Background technology
In general, laser printer is a kind of printing equipment, and this printing equipment, forms sub-image, and this sub-image is transferred to medium, on paper, to copy image to light-sensitive medium by the laser beam flying that will launch from laser diode on light-sensitive medium.Laser scan unit is a kind of device that forms image in laser printer, and this device produces laser beam and form image on light-sensitive medium.Figure 1A and 1B are a kind of synoptic diagram of conventional laser scanning element 10.Referring to Figure 1A and 1B, this conventional laser scanning element 10 comprises light source 11, collimation lens 12, aperture diaphragm 13, cylindrical lens 14, polygon mirror 15, scanning lens 16, catoptron 17 and photosensitive drums 18.Light source 11, collimation lens 12, aperture diaphragm 13, cylindrical lens 14, polygon mirror 15, scanning lens 16 and catoptron 17 place an independent casing 19, to prevent contaminations such as dust.
In this structure, the light beam of launching from light source 11 (as laser diode) is converted to the parallel beam that is parallel to optical axis by collimation lens 12.Parallel beam via hole diameter diaphragm 13 is shaped, and can gather in inferior direction of scanning by cylindrical lens 14 then, thus, forms a straight horizontal linear light with respect to inferior direction of scanning.Therefore, because the quick rotation of polygon mirror 15, this straight horizontal linear light in main scanning direction (just level was swept away the direction of paper) motion, and forms image through scanning lens 16 and catoptron 17 with at the uniform velocity on photosensitive drums 18.Scanning lens 16 has constant refractive index with respect to optical axis, and makes the light polarization on main scanning direction at the uniform velocity to reflect from the polygon mirror 15, thus, light is focused on the photosensitive drums 18.
In laser scan unit 10, the light beam by scanning lens 16 must along main scanning direction with rectilinear scanning on photosensitive drums 18.But because the distortion of the sum of errors of assembling, as shown in Figure 3, light beam can produce slight departing from inferior direction of scanning, and along main scanning direction, can not be on photosensitive drums 18 with rectilinear scanning.The crooked terminal A that refers to sweep trace (travel track of beam spot on the sensitization receiver just) is in different height X1 and the phenomenon of X2 with B.Bending refers to the bending of sweep trace (should be straight line).Crooked and crooked reduce the precision of printing, thereby reduced the quality of image.In the tandem laser scan unit in being used in color laser printer, crooked and bending especially is a problem.For example, in the color printer that uses the tandem laser scan unit, if the amount of bow that occurs on a plurality of photosensitive drums is not simultaneously, color restoration capability reduces greatly.Catoptron 17 compensates crooked and crooked by the mode of suitably regulating beam incident angle.
Fig. 2 is the traditional structure diagrammatic sketch of accommodation reflex mirror 17 degree of tilt.In this traditional structure, on frame, be provided with a groove 25, the bottom that makes catoptron 17 is obliquely in the insertion groove 25.Screw 22 is installed on the frame 19 position corresponding to catoptron 17 tops.The degree of depth that rotating screw 22 inserts with accommodation reflex mirror suitably 17, thereby the degree of tilt of accommodation reflex mirror 17.In addition, catoptron 17 usefulness planar springs 30 firmly fix, and these spring 30 usefulness screws 21 are fixed on the frame 19.
In general, be the compensated scanning distortion, the degree of tilt of accommodation reflex mirror changes the angle of beam flying on the photosensitive drums.Yet in order more effectively to compensate this distortion, corner that must the accommodation reflex mirror is to proofread and correct the angle of beam flying on the photosensitive drums.Simultaneously, also must regulate light beam and incide position on the scanning lens,, can compensate crooked and crooked thus effectively simultaneously with compensation incoming position error.Like this, only come the conventional art of compensated scanning distortion just can not satisfy the demands by accommodation reflex mirror corner.
Therefore, need a kind ofly can regulate the incident angle of scanning light beam and the new technology of position simultaneously.In addition, also need a kind of can be with the securing more firmly ancillary technique of catoptron.
Embodiment
Defined things is in order to help more fully to understand the embodiment of the invention in following explanation such as concrete structure and element.Therefore, the those of ordinary skill in this field can be done multiple change to described embodiment as can be seen under the situation that does not exceed scope of the present invention and spirit.In addition, for the purpose of simple and clear, clear, omit description to known 26S Proteasome Structure and Function.
The catoptron location structure of laser scan unit comprises that one keeps and the catoptron revolving part (Fig. 4 A to 4D), that rotates catoptron makes catoptron make the reflector position that straight line moves to change the retaining element (Fig. 5 A to 5D) that element (Fig. 5 A to 5D) and is fixed these two elements according to an embodiment of the invention.
Fig. 4 A to 4D illustrates the catoptron revolving part 110 of catoptron location structure according to an embodiment of the invention.Fig. 4 A, 4B, 4C and 4D are respectively front elevation, side view, rear view and the skeleton views of catoptron revolving part 110.Referring to Fig. 4 A to 4D, turning axle 112 stretches out from the front of catoptron revolving part 110.Be provided with the groove 115 of a catoptron that is used to insert at the back side of catoptron revolving part 110, to keep this catoptron.When catoptron revolving part 110 rotates around turning axle 112, insert the catoptron that catoptron inserts groove 115 and also rotate together, thus degree of tilt that can the accommodation reflex mirror.For being easy to rotate catoptron revolving part 110, being provided with one in the end of turning axle 112 and forming rectilinear groove 113.Therefore, when assembling, tool using can rotate catoptron revolving part 110 at an easy rate as screwdriver.Though in illustrated embodiment, groove 113 is straight lines, this groove also can be any suitable shape.On catoptron revolving part 110, be provided with a rotation stop hole 114 at least around turning axle 112.After having regulated the degree of tilt of catoptron, will rotate the retainer (not shown) and insert in the rotation stop hole 114, further rotate to prevent catoptron, to this, the back also will be described further.The next door that catoptron at catoptron revolving part 110 back sides inserts groove 115 is provided with many ribs 116, inserts groove 115 distortion to prevent catoptron.
Fig. 5 A to 5D illustrates according to an embodiment of the invention, and the reflector position of catoptron location structure changes element 120.Fig. 5 A, 5B, 5C and 5D are respectively front elevation, side view, rear view and the skeleton views that reflector position changes element 120.Referring to Fig. 5 A to 5D, the core that changes element 120 at reflector position is provided with an opening 121, and the turning axle 112 of catoptron revolving part 110 can pass through this opening.Therefore, catoptron revolving part 110 changes element 120 can be rotationally attached to reflector position.Below opening 121, be provided with a rotation retainer through hole 123.The rotation retainer passes rotation retainer through hole 123 and inserts in the rotation stop hole 114 of catoptron revolving part 110, makes catoptron revolving part 110 and reflector position change element 120 and is connected securely each other.Rotation retainer through hole 123 is microscler, makes catoptron revolving part 110 change element 120 with reflector position in predetermined angular range and links to each other.Around rotation retainer through hole 123, be provided with a groove 122, be convenient to install reliably the rotation retainer with predetermined depth.In addition, reflector position change element 120 front, opening 121 above be provided with a straight line and move stop hole 124.At least one side is provided with a straight line movement governor hole 125 on reflector position change element 120, and the straight line movement governor inserts wherein, also will further describe this back.
Fig. 6 A to 6D is the retaining element 130 of catoptron location structure according to an embodiment of the invention.Fig. 6 A, 6B and 6C are respectively front elevation, rear view and the skeleton views of retaining element 130.Fig. 6 D is the rear view of another kind of retaining element 130.Referring to Fig. 6 A to 6C, be provided with one at the back side of retaining element 130 and receive space 134, make reflector position change element 120 and can receive at this and do straight line in space 134 and move.Through hole 131,132 and 133 is set, and to move stop hole 124 corresponding with opening 121, rotation retainer through hole 123 and straight line that reflector position changes element 120 respectively for they.It is microscler moving stop hole 124 corresponding through holes 131 and 133 with opening 121 and straight line, and the straight line amount of movement that makes reflector position change element 120 can be regulated in predetermined scope.Similarly, also be microscler with rotating retainer through hole 123 corresponding through holes 132, catoptron revolving part 110 can be regulated in predetermined angular range.As shown in Figure 6A, with straight line move stop hole 124 corresponding through holes 133 around be provided with a groove 137 with predetermined depth can be in steady state (SS) so that the straight line after installing moves retainer (back will be described).The turning axle 112 of catoptron revolving part 110 passes through hole 131.
In addition, shown in Fig. 6 B and 6C, retaining element 130 has a straight line movement governor seat 135, so that the straight line movement governor stably is connected in the side that reflector position changes element 120.Straight line movement governor seat 135 has a groove 136 that receives the straight line movement governor.Groove 136 comprises that one has than major diameter with the major part 136a that receives straight line movement governor head and a smaller portions 136b with relative installation straight line movement governor main part than minor diameter.Rotate the straight line movement governor, in the reception space 134 of retaining element 130, move as straight line so that reflector position changes element 120.In order to rotate the straight line movement governor easily, be provided with an adjustment hole 138 in the side of retaining element 130 by peripheral operation.Retaining element 130 shown in Fig. 6 B and the 6C is provided with a straight line movement governor seat 135 in the one side.But, shown in Fig. 6 D, also can be provided with two straight line movement governor seats 135 of symmetry in retaining element 130 two relative sides.
Fig. 7 A and Fig. 7 B illustrate catoptron revolving part 110, reflector position changes the connection between element 120 and the retaining element 130.Referring to Fig. 7 A, reflector position changes element 120 and is contained in the reception space 134 of retaining element 130.Straight line movement governor 128 inserts the straight line movement governor hole 125 of reflector position change element 120 sides and is positioned in the groove 136 of straight line movement governor seat 135.Can be with a screw as straight line movement governor 128.The head of straight line movement governor 128 is exposed on the outside by adjustment hole 138.Instrument as screwdriver, can be inserted in the adjustment hole 138, to rotate straight line movement governor 128.At this moment, the turning axle 112 of catoptron revolving part 110 passes reflector position and changes the opening 121 of element 120 and the through hole 131 of retaining element 130, makes that catoptron revolving part 110 changes element 120 with reflector position and retaining element 130 links to each other.Retaining element 130 can be attached on the outer frame (not shown) of laser scan unit.Fig. 7 B illustrates catoptron revolving part 110, reflector position changes element 120 and retaining element 130 interconnective states.
Fig. 8 A and 8B are respectively that catoptron revolving part 110 and reflector position change connection and the operation between the element 120.Referring to Fig. 8 A, the turning axle 112 of catoptron revolving part 110 inserts in the opening 121 of reflector position change element 120, makes catoptron revolving part 110 rotatably change element 120 with reflector position and links to each other.Rotation retainer 127 passes through rotation retainer through hole 123, and inserts loosely in the rotation stop hole 114 of catoptron revolving part 110.Can be with a screw as rotation retainer 127.Fig. 8 B is the front elevation of assembly shown in Fig. 8 A.Use an instrument, screwdriver for example rotates the degree of tilt that turning axle 112 can the accommodation reflex mirror.When turning axle 112 rotated, the rotation retainer 127 of Cha Ruing moved in rotation retainer through hole 123 (they have microscler shape) loosely.After the degree of tilt of having determined catoptron, rotate rotation retainer 127 and also fixed, reflector position change element 120 and catoptron revolving part 110 are firmly fixed each other.Like this, can prevent to change the degree of tilt of catoptron.
The straight line that Fig. 9 A to 9D shows reflector position change element 120 moves.For describing clearly, the catoptron revolving part 110 that links to each other with reflector position change element 120 is not shown in the drawings.Referring to Fig. 9 A, this figure is a rear view, and when straight line movement governor 128 deeply inserted reflector position change element 120, reflector position changed the left side that element 120 is positioned at the reception space 134 of retaining element 130.Fig. 9 B is the front elevation of the position when reflector position changes element 120 and retaining element 130 and is connected with each other shown in Fig. 9 A.Referring to Fig. 9 B, when straight line movement governor 128 deeply inserted in the reflector position change element 120, the straight line that reflector position changes element 120 moved the right side that stop hole 124 is positioned at the through hole 133 of retaining element 130.Similarly, from the front, the opening 121 of reflector position change element 120 is positioned at the right side of the through hole 131 of retaining element 130.
Position for accommodation reflex mirror position change element 120, instrument as screwdriver, can be inserted adjustment hole 138 and rotation screw cutter, thereby rotate straight line movement governor 128, make straight line movement governor 128 change element 120 and be in released state with respect to reflector position.At this moment, because straight line movement governor 128 is to be fixed in the straight line movement governor seat 135 of retaining element 130, so shown in Fig. 9 C, see from behind, reflector position changes element 120 and moves to the right side that receives space 134.Fig. 9 D is the front elevation of the position when reflector position being shown changing element 120 and retaining element 130 and interconnect shown in Fig. 9 C.Referring to Fig. 9 D, when straight line movement governor 128 was in the state that unclamps with respect to reflector position change element 120, the straight line that reflector position changes element 120 moved the left side that stop hole 124 is shifted to the through hole 133 of retaining element 130.Similarly, from the front, the opening 121 of reflector position change element 120 is also shifted to the left side of the through hole 131 of retaining element 130.After the position of reflector position change element 120 is determined by above-mentioned operation, straight line is moved retainer 129 (seeing Figure 10 C) insertion straight line move stop hole 124 and fastening, like this, reflector position change element 120 is connected and is fixed on the retaining element 130.
Figure 10 A to 10C illustrates the skeleton view of the operation of catoptron location structure according to an embodiment of the invention.Referring to Figure 10 A, rotate the turning axle 112 of the catoptron revolving part 110 that stretches out from retaining element 130, to regulate the degree of tilt of the catoptron 140 that links to each other with catoptron revolving part 110.After the degree of tilt of catoptron 140 is determined, with instrument,, also rotate in the through hole 132 of insertion retaining element 130, thereby fixing rotation retainer 127 is securely fixed on the reflector position change element 120 catoptron revolving part 110 as screwdriver.
Afterwards,,,, insert the adjustment hole 138 and the rotation that are arranged on retaining element 130 1 sides as screwdriver with an instrument referring to Figure 10 B, with rotation straight line movement governor 128, thus the position of accommodation reflex mirror position change element 120.When reflector position change element cup 120 moved, the catoptron 140 that links to each other with catoptron revolving part 110 also moved.Referring to Figure 10 C, when the position of catoptron 140 is determined by this operation, straight line moves retainer 129 and is inserted into the through hole 133 of retaining element 130 and enters straight line and move in the stop hole 124, and like this, reflector position changes element 120 and is securely fixed on the retaining element 130.Here, to move retainer 129 can be a screw to straight line.
In catoptron location structure according to the abovementioned embodiments of the present invention, make catoptron 140 can be relatively with respect to the rack inclining location difficulty.In other words, when catoptron 140 during with respect to rack inclining, reflector position changes element 120 and retaining element 130 all is not parallel to frame.Therefore, when pressure is located catoptron 140 with respect to rack inclining, whole assembly instability.In addition, catoptron 140 and frame may gross distortions.
Be the description to other exemplary embodiment of catoptron location structure of the present invention below, this embodiment can overcome above-mentioned problem.
Figure 11 illustrates the catoptron keeper 210 of catoptron location structure according to an embodiment of the invention.In Figure 11, show front elevation, side view and the rear view of this keeper from left to right successively.Turning axle 212 vertically stretches out from the front of catoptron keeper 210.Be provided with a catoptron at the back side of catoptron keeper 210 and insert groove 211, be used for fixing insertion catoptron (not shown) wherein.When catoptron keeper 210 when turning axle 212 rotates, insert the catoptron that catoptron inserts groove 211 and also rotate, therefore, degree of tilt that can the accommodation reflex mirror.Be provided with an arch section 213 with predetermined curved convergent in the end of turning axle 212.Arch section can be a semisphere or conical.Stretch out the diameter cylindrical bar 214 littler from arch section 213 than turning axle 212.When the anglec of rotation of accommodation reflex mirror and straight line amount of movement, can come rotating mirror retaining member 210 or change the position by holding and operate cylindrical bar 214.
Thereby rotate catoptron keeper 210 or change its position by supporting and operate cylindrical bar 214.
Figure 12 illustrates the reflector position fixture 220 of catoptron location structure according to an embodiment of the invention.In Figure 12, the centre is a front elevation, is vertical view below, the right be side view.Be provided with an opening 221 at the middle part of reflector position fixture 220, this opening matches with the arch section 213 of the turning axle 212 of catoptron keeper 210.The internal diameter of opening 221 is curved identical with arch section 213, and opening 221 is accurately cooperated with the arch section 213 that is arranged on turning axle 212 ends.Be provided with locking hole 222 near each angle of reflector position fixture 220, the locking member (not shown) inserts in this locking hole, be used for reflector position fixture 220 is fixed to, for example, on the outer frame 240 (seeing Figure 13) of laser scan unit.Locking hole 222 is microscler, makes the straight line amount of movement of reflector position fixture 220 to regulate in predetermined scope.
Figure 13 illustrates the catoptron location structure that assembles according to an embodiment of the invention.The catoptron keeper 210 that supports and rotate catoptron is located in the laser scan unit.The turning axle 212 of catoptron keeper 210 passes the hole 245 on the frame 240 and stretches out from frame 240.As mentioned above, there is an arch section 213 end of turning axle 212.Cylindrical bar 214 stretches out from the center of arch section 213, makes to rotate catoptron keeper 210 in the axial direction and it is moved along the direction that is parallel to frame 240 with manual or automatic mode.The hole 245 of frame 240 is provided with microscler spigot surface, makes the straight line amount of movement of catoptron keeper 210 to regulate in predetermined scope.In other words, the width in hole 245 is identical with the diameter of turning axle 212, and the length in hole 245 equals catoptron keeper 210 in the displacement of length direction, the diameter and the related error sum of turning axle 212 inclinations of turning axle 212.
In this case, by rotating catoptron keeper 210 vertically, it being moved in the direction that is parallel to frame 242, then with the stationkeeping of catoptron keeper 210, crooked and bending is compensated.For stationary mirror keeper 210, the outside that reflector position fixture 220 is arranged at frame makes it closely contact with catoptron keeper 210, thereby reflector position fixture 220 is fixed on the frame 240.Be arranged near the locking hole 222 reflector position fixture 220 each angle and be arranged on locking hole 242 on the frame 240 by the locking member (not shown) is inserted, reflector position fixture 220 is fixed in frame 240.At this moment, the cylindrical bar 214 of catoptron keeper 210 passes the opening 221 of reflector position fixture 220, and the arch section 213 of catoptron keeper 210 matches with the internal diameter 223 of opening 221.It is identical curved that the internal diameter 223 of opening 221 and arch section 213 have, so they each other accurately and closely contact.
Because catoptron keeper 210 is curved identical with reflector position fixture 220 surfaces, even so rotate with parallel moving process in, catoptron keeper 210 tilts with respect to frame 240, reflector position fixture 220 still secured in parallel on frame 240.Therefore, catoptron keeper 210 and reflector position fixture 220 can stably be fixed on frame 240, and crooked and bending simultaneously is compensated.After and bending crooked in compensation, reduce relative position between catoptron keeper 210 and the reflector position fixture 220 owing to the influence that is subjected to impulsive force etc. changes, man-hour can added, when molded, the surfaceness of the arch section 213 of accommodation reflex mirror keeper 210 and the internal diameter 223 of reflector position fixture 220.Perhaps, can carry out surface treatment, on the surface of arch section 213 and internal diameter 223, to form a nonskid coating.
Figure 14 A to 14C illustrates the operation according to another embodiment of the present invention catoptron location structure.After the relative end of two catoptron keepers 210 and catoptron 140 linked to each other, catoptron keeper 210 inserted in the frames 240.Afterwards, two reflector position fixtures 220 are installed on the catoptron keeper 210.Rotation or move the amount that two or one of them catoptron keeper 210 move with the corner and the straight line of accommodation reflex mirror 140.Behind the corner of having regulated catoptron 140 and straight line amount of movement, reflector position fixture 220 is fixed on the frame 240.At this moment, catoptron 140 can be located such that as the axis of catoptron 140 as shown in Figure 14 A aim at datum line, as shown in Figure 14B catoptron 140 axis parallel offset datum line or shown in Figure 14 C the axis of catoptron 140 tilt with respect to datum line.The parallel offset datum line is also fixing as shown in Figure 14B when catoptron 140, then moves the reflector position fixture 220 that is positioned at opposite side along equidirectional, and is fixed on the frame 240.When catoptron 140 tilts with respect to datum line shown in Figure 14 C, move the reflector position fixture 220 that is positioned at opposite side in opposite direction, and be fixed on the frame 240.Under any situation of change catoptron 140 positions shown in Figure 14 B and 14C, because catoptron keeper 210 has identical curved surface respectively with reflector position fixture 220, so compensating under the crooked and crooked situation, catoptron keeper 210 and reflector position fixture 220 can stably be fixed on the frame 240.
If be difficult in frame 240, accurately cast out the spigot surface that is provided with into catoptron keeper 210, can produce a reflector position guide 230 as shown in figure 15 separately, then itself and frame 240 are fitted together.Referring to Figure 15, reflector position guide 230 has an opening 232, and the turning axle 212 of catoptron keeper 210 passes this opening and is being directed on its one side.The opening 232 of reflector position guide 230 has a microscler spigot surface, thus can be in predetermined scope the straight line amount of movement of accommodation reflex mirror keeper 210.In detail, the width of opening 232 is identical with the diameter of turning axle 212, and the length of opening 232 equals distance, the diameter of turning axle 212 and the deviation sum that turning axle 212 tilts to be produced that catoptron keeper 210 moves at length direction.Each side at the opposite side of opening 232 is provided with locking hole 233, is used for reflector position guide 230 is fixed in frame 240.
Figure 16 illustrates the catoptron location structure assembly that comprises reflector position guide 230.Reflector position guide 230 inserts in the frame 240 between catoptron keepers 210 and the reflector position fixture 220 and is fixed thereon.The turning axle 212 of catoptron keeper 210 passes the opening 232 on the reflector position guide 230 and stretches out from frame 240.In this case, by axial rotation and parallel mobile mirror keeper 210 compensating for tilt and bending, with reflector position fixture 220 catoptron keeper 210 is fixed on the position that has compensated then.In other words, except reflector position guide 230 be provided with separately rather than directly be formed at spigot surface in the frame 240, assembly shown in Figure 16 is identical with assembly shown in Figure 13.
Figure 17 A to 17C illustrates the operation of the catoptron location structure that comprises reflector position guide 230.Though increased reflector position guide 230, the operation of the catoptron location structure shown in Figure 17 A to 17C is with identical shown in Figure 14 A to Figure 14 C.In other words, catoptron 140 can be located such that as the axis of catoptron 140 as shown in Figure 17 A aim at fully with datum line, shown in Figure 17 B catoptron 140 axis parallel offset datum line or shown in Figure 17 C the axis of catoptron 140 tilt with respect to datum line.When catoptron 140 is fixed in the situation of parallel offset datum line, move the reflector position fixture 220 that is positioned at opposite side along equidirectional, and be fixed on the frame 240.When catoptron 140 tilts with respect to datum line, move the reflector position fixture 220 that is positioned at opposite side in opposite direction, and be fixed on the frame 240.Under any situation that changes catoptron 140 positions, because catoptron keeper 210 has identical curved surface respectively with reflector position fixture 220, so compensating under the crooked and crooked situation, catoptron keeper 210 and reflector position fixture 220 can stably be fixed on the frame 240.
Now the crooked and crooked operation of catoptron location structure compensation of using above-mentioned any one embodiment of the present invention in laser scan unit is described.As mentioned above, because assembly error and distortion produce when making the light beam offset slightly crooked and crooked.In the present invention, so crooked and crooked by the corner and the position of accommodation reflex mirror are compensated independently.
Figure 18 A illustrates the situation of catoptron location structure between polygon mirror 150 and scanning lens 160 according to an embodiment of the invention.In this situation, catoptron 140 is between polygon mirror 150 and scanning lens 160.Regulate by rotating mirror 140 suitably through the angle that the light beam of polygon mirror 150 deviations incides on the scanning lens 160.In addition, when light beam does not incide the center section of scanning lens 160 exactly, can use the position of catoptron location structure change catoptron 140, thereby the adjusting light beam incides the position on the scanning lens 160.
Figure 18 B illustrates according to an embodiment of the invention the catoptron location structure and is positioned at scanning lens 160 and is scanned face, as photosensitive drums 170, between the time situation.In this situation, catoptron 140 is between scanning lens 160 and photosensitive drums 170.At this moment, the angle of catoptron and position can use the catoptron location structure suitably to regulate, and make via scanning lens 160 and focus on light beam on the photosensitive drums 170 so that position and angle project on the photosensitive drums 170 accurately.Therefore, in scanning process, can compensate crooked and crooked.
As mentioned above, according to the present invention, the angle of catoptron and position can be regulated to compensate crooked and crooked at an easy rate, independently.Therefore, the present invention has mechanically overcome the crooked and crooked difficulty that compensates that causes owing to the alignment error of laser beam in the tandem laser scan unit of for example color printer.
Although show and described the present invention by some embodiments of the present invention, but will be understood by those skilled in the art that, under the situation that does not exceed the determined scope and spirit essence of the present invention of claims, multiple change can made aspect form and the details to the present invention.
The application requires to enjoy in the 10-2004-0082077 that submits to Korea S Department of Intellectual Property on October 14th, 2004 and on October 19th, 2004 and the right of priority of 10-2004-0083585 korean patent application, and its whole disclosure is incorporated into this by reference.