive illustration exemplifying the positional relationship of first and second skew detection sensors of the automatic skew adjusting apparatus shown in FIG. 4 ;
  • FIGS. 9A through 9G are front elevational views exemplifying the skew adjusting operation of the automatic skew adjusting apparatus shown in FIG. 4 ;
  • FIG. 10 is a flowchart exemplifying a process of the skew adjusting operation of the automatic skew adjusting apparatus shown in FIG. 4 .
  • An image forming apparatus such as, for example, a wet type color electrophotographic printer, performs print by processing print data transmitted from a computer (not shown).
  • An automatic skew adjusting apparatus according to an exemplary embodiment of the present invention is applicable to such image forming apparatuses.
  • a wet type color electrophotographic printer comprises four photoconductors (not shown) which form toner images of four colors such as black, cyan, magenta and yellow, respectively.
  • the printer comprises four LSUs which form electrostatic latent images corresponding to four colors onto the photoconductors, respectively, for example, black, cyan, magenta and yellow LSU's 111 K, 111 C, 111 M, 111 Y ( FIG. 4 ), four developing units (not shown) which develop the electrostatic latent images into toner images of four colors, respectively, a transfer belt 117 ( FIG.
  • an automatic skew adjusting apparatus 100 which automatically operates skew adjusting parts 130 K, 130 C, 130 M, 130 Y ( FIG. 5 ) for each one of the LSU's 111 K, 111 C, 111 M, 111 Y.
  • the construction and operation of the wet type color electrophotographic printer is substantially the same as with the conventional wet type color electrophotographic printer shown in FIG. 1 or other known wet type color electrophotographic printers and thus a more detailed description thereof will be omitted for purposes of clarity and conciseness.
  • FIG. 4 schematically shows an automatic skew adjusting apparatus 100 in accordance with an exemplary embodiment of the present invention.
  • the automatic skew adjusting apparatus 100 comprises a driving source 120 , an actuating part 140 , a positioning part 170 , a power transmission part 150 and a control part 201 .
  • the driving source 120 comprises a single driving motor 121 .
  • the driving motor 121 comprises a driving shaft 123 .
  • the driving motor 121 is movably supported on a sliding guide 180 of the positioning part 170 to be described later.
  • the actuating part 140 serves to selectively actuate the skew adjusting parts 130 K, 130 C, 130 M, 130 Y ( FIG. 5 ) installed in the black, cyan, magenta and yellow LSU's 111 K, 111 C, 111 M, 111 Y, respectively, and comprises first, second, third and fourth worm gears 141 K, 141 C, 141 M, 141 Y arranged on the driving shaft 123 .
  • the skew adjusting parts 130 K, 130 C, 130 M, 130 Y serve to adjust the skews of the LSUs 111 K, 111 C, 111 M, 111 Y, respectively, wherein the skew adjusting parts 130 K, 130 C, 130 M, 130 Y are arranged in the LSUs 111 K, 111 C, 111 M, 111 Y, respectively.
  • each skew adjusting part 130 K, 130 C, 130 M or 130 Y comprises an LSU anchoring plate 31 , an adjustment guide groove 39 , a sliding plate 35 , a skew adjusting shaft 137 K, 137 C, 137 M or 137 Y, a shaft moving block 33 , and a tension spring 41 .
  • any one of the skew adjusting part 130 K, 130 C, 130 M or 130 Y may be analogous to that of the skew adjusting part 30 of a conventional LSU 11 described above with reference to FIG. 3 , except for being provided with one of the skew adjusting shafts 137 K, 137 C, 137 M, 137 Y. Further detailed description thereof is omitted for purposes of clarity and conciseness.
  • Each skew adjusting shaft 137 K, 137 C, 137 M, 137 Y comprises a first end 139 a and a second end 139 b .
  • the first end 139 a is configured to contact with the guide surface 39 a of the adjustment guide groove 39 with a predetermined angle, for example, like the skew adjusting shaft 37 of the skew adjusting part 30 of the conventional LSU 11 described above with reference to FIG. 3 .
  • Each second end 139 b is formed with one of first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, or 138 C vertically engaged with worm gears 141 K, 141 C, 141 M, 141 Y of the actuating part 140 of the skew adjusting apparatus, respectively.
  • the skew adjusting parts 130 K, 130 C, 130 M, 130 Y are constructed by arranging the adjusting gears 138 K, 138 C, 138 M, 138 Y in, for example, a skew adjusting part as shown in FIG. 3 , respectively.
  • the skew adjusting parts 130 K, 130 C, 130 M, 130 Y can be constructed by arranging the adjusting gears 138 K, 138 C, 138 M, 138 Y with respect to other known skew adjusting parts (not shown) capable of adjusting a skew.
  • the first, second, third and fourth worm gears 141 K, 141 C, 141 M, 141 Y are vertically engaged with the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, 138 Y and have about the same width as each other.
  • first, second, third and fourth worm gears 141 K, 141 C, 141 M, 141 Y are formed on the driving shaft 123 in such a way that they can be engaged with corresponding skew adjusting parts 130 K, 130 C, 130 M and 130 Y, one by one, according to the axial position of the driving shaft 123 . That is, as shown in FIG. 6 , when the first worm gear 141 K is engaged with the first adjusting gear 138 K of the corresponding skew adjusting part 130 K, the second warm gear 141 C is arranged in a position spaced from the corresponding second adjusting gear 138 C by a distance about equal to the width of the second worm gear 141 C.
  • the third worm gear 141 M is arranged in a position spaced from the corresponding third adjusting gear 138 M by about a distance equal to two times of the width of the third worm gear 141 M
  • the fourth worm gear 141 Y is arranged in a position spaced from the corresponding third adjusting gear 138 Y by a distance about equal to three times of the width of the third worm gear 141 Y.
  • the positioning part 170 serves to move the driving motor 121 so that each worm gear 141 K, 141 C, 141 M or 141 Y of the actuating part 140 selectively connects to a corresponding one of the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M or 138 Y of a corresponding skew adjusting part 130 K, 130 C, 130 M or 130 Y.
  • the positioning part 170 comprises a positioning shaft 175 , a positioning block 171 and a position detection part 193 .
  • the positioning shaft 175 comprises a first end 175 a having a positioning thread part 176 and a second end 175 b including a driven clutch plate 153 which forms a clutch of a power transmission part 150 to be described later.
  • the positioning block 171 has a positioning thread hole 172 engaged with the positioning thread part 176 .
  • the positioning block 171 is secured to a main frame (not shown) of the printer.
  • the positioning thread part 176 may be partially engaged with the positioning thread hole 172 for support. Therefore, when the positioning thread part 176 is connected with the driving shaft 123 by the clutch 151 of the power transmission part 150 to be described later, the positioning shaft 175 is inserted into or extracted out of the positioning thread hole 172 according to the rotating direction thereof and moves in a direction indicated by arrow A or B of FIG. 4 .
  • the thread pitch of the positioning thread part 176 and the positioning thread hole 172 may be defined so that they are aobut equal to the thread pitch provided between the first, second, third and fourth worm gears 141 K, 141 C, 141 M, 141 Y and the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, 138 Y.
  • the adjusting gears 138 K, 138 C, 138 M or 138 Y are engaged with the first, second, third or fourth worm gear 141 K, 141 C, 141 M or 141 Y, respectively, in the direction indicated by arrow A or B in FIG. 4 , when the positioning shaft 175 is moved in the direction indicated by arrows A or B of FIG. 4 , due to threadable engagement between the positioning thread part 176 and the positioning thread hole 172 while the positioning shaft 175 is rotating.
  • the position detection part 193 serves to obtain positional information when the driving motor 121 is moved by the positioning part 170 .
  • the position detection part 193 comprises a linear encoder.
  • the linear encoder comprises a sensing hole part 195 and a photosensor 194 .
  • the sensing hole part 195 comprises a plurality of holes 195 a formed on a side wall of the sliding guide 180 with a predetermined space in the direction of moving the driving motor 121 .
  • the photosensor 194 is located at a side part of the driving motor 121 opposite to the sensing hole part 195 .
  • the photosensor 194 comprises a light emission part and a light reception part and generates a high or low signal due to the holes 195 a formed on the sliding guide 180 as the driving motor 121 is moved left or right by the positioning shaft 175 and the positioning block 171 of the positioning part 170 .
  • the linear encoder may comprise a film sheet (not shown) formed with marks in a predetermined space from each other and located on a side wall of the sliding guide 180 , and a photosensor (not shown) located on a side wall of the driving motor 121 .
  • the linear encoder may comprise a bar (not shown) alternately coated with magnetic materials of N and S poles and located on a side wall of the sliding guide wall 180 , and a hall sensor (not shown) mounted on the side wall of the driving motor 121 .
  • the linear encoder outputs a high or low signal to a control part 201 , and the control part 201 counts outputted high signals to calculate the moved position of the driving motor 121 , that is the position of the actuating part 140 .
  • the calculated positional information of the actuating part is stored in a memory 203 .
  • the positioning part 170 may further comprise a sliding guide 180 for securing the driving motor 121 and guiding the movement of the driving motor 121 , and a driving shaft guide 190 which supports the driving shaft 123 and guides the movement of the driving shaft 123 .
  • the driving sliding guide 180 may be manufactured from a plate having a substantially “C” shaped cross-section and secured to the main frame.
  • the driving shaft guide 190 includes a receiving hole 190 a which receives and supports the second end 123 b of the driving shaft 123 and is secured to the main frame of the printer.
  • the sliding guide 180 guides the movement of the driving motor 121 .
  • the driving motor 121 moves along with the positioning shaft 175 as the positioning shaft 175 is inserted into or extracted from the positioning thread hole 172 .
  • the driving motor 121 moves left or right as indicated by arrows A, B in FIG. 4 according to the rotating direction of the driving shaft 123 after the positioning shaft has been connected with the driving shaft 123 by the power transmission part 150 .
  • the power transmission part 150 serves to transmit the power of the driving motor 121 to the positioning part 170 so that the positioning part 170 can move the driving motor 121 .
  • the power transmission part 150 comprises a clutch 151 .
  • the clutch 151 interconnects or cuts off the positioning shaft 175 and the driving shaft 123 .
  • the clutch 151 comprises a driving clutch plate 152 , a driven clutch plate 153 , an armature 159 , a clutch coil 155 , and a clutch spring 157 .
  • the driving clutch plate 152 is secured to the first end 123 a of the driving shaft 123 by a guide key 158 in such a way that the driving clutch plate 152 can be axially moved over a predetermined distance as well as rotated along with the driving shaft 123 .
  • the driven clutch plate 153 is secured to the second end 175 b of the positioning shaft 175 by a fastener, for example, a screw.
  • the armature 159 may be formed from a cylindrical tube and connected to the driving clutch plate 152 via a bearing. Thus, the armature can move in the axial direction which is indicated by arrow A or B in FIG. 7 along with the clutch plate 152 . Because the bearing 163 is tightly interposed between a ridge 159 a arranged on the armature 159 and a protruded tube 152 a of the driving clutch plate 152 , the armature 159 does not rotate along with the driving shaft 123 .
  • the clutch coil 155 When electric current is applied to the clutch coil 155 , the clutch coil 155 generates magnetic force to draw the armature 159 in the direction indicated by arrow A in FIG. 7 . This makes the driving clutch plate 152 move into contact with the driven clutch plate 153 .
  • the clutch spring 157 is interposed between a first supporting ridge 123 c arranged on the tip of the first end 123 a of the driving shaft 123 and a second supporting ridge 152 b arranged on the internal circumferential surface of the driving clutch plate 152 .
  • the clutch spring 157 separates the driving plate 152 from the driven clutch plate 153 and returns the driving clutch plate 152 to its original position when electric current applied to the clutch coil 155 is cutoff. Consequently, magnetic force is lost.
  • the control part 201 calculates one or more skew adjusting values each required to adjust corresponding ones of the skew adjusting parts 130 K, 130 C, 130 M, 130 Y of the respective LSUs 111 K, 111 C, 111 M, 111 Y according to the first and second skew detection signals outputted from the first and second skew detection sensors 211 , 212 of the skew detection part 210 .
  • the control part 201 controls the operation of the driving motor 121 and the clutch 151 according to the adjusted skew values.
  • the first and second skew detection sensors 211 , 212 are located to be spaced from each other in a plane extending from a skew reference line L, which is vertical to a running direction of a transfer belt 117 .
  • the skew detection sensors 211 , 212 face the opposite edges of an image forming surface 117 a from the underneath of the transfer belt 117 .
  • the first and second skew detection sensors 211 , 212 detect toner images of respective colors of a predetermined pattern such as a straight line transferred onto the transfer belt 117 at two positions C, C′ on the skew reference line L.
  • the toner images transferred onto the transfer belt 117 are being moved to a second transfer roller (not shown), and then output first and second skew detection signals for respective colors to the control part 201 .
  • the time point that the first skew detection sensor 211 detects a toner image of a corresponding LSU and outputs the first skew detection signal becomes different from the time point that the second skew detection sensor 212 outputs the second skew detection signal as indicated by dotted lines in FIG. 8 .
  • control part 201 compares the time points of outputting the first and second skew signals and calculates the skew values of the respective LSUs 111 K, 111 C, 111 M, 111 Y on the basis of the difference in time point of outputting the first and second skew detection signals.
  • the control part 201 calculates the skew adjusting values for each respective LSU 111 K, 111 C, 111 M, 111 Y, for example, the rotation angles K, C, M, Y required for rotating the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, 138 Y of the respective skew adjusting parts 130 K, 130 C, 130 M, 130 Y.
  • the control part 201 controls the operations of the driving motor 121 and the clutch 151 according to the calculated rotation angles K, C, M, Y.
  • control part 201 calculates with software the rotation angles K, C, M, Y required for rotating the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, 138 Y of the respective skew adjusting parts 130 K, 130 C, 130 M, 130 Y on the basis of the first and second skew detection signals of the first and second skew detection sensors 211 , 212 , it is possible for a user to directly measure the rotation angles after a recording medium formed with an image is discharged out of the printer.
  • the user measures differences in skew.
  • skew values of other colors from an image of a predetermined pattern outputted onto a recording medium can be calculated using a microscope.
  • the rotation angles K, C, M, Y required for rotating the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, 138 Y of the respective skew adjusting parts 130 K, 130 C, 130 M, 130 Y to adjust the skews of the respective LSU 111 K, 111 C, 111 M, 111 Y and then inputs the calculated rotation angles K, C, M, Y of the respective LSU 111 K, 111 C, 111 M, 111 Y through an input part 202 of a control panel (not shown). If so, the control part 201 controls the operations of the driving motor 121 and the clutch 151 according to the inputted rotation angles K, C, M, Y
  • the inventive automatic skew adjusting apparatus 100 is applied to a wet type color electrophotographic printer having a transfer unit with a transfer belt 117 for transferring toner images formed on respective photoconductors, and a fixing unit for fixing toner images transferred to a recording medium
  • the present invention is not limited to this and can be applied to other types of printers.
  • the inventive automatic skew adjusting apparatus 100 can be applied to a printer (not shown) which employs a photoconductive belt (not shown) instead of a photoconductive drum as a photoconductor and includes a fixing unit (not shown) or a transfer/fixing unit (not shown) which directly transfers and fixes a toner image from the photoconductive belt to a recording medium without a transfer unit having a transfer belt 117 , with similar principles and constructions.
  • inventive automatic skew adjusting apparatus 100 can also be applied to a printer (not shown) which employs a photoconductive drum as a photoconductor and includes a fixing unit (not shown) or a transfer/fixing unit (not shown) which directly transfers and fixes an image formed on the photoconductive drum (not shown) to a recording medium without intervention of a transfer belt 117 .
  • a skew adjusting method for an image forming apparatus such as a wet type color electrophotographic printer comprising an automatic skew adjusting apparatus 100 configured is described below in detail with reference to FIGS. 4 through 10 .
  • each of the photoconductors for forming one of the four colors is charged with a layer of electric charge of a predetermined pattern such as a straight line corresponding to an image, for example, an electrostatic latent image, to be printed by a corresponding one of the respective black, cyan, magenta and yellow LSU 111 K, 111 C, 111 M, 111 Y.
  • liquid developer is deposited as a layer of developer with a high quantity of toner onto an area formed with the electrostatic latent image, and developed into toner images by a developing roller (not shown) of a developing unit (S 1 ).
  • the toner images each formed on a corresponding photoconductor by the developing unit are transferred to the transfer belt 117 by a first transfer roller (not shown) of a transfer unit and then moved to a second transfer roller by the transfer belt 117 .
  • the first and second skew detection sensors 211 , 212 detect each color toner image of the predetermined pattern transferred to the transfer belt, and output first and second skew detection signals for each color to the control part 201 .
  • the control part 201 compares outputting time points of the first and second signals for each color to calculate a skew value for each LSU on the basis of the difference between the outputting time points of the first and second skew detection signals (S 2 ).
  • the a skew adjusting value is calculated which may be adjusted through each skew adjusting part 130 K, 130 C, 130 M or 130 Y on the basis of the calculated skew value, that is, each of the rotation angles K, C, M, Y of the first, second, third and fourth adjusting gears 138 K, 138 C, 138 M, 138 Y (S 3 ).
  • the toner images moved to the second transfer roller are transferred to a medium P by the second transfer roller, fixed on the recording medium by a fixing roller (not shown) of a fixing unit, and then discharged out of the printer by a paper discharge roller of a paper discharge unit.
  • control part 201 After medium P is discharged out of the printer, the control part 201 reads out the positional information of the actuating part 140 previously stored in the memory 203 (S 4 ).
  • the control part 201 determines whether the position of the actuating part 140 read out from the memory 203 corresponds to that for a certain one of the respective LSU 111 K, 111 C, 111 M, 111 Y to be adjusted, for example. to a first position for actuating the skew adjusting part 130 K of the black LSU 111 K (S 5 ).
  • the first position is the position where the first worm gear 141 K of the actuating part 140 arranged on the driving shaft 123 of the driving motor 121 is engaged with the first adjusting gear 138 K of the skew adjusting part 130 K which adjusts the skew of the black LSU 111 K.
  • the control part 201 rotates the driving motor 121 clockwise or counterclockwise by a predetermined angle according to the calculated rotation angle K, while the clutch 151 is in OFF state, as shown in FIG. 9A .
  • the control part 201 judges whether any other LSU needs adjustment (S 7 ).
  • the control part 201 turns the clutch 151 of the positioning part 1500 N, so as to move the actuating part 140 provided on the driving shaft 123 to a second position as shown in FIG. 9B (S 8 ).
  • the second position is the position where the second worm gear 141 C of the actuating part is engaged with the second adjusting gear 138 C for adjusting the skew of the cyan LSU 111 C.
  • the photosensor 194 of the position detection part 193 provided at one side of the driving motor 121 generates and outputs high and low signals to the control part 201 due to the holes 195 a formed in the sensing hole part 195 provided on the sliding guide 180 .
  • the control part 201 counts the high signals of the photosensor 194 to calculate the moved position of the driving motor 121 and determines whether the present position of the actuating part 140 is the second position or not (S 10 ).
  • the control part 201 turns the clutch 151 OFF.
  • the clutch 151 is turned OFF, no electric current is applied to the clutch coil 155 and thus the magnetic force is lost.
  • the armature 159 is moved in the direction indicated by arrow B in FIG. 7 by the clutch spring 157 .
  • the driving clutch plate 152 separates from the driven clutch plate 153 and the power of the driving shaft 123 cannot be transmitted to the positioning shaft 175 (S 11 ).
  • the driving motor 121 rotates clockwise or counterclockwise by a predetermined angle according to the rotation angle C calculated for the cyan LSU 111 C.
  • the second worm gear 141 C formed on the driving shaft 123 also rotates, and the second adjusting gear 138 C of the skew adjusting part 130 C engages with the second worm gear 141 C for rotation by an angle corresponding to the rotation angle C of the cyan LSU 111 C (S 12 ).
  • control part 201 determines whether there is any LSU to be adjusted next (S 14 ).
  • the control part 201 moves the actuating part to a third position and then rotates the driving motor clockwise or counterclockwise by a predetermined angle according to the rotation angle C calculated for the magenta LSU 111 M in the same manner as above-mentioned steps S 8 -S 12 .
  • the third position is the position where the third worm gear 141 M of the actuating part 141 engages with the third adjusting gear 138 M for adjusting skew of the magenta LSU 111 M.
  • the control 201 determines again whether any LSU to be adjusted next is present or not (S 14 ).
  • the control part 201 moves the actuating part to a fourth position and then rotates the driving motor clockwise or counterclockwise by a predetermined angle according to the rotation angle Y calculated for the yellow LSU 111 Y in the same manner as above-mentioned steps S 8 -S 12 .
  • the fourth position is the position where the fourth worm gear 141 Y of the actuating part 141 engages with the fourth adjusting gear 138 Y for adjusting skew of the yellow LSU 111 Y.
  • the control part 201 determines again whether any LSU to be adjusted next is present or not (S 14 ).
  • control part 201 stores the present position of the actuating part 140 in the memory 203 and completes the adjusting operation, or returns again the position of the actuating part 140 to the first position by moving the driving motor 121 through the positioning part 170 , then stores the position of the actuating part 140 in the memory 203 and then completes the adjusting operation.
  • the exemplary embodiments of the present invention provide automatic adjustment for a skew of LSU body. Therefore, the time required for skew adjustment can be reduced and the degree of precision of skew adjustment can be relatively improved when compared to the manual skew adjustment.
  • the manufacturing costs can be reduced as compared to the case in which a separate motor is provided for each skew actuating part of an LSU, and the construction can be simplified because no large installation space and complicated wiring are needed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrophotography Configuration And Component (AREA)
  • Color Electrophotography (AREA)
US11/224,070 2004-09-24 2005-09-13 Automatic skew adjusting apparatus, image forming apparatus having the same and skew adjusting method thereof Abandoned US20060181009A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR2004-76893 2004-09-24
KR1020040076893A KR100574507B1 (ko) 2004-09-24 2004-09-24 자동 스큐조정장치, 그것을 갖는 화상형성장치 및 그스큐조정방법

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US (1) US20060181009A1 (fr)
EP (1) EP1641242A2 (fr)
KR (1) KR100574507B1 (fr)
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CN101893764B (zh) * 2010-07-12 2012-07-25 友达光电股份有限公司 立体显示器调整机构
CN108227181B (zh) * 2017-12-08 2020-06-16 华为技术有限公司 一种阵列转镜的光束扫描装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4396813A (en) * 1981-12-03 1983-08-02 Westinghouse Electric Corp. Enclosed circuit interrupter of the drawout type having a position actuated drive clutch on the drive means
US5052534A (en) * 1990-10-30 1991-10-01 Dana Corporation Electromagnetic synchronizing and shifting clutch
US6600504B2 (en) * 2000-09-11 2003-07-29 Konica Corporation Image forming apparatus having light beam adjusting mechanism
US6609777B2 (en) * 2001-06-06 2003-08-26 Seiko Epson Corporation Determination of recording position misalignment adjustment value in main scanning forward and reverse passes
US20050062832A1 (en) * 2003-09-18 2005-03-24 Fuji Xerox Co., Ltd. Image forming apparatus, drive mechanism of image forming apparatus and manufacturing method of a worm gear set

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4396813A (en) * 1981-12-03 1983-08-02 Westinghouse Electric Corp. Enclosed circuit interrupter of the drawout type having a position actuated drive clutch on the drive means
US5052534A (en) * 1990-10-30 1991-10-01 Dana Corporation Electromagnetic synchronizing and shifting clutch
US6600504B2 (en) * 2000-09-11 2003-07-29 Konica Corporation Image forming apparatus having light beam adjusting mechanism
US6609777B2 (en) * 2001-06-06 2003-08-26 Seiko Epson Corporation Determination of recording position misalignment adjustment value in main scanning forward and reverse passes
US20050062832A1 (en) * 2003-09-18 2005-03-24 Fuji Xerox Co., Ltd. Image forming apparatus, drive mechanism of image forming apparatus and manufacturing method of a worm gear set

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KR20060027957A (ko) 2006-03-29
KR100574507B1 (ko) 2006-04-27
CN1752858A (zh) 2006-03-29

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