JP5266536B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: in the case of a conventional adjusting mechanism performing fine adjustment of an angle or a position of an exposure device using a laser as a light source, the mechanism and adjustment operation are complicated, and not only it takes time for adjustment but also accuracy of adjustment is not good. <P>SOLUTION: In an image forming apparatus, an exposure device 30 having a laser light source and a scanning optical system deflecting light from the laser light source and emitting a scanning light beam is supported by at least first, second and third supporting points T1, T2 and T3, and a first adjusting means adjusting inclination of a main-scanning direction of the scanning light beam is provided at a first supporting part provided with the first supporting point, to make it possible to adjust the inclination in the main-scanning direction by only the adjustment of the first adjusting means, and a sphere bearing supporting the exposure device rotatably in the entire directions is provided at the first supporting part. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus that scans and exposes a photosensitive member with a light beam to form an image.

  (1) In an image forming apparatus that scans and exposes a photoconductor using a light beam to form an image, the accuracy of the position at which the light beam is incident on the photoconductor affects the image quality. An exposure apparatus is configured to enter the body.

  Particularly, in a color image forming apparatus that forms a color image by performing a plurality of exposures to form a plurality of images and superimposing the plurality of images, it is required to maintain the position with high accuracy. The

  A typical exposure apparatus that performs scanning exposure with a light beam is an exposure apparatus using a laser. Regarding the adjustment of the position in the laser exposure apparatus, for example, in Japanese Patent No. 2570176, a laser light source and a scanning exposure optical system are used. An adjustment mechanism is disclosed that adjusts the position and angle of an exposure apparatus that includes the XYZ direction with respect to the XYZ directions. This adjustment mechanism adjusts the incident position of the light beam on the photosensitive member by adjusting the X, Y, and Z directions at the two ends of the side of the rectangular exposure apparatus.

  (2) Many color image forming apparatuses include a plurality of exposure apparatuses that form a multi-color image, and these exposure apparatuses are provided in the image forming apparatus with high positional accuracy. In particular, the relative position between the exposure apparatuses must be high. If the position accuracy between the exposure apparatuses is not good, a position shift occurs between the color images, a color shift occurs, and the image quality deteriorates. The positional relationship between the exposure apparatuses needs to be maintained throughout the operation period of the image forming apparatus.

  In order to satisfy such a condition regarding the position of the exposure apparatus, in a conventional color image forming apparatus, a plurality of exposure apparatuses are connected to each other with an adhesive such as an ultraviolet adhesive.

  (1) In the adjustment mechanism disclosed in the patent publication, a total of six adjustment means are provided in order to perform adjustment at two points in each direction of XYZ. This complicates the adjustment. Moreover, in the prior art, a specific adjustment mechanism that can achieve a simple configuration and high adjustment accuracy has not been disclosed.

  (2) The fixing means for fixing the exposure apparatuses with an adhesive requires a great amount of bonding time to secure a desired strength, which is a problem in manufacturing.

  An object of the present invention is to solve the above-described problems in a conventional image forming apparatus using a light beam.

  The object of the present invention is achieved by the following invention.

1. An exposure apparatus having a laser light source and a scanning optical system that deflects light from the laser light source and emits a scanning light beam is supported by at least a first fulcrum, a second fulcrum, and a third fulcrum, and the first fulcrum and the first fulcrum Two fulcrums are provided at both ends of the optical path formed by the scanning optical system, and the first fulcrum and the second fulcrum are provided at symmetrical positions across the optical axis of the scanning optical system, and the third fulcrum Is a fixed point provided in a plane perpendicular to the scanning plane that includes the optical axis of the scanning optical system, and the exposure apparatus is rotated in all directions on the first support portion provided with the first fulcrum. Provided is a spherical bearing that can be supported, and the movement of the first fulcrum is performed by using a straight line connecting the other two fulcrums as a rotation axis, and at least one of the other two fulcrums is the movement of the first support. It is movable in a direction substantially perpendicular to the direction and drives the first support part Constituted by engaging piece for engaging the di and said drive screw, said drive screw, the drive source for driving the engaging piece and the driving screw, the main scanning direction of the scanning light beam to the first support portion image forming apparatus inclination constitutes a first adjusting means for adjusting the, characterized in that to allow only by adjustment of the first adjusting means to perform the adjustment of the main scanning direction of the inclination of the.

2. The image forming apparatus according to 1, wherein Rukoto which have a spacing prevention member for preventing the separation of spheres the sphere bearing support.

3. 3. The image forming apparatus according to 2 , wherein the separation preventing member has elasticity .

4). Together with the spherical body bearing supporting the spherical at three points, according to claim 2 or the 3 the separation preventing member is characterized Rukoto is pressed against the spherical body in contact with at least one point on said spherical bearing to the sphere The image forming apparatus described in 1.

5. 2 or 3 above , wherein the spherical bearing supports the spherical body in an annular shape, and the separation preventing member contacts the spherical body at at least one point to press the spherical body against the spherical bearing. The image forming apparatus described in 1.

6). 2. The image forming apparatus according to item 1 , wherein the engagement piece is composed of two sheets that engage with the drive screw from opposite directions .

7). 7. The image forming apparatus according to claim 6 , wherein the two engagement pieces are formed as projecting portions extending from one common base portion .

8). 8. The image forming apparatus according to 6 or 7, wherein the two engagement pieces are engaged with the drive screw at a position shifted from each other by approximately ½ of the pitch of the drive screw. .

9. 2. The image forming apparatus according to 1 , wherein the image forming apparatus includes a plurality of the exposure apparatuses, and each of the plurality of exposure apparatuses includes the first adjustment unit .

10. Wherein the first adjusting means image forming apparatus according to 1, wherein Rukoto to have a driving source comprising the motor.

11. 2. The image forming apparatus according to 1 , wherein the first adjustment unit includes a drive source including a laminated piezoelectric actuator .

12 The second indicator provided with the second fulcrum is provided with second adjusting means for adjusting variation in magnification in the main scanning direction of the scanning light beam, and the variation in magnification is only adjusted by the second adjusting means. the image forming apparatus according to any one of claims 1 to 11, characterized in that made it possible to make adjustments.

According to the inventions of claims 1 and 6 to 8 , it is possible to adjust the inclination in the main scanning direction with high accuracy by a simple support structure and a simple adjustment operation, and easily and accurately with a small number of adjustments. The scanning optical system can be adjusted, and a high-quality image forming apparatus is realized. In addition, since the adjustment is performed about the optical axis of the scanning optical system, the adjustment amount is small and a more precise adjustment is possible. In addition, when assembling various members such as a drive screw, an engagement piece, and an engagement block constituting the adjustment means, a high-precision adjustment means is realized without requiring a high degree of assembly accuracy.

According to the invention of any one of claims 2 to 5 , as a spherical bearing that supports the exposure apparatus so as to be rotatable in all directions, a support structure with extremely little positional deviation accompanying rotation is realized, and adjustment with high accuracy is possible. The adjustment value is maintained over a long period of time.

According to the invention of claim 9 , a color image forming apparatus with high image quality is realized.

According to the invention of any one of claims 9 to 10 , adjustment with extremely high accuracy can be performed.

According to the eleventh aspect of the present invention, it is possible to adjust the variation in magnification in the main scanning direction with high accuracy by simple adjustment means.

1 is a diagram illustrating an entire image forming apparatus according to Embodiment 1 of the present invention. 1 is a top sectional view of an exposure apparatus of an image forming apparatus according to Embodiment 1 of the present invention. It is a figure which shows the 1st, 2nd support part of exposure apparatus. It is a figure which shows the 3rd support part of exposure apparatus. FIG. 6 is a top cross-sectional view of an exposure apparatus of an image forming apparatus according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view taken along line AX-BX-CX in FIG. 5. It is a figure which shows the support part of exposure apparatus. It is a figure which shows the support part of exposure apparatus. It is a figure which shows the support part of exposure apparatus. It is a figure which shows the specific example of the support structure of the frame in a 3rd fulcrum. It is a figure which shows the example of a 2nd adjustment means. It is a figure which shows the support part of the exposure apparatus of the image forming apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows the support part of the exposure apparatus of the image forming apparatus which concerns on Embodiment 4 of this invention. It is a figure which shows the whole image forming apparatus which concerns on Embodiment 5 of this invention. It is a perspective view which shows the coupling | bonding structure between the exposure apparatuses of Embodiment 5 of this invention. It is a disassembled perspective view of exposure apparatus. It is a figure which shows the coupling | bonding process between exposure apparatuses. It is a figure which shows an example of the coupling | bond part between exposure apparatuses. It is a figure which shows the other example of the coupling | bond part between exposure apparatuses. It is a figure for demonstrating the adjustment of the position between exposure apparatuses.

(1) Embodiment 1
A first embodiment of the present invention will be described with reference to FIGS. 1 is a diagram showing the entire image forming apparatus according to the first embodiment, FIG. 2 is a top sectional view of the exposure apparatus of the image forming apparatus according to the first embodiment, and FIG. 3 is a first view of the exposure apparatus of FIG. It is a figure which shows a support part and a 2nd support part.

  A belt-like photosensitive member 1 having an organic photoconductive layer formed on a conductive substrate is stretched between a driving roller 11 and driven rollers 12 and 13 with an appropriate tension by a tension roller 14, and is rotated as indicated by an arrow. To do. Around the photoreceptor 1, an image forming unit that forms yellow, magenta, cyan, and black images by charging, exposure, and development is disposed. The image forming unit for a yellow image includes a charging device 2Y composed of a scorotron charger, an exposure device 30Y having a scanning optical system using a semiconductor laser as a light source, and a developing sleeve 41, and a developing device 4Y for performing reversal development. Similarly, the magenta image forming unit includes the charging device 2M, the exposure device 30M, and the developing device 4M, the cyan image forming unit includes the charging device 2C, the exposure device 30C, and the developing device 4C, and the black image forming unit includes the charging device 2K. It comprises an exposure device 30K and a developing device 4K.

  A bias voltage having the same polarity as the electrostatic latent image on the photoreceptor 1 is applied to the developing sleeves 41 of the developing devices 4Y, 4M, 4C, and 4K, and these developing devices perform development by a non-contact / reverse developing method. A toner image is formed on the photoreceptor 1. The developing devices 4Y, 4M, 4C, and 4K are supplied with toner of each color from the respective toner containers 5Y, 5M, 5C, and 5M.

  A charging device 2F, a transfer device 7 including a transfer roller to which a transfer voltage is applied, and a cleaning device 8 are further arranged opposite to the photoconductor 1.

  Paper feed cassettes 20A and 20B for storing recording paper P for forming an image and a manual paper feed tray 20C are provided at the lower and side portions of the image forming apparatus, and are respectively provided by paper feed units 21A, 21B and 21C. The recording paper P is sent out toward the transfer device 7. A registration roller 23 conveys the recording paper P to the transfer device 7 in synchronism with image formation on the photosensitive member 1. Reference numeral 24 denotes a fixing device having a heating roller and a pressure roller; 25A, 25B, and 25C, transport rollers for transporting the recording paper P; and 26, a paper discharge tray on which the discharged recording paper P is deposited.

  In image formation, the photoreceptor 1 rotates as indicated by an arrow, and the yellow image forming unit, magenta image forming unit, cyan image forming unit, and black image forming unit are controlled in accordance with the rotation of the photoreceptor 1. At this timing, a toner image of each color is formed on the photoreceptor 1 by charging, exposure, and development, and a full-color toner in which the toner images of each color are overlapped is formed on the photoreceptor 1. The potential of the formed full-color toner image is adjusted by the charging device 2F.

  In synchronism with the formation of the full-color toner image on the photosensitive member 1, the recording paper P is conveyed from the registration roller 23 and is in close contact with the photosensitive member 1 in the transfer device 7. The full color toner image on the body 1 is transferred to the recording paper P.

  The full color toner image transferred to the recording paper P is fixed by the fixing device 24, and a full color image is formed on the recording paper P. The recording paper P that has passed through the fixing device 24 is transported by transport rollers 25A, 25B, and 25C and is discharged to a paper discharge tray 26. The photoreceptor 1 that has passed through the transfer position has the residual toner removed by the cleaning device 8 and the surface state is made uniform by the charge removal by the charge removal lamp 9.

  The exposure apparatuses 30Y, 30M, 30C, and 30K in the present embodiment perform scanning exposure by scanning in the main scanning direction of the laser beam and scanning in the sub-scanning direction by moving the photosensitive member 1, and electrostatic latent images are formed on the photosensitive member 1. Although an image is formed, each exposure apparatus incorporates a scanning exposure adjusting mechanism. The adjusting mechanism adjusts the variation in magnification in the main scanning direction, that is, adjusts the horizontal magnification and the inclination in the main scanning direction.

  The following description is an explanation of an adjustment mechanism used in common for the exposure apparatuses 30M, 30C, and 30K, and these exposure apparatuses will be described as the exposure apparatus 30. Note that the exposure mechanism 30Y, 30M, 30C, and 30K do not need to be provided with the adjustment mechanism, and any one exposure apparatus is not provided with the adjustment function, and is based on an exposure apparatus that does not have the adjustment mechanism. As another example, at least one of adjustment of inclination in the main scanning direction and adjustment of magnification variation in the main scanning direction of another exposure apparatus may be performed.

  The exposure apparatus 30 includes a laser light source including a semiconductor laser 35 and a scanning optical system including a first cylindrical lens 37, a polygon mirror unit 31, an fθ lens 32, and a second cylindrical lens 33. These laser light source and scanning optical system are fixed to a box-shaped frame 307. The light beam from the semiconductor laser 35 is deflected by the high-speed rotating polygon of the polygon mirror unit 31 and is scanned and exposed at high speed in the main scanning direction as indicated by the arrow W.

  The frame 307 is supported by a support plate 301 fixed to the image forming apparatus main body at intersections T1, T2, and T3 of alternate long and short dash lines AA, BB, and CC that form a triangle. Thus, the exposure apparatus 30 is supported by the image forming apparatus main body at the first fulcrum T1, the second fulcrum T2, and the third fulcrum T3.

  The structure of the first support portion of the frame 307 at the first fulcrum is as shown in FIG.

  The coupling member 302 coupled by the screw portion 302b is fixed to the foot portion 304 of the frame body 307. The coupling member 302 has a screw portion 302b and a sphere 302a, and the sphere 302a is supported by a sphere bearing 303 so as to be rotatable in all directions including up, down, left and right. The coupling member 302 and the spherical bearing 303 constitute a first support portion. The spherical bearing 303 is guided by an intermediate member 305 so as to be movable up and down as indicated by an arrow X by a guide portion 301 a provided on the support plate 301. The intermediate member 305 is driven up and down by an eccentric cam 306 driven and rotated by the motor M1.

  The motor M1 and the eccentric cam 306 constitute first adjusting means for adjusting the inclination of the light beam in the main scanning direction. As the first adjusting means, other driving means such as a laminated piezoelectric actuator can be used instead of the motor M1 and the eccentric cam.

  By driving the motor M1, the frame body 307 moves up and down in the direction of the arrow X, and by this up and down movement, the exposure apparatus 30 rotates about the alternate long and short dash line BB, so the angle in the main scanning direction indicated by W changes. The inclination in the main scanning direction is adjusted.

  The structure of the second support portion of the frame 307 at the second fulcrum T2 is as shown in FIGS.

  A coupling member 316 is supported by a pair of rising portions 317 provided on the frame body 307. The coupling member 316 is integrally formed with the rising portion 317. A rod-shaped coupling member 316 shown in FIG. 3C penetrates a round hole provided in the rising portion 317. The coupling member 316 is provided with a partial sphere 314a that can slide on the coupling member 316 in the arrow Z direction. The partial sphere 314a is supported by a sphere bearing 314 so as to be rotatable in all directions. The spherical bearing 314 is held by an intermediate member 315, and the intermediate member 315 is guided by the holding portion 321 so as to be slidable in the arrow Y direction. The holding part 321 is fixed to the support plate 301. The intermediate member 315 is driven left and right by an eccentric cam 322 that is driven and rotated by the motor M2.

  The motor M2 and the eccentric cam 317 constitute second adjusting means for adjusting variation in magnification of the light beam in the main scanning direction. As the second adjusting means, other driving means such as a laminated piezoelectric actuator can be used instead of the motor M2 and the eccentric cam.

  By driving the motor M2, the frame body 307 moves left and right in the direction of the arrow Y, and by this left and right movement, the exposure apparatus 30 rotates about the first fulcrum, so that the reflection point of the polygon mirror unit 31 moves from the reflection point to the surface to be scanned. The reaching optical path length varies in different manners at each position on the scanning line, and the variation in magnification in the main scanning direction is adjusted.

  The structure of the third support portion of the frame 307 at the third fulcrum T3 is as shown in FIG.

  A coupling member 309 is supported on a pair of rising portions 308 provided on the frame body 307. The coupling member 309 penetrates into a long hole 310 provided in the rising portion 308, and is movable in the direction of arrow Y in FIG. The coupling member 309 is provided with a partial sphere 312a that can slide on the coupling member 309 in the arrow Z direction. The partial sphere 312a is supported by a sphere bearing 312 so as to be rotatable in all directions.

  With such a support structure of the frame body 307, the frame body 307 can move in directions perpendicular to the Y and Z directions at the third fulcrum T3, and this movement is a rotational motion around the first fulcrum T1. .

  The frame 307 moves up and down at the first fulcrum and rotates around the alternate long and short dash line B by the rotational drive of the motor M1. By this rotation, the inclination of the scanning line on the surface to be scanned is adjusted. In the adjustment, for example, a pattern parallel to the main scanning direction is written by a plurality of scanning optical devices to form an image, and the frame body 307 is adjusted so that the inclination error of the formed line image is eliminated between the exposure devices. This is performed by moving in the X direction (FIG. 3A).

  The frame 307 rotates around the first fulcrum by the rotational drive of the motor M2. By this rotation, the optical path length difference from the reflection point of the polygon mirror unit 31 to the surface to be scanned is adjusted, and the optical path length at each image height is optimized, so that variation in magnification in the main scanning direction, that is, main scanning is performed. The difference in magnification at both ends of the direction is adjusted. This adjustment is performed by measuring variation in lateral magnification, that is, non-uniformity in magnification in the main scanning direction, from an image formed by scanning exposure.

  Further, the variation in partial magnification in the main scanning direction can be detected by measuring at least three or more images formed by performing scanning exposure in each exposure apparatus. For example, a line perpendicular to the optical scanning direction at both ends and the center of the image is formed by each exposure apparatus, and the position error in the main scanning direction of the line image created by each exposure apparatus at each measurement point is detected, thereby scanning region It becomes possible to detect the difference in magnification between the upstream and downstream of the scanning line with the whole magnification and the optical axis center as a boundary. Furthermore, as shown in FIG. 20, an image position detection pattern in the shape of a letter “F”, which is not a line perpendicular to the optical scanning direction but a line parallel to the main scanning direction and a line inclined by about 45 °. When ML, MC, and MR are created, the position of the exposure apparatus can be detected at low cost by using the LED 503 and the light receiving element 504 instead of the conventional line CCD.

  FIG. 20 shows detection means for detecting the inclination in the scanning direction in FIG. 2, that is, detection means for detecting, for example, that the scanning line SL in FIG. 20 is inclined like SL '. Marks indicated by ML and MR are formed at both ends of the photoreceptor 1, and a mark indicated by MC is formed at the center. These marks are “F” -shaped marks composed of a line segment parallel to the scanning line and a line segment intersecting the scanning line SL at 45 °. These marks are detected by the sensors SSL, SSC, SSR, and the inclination of the scanning line is detected from the timing of the detection signal of the line segment parallel to the main scanning line of the marks ML, MR, and the marks ML, MC, MR are detected. The magnification in the main scanning direction is detected from the difference between the detection timings of the parallel line segments and the detection timing of the intersecting line segments (distance between both lines).

(2) Embodiment 2
A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a top sectional view of the exposure apparatus according to the second embodiment of the present invention. The same parts as those in FIG. 2 are given the same reference numerals. 6 is a cross-sectional view taken along line AX-BX-CX in FIG.

  The frame body 401 that supports the light source and the scanning optical system is supported at three locations of a first fulcrum T10, a second fulcrum T20, and a third fulcrum T30 by a support plate 417 fixed to the image forming apparatus main body. The structure of the third support portion at the third fulcrum T30 is as follows.

  A coupling member 447 that couples the frame 401 and the support plate 417 includes a sphere 447a. On the other hand, a spherical bearing 446 that supports the spherical body 447 a so as to be rotatable in all directions including up, down, left and right is fixed to the support plate 417. With this support structure, the frame body 401 is supported so as to be rotatable in all directions including the upper, lower, left, and right around the third fulcrum T30. Thus, in the present embodiment, the third fulcrum T30, which is a fixed point support part among the three support parts, is in a plane perpendicular to the scanning plane on the plane including the optical axis center AX of the scanning optical system. Is provided. When the third fulcrum T30 is arranged in such a plane, the movement adjustment of the exposure apparatus in the plane parallel to the scanning plane is performed almost symmetrically with respect to the scanning area. The magnification can be adjusted equally to the left and right with respect to the center of the scanning area in the main scanning direction.

  FIG. 6 shows the structure of the first support portion at the first fulcrum T10 provided with the first adjusting means for adjusting the inclination of the light beam in the main scanning direction. Next, the structure of the first support portion will be described.

  Two engagement pieces 426 and 427 made of a thin elastic metal plate are fixed to the frame 401 at one end. On the other hand, the support plate 417 is provided with a drive screw 425 so that it can rotate and does not move up and down. The first fulcrum T10 is an intersection of the surface formed by the engagement pieces 426 and 427 and the rotational axis of the drive screw 425. The screw portion of the drive screw 425 held by a holding member (not shown) is engaged with the engagement pieces 426 and 427. A gear 425a is fixed to the drive screw 425, and the gear 425a is driven and rotated by the motor M10 via the gear 434. A spring 471 that assists in pressing the frame body 401 downward is installed between the frame body 401 and the support plate 417. The motor M10, the drive screw 425, and the engagement pieces 426 and 427 constitute first adjustment means.

  The engagement pieces 426 and 427 receive a load in the lower part of FIG. 6 and also serve as receiving members for the support plate 417 of the exposure apparatus 30. In addition, the engagement position with the engagement pieces 426 and 427 is moved in the vertical direction by the rotation of the drive screw 425. Accordingly, the exposure apparatus 30 forms a straight line connecting the third fulcrum T30 and the second fulcrum T20. Needless to say, a clearance is required between the engagement pieces 426 and 427 and the drive screw 425 in the direction perpendicular to the axial direction of the drive screw 425 since the rotation operation is performed as the rotation center. Thus, the engagement pieces 426 and 427 are also receiving members for the support plate 417 of the exposure apparatus 30, and the position regulation in the direction perpendicular to the axial direction of the drive screw 425 is the first adjustment by providing another regulation means. The means do not cause any trouble.

  As the other restricting means, a second adjusting means described later may be used, or for example, a separate position restricting means may be provided by the means shown in the first embodiment or a similar means.

  When the motor M10 rotates, the frame body 401 rotates around the third fulcrum T30 as indicated by the arrow X by the engaging action of the engaging pieces 426, 427 and the drive screw 425. The scanning line inclination of the light beam L is adjusted by the vertical movement of the frame 401 in the X direction.

  The structure of the second support portion at the second fulcrum T20 provided with the second adjusting means is as follows.

  The frame body 403 of the second support portion is integrally formed with the frame body 401, and the engagement pieces 466 and 467 are further fixed. On the other hand, rising portions 468 and 469 are formed on the support plate 417, and the drive screw 431 is rotatably supported. A gear 432 is fixed to the drive screw 431 and is rotatably connected at a high reduction ratio by the rotation of the motor M20 and the worm gear 465 fixed to the rotation shaft thereof. The extending portion of the frame body 403 comes into contact with the non-threaded portion of the drive screw 431, and the vertical positions of the frame body 401 and the support plate 417 are restricted. The second fulcrum T20 is an intersection of the surface formed by the engagement pieces 466 and 467 and the rotation axis of the drive screw 431. Further, a spring 472 that assists in pressing is installed. Further, the engagement pieces 466 and 467 are engaged with the drive screw 431, and a spring 474 is provided to prevent engagement backlash between the engagement pieces 466 and 467 and the drive screw 431. The rotation of the motor M20 is transmitted to the drive screw 431, and the engagement pieces 466 and 467 move left and right by this rotation. The motor M20, the drive screw 431, and the engagement pieces 466 and 467 constitute second adjustment means.

  As described above, the engagement pieces 466 and 467 move to the left and right with respect to the support plate 417 by the rotation of the motor M20. That is, the contact point between the drive screw 425 and the engagement pieces 426 and 427 at the first fulcrum T10, and the extending portion 403a of the frame body 403 at the third fulcrum T30 and the second fulcrum T20 are in contact with the non-screw part of the drive screw 431. The frame 401 rotates around the third fulcrum T30 in the plane including This rotation operation adjusts the left-right magnification variation in the main scanning direction.

  FIG. 10 shows a specific example of the support structure of the frame 401 at the third fulcrum T30. In FIG. 10A, three spheres 446a, 446b, and 446c supported at three points are used as the sphere bearings that support the sphere 447a of the coupling member 447. The spherical body 447a is pressed against the balls 446a, 446b, and 446c by a pressing member 446d made of an elastic material. In FIG. 10 (b), as a spherical bearing for supporting the spherical body 447a of the coupling member 447, a circular hole smaller than the diameter of the spherical body 447a is formed in the support plate 417, and the spherical body 447a is inserted, as in FIG. 10 (a). The spherical body 447a is brought into pressure contact with the support plate 417 by a pressing member 446d made of an elastic material. In FIG. 10C, the sphere of the coupling member 447 is held by drawing the sphere bearing 446.

  FIGS. 10D and 10E show modified examples of the engagement pieces 426 and 427 in FIG. 6 and the engagement pieces 466 and 467 in FIG. In the example of FIG. 10D, the protruding portions BSA and BSB are provided on one flat plate BS, and the protruding portions BSA and BSB form engaging pieces 426 and 427 or engaging pieces 466 and 467. In the example of FIG. 10 (e), the protrusions CSA and CSB are provided on the plate CS provided with the stepped part CSC, and the engagement pieces 426 and 427 or the protrusions 466 and 467 are formed by these protrusions. In the example of FIG. 10E, the protruding portions CSA and CSB are formed by shifting the positions by the step CSC. As a result, the engagement pieces 426 and 427 engage with the drive screw 425 with a phase shift corresponding to the pitch of the drive screw 425, and the engagement pieces 466 and 467 have a phase corresponding to the pitch of the drive screw 431. The drive screw 431 is engaged with a deviation. In the example shown in FIG. 10D, it is preferable that an elastic plate is used as the flat plate GS and is elastically deformed when engaged with the drive screw so that appropriate engagement is performed. In the example shown in FIG. 10 (e), the position of the protrusions CSA and CSB is shifted by the stepped portion CSC corresponding to the pitch of the drive screw, so that the engagement is performed properly and accurate adjustment is possible. Become.

  FIG. 11 shows an example of first adjusting means for adjusting the inclination of the scanning optical system in the main scanning direction and second adjusting means for adjusting variation in magnification in the main scanning direction of the scanning optical system.

  In FIG. 11A and FIG. 11B, a drive screw (drive male screw) driven by a motor (not shown) is screwed into an engagement block 481 having a female screw 481c. The block 481 is fixed to a recess provided in the frame body 401. The frame 401 moves up and down relatively with respect to the support plate 417 by the rotation of the drive screw 425. This movement is a rotational movement of the exposure apparatus 30 about the second fulcrum T20 and the third fulcrum T30. As described above, in the adjustment in which the rotational motion of the exposure apparatus 30 is caused by the linear motion of the engagement block 481, there is theoretically a mismatch between the rotational motion and the linear motion. However, when the distance between the first fulcrum T10, which is the center of rotation, and the second fulcrum T20 where the linear motion is performed is sufficiently far compared to the distance moved by the adjustment, the misalignment may be caused by a gap in the screw portion. Since it is absorbed, the mismatch does not become an adjustment problem. As a condition of the adjustment mechanism that can absorb the mismatch, a gap of the screw portion that enables an adjustment amount that is 1.5 times or more the maximum adjustment amount of the exposure apparatus 30 (the maximum value of the distance moved by adjustment) is set. It has been confirmed that the condition of holding is desirable.

  11C and 11D, an engagement block 482 having a female screw 482c is coupled to the frame body 401 by rod-shaped coupling members 482a and 482b that fit into the engagement block 482. A drive screw 425 driven by a motor (not shown) is screwed into a female screw 482c of the engagement block 482. By driving the gear 425a, which fixes the drive screw 425 formed with the male screw, with a motor, the engagement block 482 moves up and down, and the relative position of the frame 410 with respect to the support plate 417 changes. In the example of FIGS. 11C and 11D, since the engagement block 482 can rotate with respect to the coupling members 482a and 482b, the mounting error of the drive screw 425 and the like is absorbed by this rotatable mounting structure. Even if the perpendicularity of the drive shaft 425 with respect to the support plate 417 is not precisely managed when the drive shaft 425 is attached, the engagement member 482 is self-adjusted, which is effective in reducing the number of assembly steps.

  In FIGS. 11 (e) and 11 (f), a drive screw 425 (drive male screw) driven by a motor (not shown) penetrates the hole of the engagement block 483. The engagement block 483 is fixed to a recess provided in the frame body 401. FIG. 11F is an enlarged cross-sectional view taken along line DX-DX in FIG. 11E. As shown in the figure, the pointed portion of the engaging member 484 screwed into the engaging block 483 is the drive screw 425. Is engaged with the screw part. The first fulcrum T10 is a contact point between the pointed head of the engaging member 484 and the drive screw 425. By the rotation of the drive screw 425, the exposure apparatus 30 rotates about the straight line connecting the second fulcrum T20 and the third fulcrum T30. While the movement of the engagement block 483 by the drive screw 425 is a linear movement, the exposure apparatus 30 performs a rotational movement as described above. The adjusting mechanism using the engaging member 484 absorbs the mismatch between the linear motion and the rotational motion, and the squareness is set when the drive screw 425 is attached to the support plate 417. It is possible to reduce the number of assembling steps in the assembling process such as precisely managing.

  The adjustment means shown in FIGS. 11A to 11F is an example of a first adjustment means for adjusting the inclination in the main scanning direction, but the example shown in FIG. 11G is a variation in magnification in the main scanning direction. It is a specific example of the 2nd adjustment means which adjusts.

  In FIG. 11G, the drive screw 431 is supported by the rising portions 468 and 469 fixed to the support plate 417, and the drive screw 431 (drive male screw) on which the male screw is formed is shown in FIG. The engagement block 491 having such a female screw is acted. The engagement block 491 is coupled to the frames 403 and 401 by the provided coupling members 491a and 491b.

  By rotating and driving the gear 432 that fixes the drive screw 431 by a motor (not shown), the frame 401 moves in the horizontal direction, and the variation in magnification in the main scanning direction of the scanning optical system is adjusted. The spring 474 is provided to absorb the play of the adjustment mechanism. Further, the frame body 401 is provided with a protruding portion 492 and the support plate 417 is provided with a receiving portion 493 corresponding to the protruding portion 492. The protruding portion 492 and the receiving portion 493 constitute an interval holding unit, and the interval between the exposure apparatus 30 and the support plate 417 is held constant by the interval holding unit. Reference numeral 472 denotes an elastic member that presses the protruding portion 492 against the receiving portion 493.

(3) Embodiment 3
FIG. 12 shows a third embodiment of the present invention. 12A is a perspective view of the exposure apparatus 30 as viewed obliquely from below, and FIG. 12B is a cross-sectional view of the support structure of the exposure apparatus 30. FIG.

  The frame 401 of the exposure apparatus 30 is supported by the image forming apparatus main body at a third fulcrum T30, which is a fixed point, by a coupling member 500 having a sphere supported by a sphere bearing (not shown) at the tip, and the third fulcrum T30. It is supported by a support bar 502 having a shape along a center arc. That is, the support bar 502 penetrates the guide member 501 formed of an arc tube fixed to the frame body 401 by the support member 530. As shown by the arrow V, the frame 401 is guided by the guide member 50 as the second support means and rotated about the third fulcrum T30 as a fulcrum by the drive means (not shown), and the scanning optical system of the exposure apparatus 30 Variations in magnification in the main scanning direction are corrected. Thus, the driving means, the support rod 502, and the guide member 501 constitute a magnification adjusting means. The frame 401 is supported rotatably in the vertical and horizontal directions by the coupling member 500 and the spherical bearing 505 as the first support means for forming the third fulcrum T30.

(4) Embodiment 4
FIG. 13 is a perspective view of an exposure apparatus according to Embodiment 4 of the present invention.

  The exposure apparatus 30 has a unit structure assembled on the support member 600. A support shaft 603 is supported by rising portions 601 and 602 fixed to the end portion of the support member 600. Tubular coupling members 605 and 606 are rotatably engaged with the support shaft 603. The coupling members 605 and 606 are fixed to a box-shaped frame 604. In the frame 604, scanning optical systems such as the polygon mirror unit 31, the fθ lens 32, the second cylindrical lens 33, and the like are provided. Engagement pieces 607 and 608 are fixed to the side of the frame 604 facing the side where the coupling members 605 and 606 are provided. The engagement pieces 607 and 608 engage with a drive screw 609 provided in the image forming apparatus main body. A gear 610 is fixed to the drive screw 609.

  By rotating the drive screw 609 with a motor as a drive source (not shown), the frame 604 rotates about the shaft 603 by the action of the engagement pieces 607 and 608, and the exposure apparatus 30 tilts in the main scanning direction. Is adjusted. Thus, the motor, the drive screw 609, and the engagement pieces 607 and 608 constitute an inclination adjusting means.

  The description of the adjustment of the inclination in the main scanning direction in the third embodiment and the correction of the variation in magnification in the main scanning direction in the fourth embodiment are omitted, but the adjustment function in the first and second embodiments or any other well-known information is omitted. The adjusting means can be used.

  Also, by adjusting the entire unit in the fourth embodiment with the adjustment mechanism in the third embodiment, the number of parts increases, but the tilt in the main scanning direction and the variation in magnification in the main scanning direction are more reliably adjusted. It can be performed.

  The exposure apparatus 30 having the adjustment mechanism described above is used in the image forming apparatus shown in FIG. 1, but is not limited to the image forming apparatus shown in FIG. 1, for example, an image forming apparatus described next as a fifth embodiment, That is, an image forming apparatus that forms a toner image of each color on a photosensitive member, and transfers the formed plurality of color toner images to a recording sheet through an intermediate transfer member, or a toner image of each color formed on a plurality of photosensitive members. Can also be used in an image forming apparatus that forms a full-color image by transferring the toner image onto the recording paper or transferring it onto the intermediate transfer belt and then transferring it onto the recording paper.

(5) Embodiment 5
Embodiment 5 will be described with reference to FIGS. 14 is a view showing the entire image forming apparatus according to Embodiment 5 of the present invention, FIGS. 15 to 19 are views showing a coupling structure between exposure apparatuses in the image forming apparatus shown in FIG. 14, and FIG. It is a figure which shows the detection means which detects these positional relationships.

  A belt-like intermediate transfer member 50 in which a semiconductive layer is formed on a conductive substrate is stretched between a driving roller 51 and a driven roller 52 by an appropriate tension by a tension roller 53 as indicated by an arrow. It is built. Opposite to the intermediate transfer member 50, an image forming unit YU for yellow image, an image forming unit MU for magenta image, an image forming unit CU for cyan image, and an image forming unit KU for black image are provided. Each image forming unit includes a drum-shaped photoconductor U1, a charging device U2, an exposure device U3, a developing device U4, and a cleaning device U5. Note that, regarding these components in the image forming unit, only the image forming unit for yellow image is given a reference numeral. A transfer device 54 is provided facing the image forming units YU, MU, CU, and KU with the intermediate transfer member 50 interposed therebetween.

  Paper feed cassettes 60A, 60B and 60C for storing recording paper are provided at the lower part of the apparatus, and a manual paper feed tray 60D is provided at the side. Paper feeding units 61A, 61B, 61C, and 61D for carrying out the recording paper P from each paper feeding cassette and the manual paper feeding tray are provided. Each of the paper feeding units 61A, 61B, 61C, and 61D includes a feed roller that feeds the accumulated recording paper from above, a separation conveyance roller that separates and conveys the recording paper, and a separation roller. 56 is a conveying belt for conveying the recording paper P to the fixing device 57, 57 is a fixing device having a heating roller and a pressure roller, 58 is a cleaning device for cleaning residual toner on the intermediate transfer member 50, 59 is a paper discharge tray, A reading device 64 reads a document and generates image data.

  In each image forming unit, a toner image is formed on the photoreceptor U1 by charging by the charging device U2, exposure by the exposure device U3, and development by the developing device U4. The toner images are formed on the intermediate transfer member 50 by the transfer device 54. The toner images are formed on the intermediate transfer member 50 so as to be overlapped to form a full-color image.

  The full-color image formed on the intermediate transfer member 50 is transferred to the recording paper P by the transfer device 55 and fixed by the fixing device 57. The recording paper P on which a full-color image is formed is discharged to a paper discharge tray 59.

  The image forming units YU, MU, CU, and KU are required to form toner images of each color on the intermediate transfer member 50 with an accuracy of micron units. When such a condition is not satisfied, the full-color image formed on the intermediate transfer member 50 has a color shift. Accordingly, the positions of the image forming units YU, MU, CU, and KU, in particular, the positions between the exposure apparatuses U3 of each unit are required to be set with a high degree of accuracy.

  In the present embodiment, as shown in FIG. 15, exposure apparatuses U3 of image forming units YU, MU, CU, and KU, that is, four exposure apparatuses are vertically coupled. As shown in FIG. 15, the yellow image exposure device U3 has a cyan image on support plates 7A and 7B as support means at both ends, and the magenta image exposure device U3 has a cyan image on support plates 8A and 8B as support means. The exposure apparatus U3 is fixed to support plates 9A and 9B as support means, and the black image exposure apparatus U3 is fixed to support plates 10A and 10B as support means. The support plates 7A, 8A and 8A are supported. The support plate 9A, the support plate 9A and the support plate 10A, the support plate 7B and the support plate 8B, the support plate 8B and the support plate 9B, and the support 9B and the support plate 10B are coupled and fixed to each other.

  As shown in FIG. 16, the exposure apparatus U3 includes a semiconductor laser 35 as a light source, and an optical system including a collimator lens 36, a first cylindrical lens 37, a polygon mirror unit 31, an fθ lens 32, and a second cylindrical lens 33. . Reference numeral 39 denotes an index sensor, and 38 denotes a mirror for guiding a light beam to the index sensor 39.

  Each of the support plates 7A, 7B, 8A, 8B, 9A, 9B, 10A, and 10B has a large number of protrusions, and is coupled by a fixing means that fixes the support plates in a form in which these protrusions are alternately inserted. Is done. FIGS. 17 and 18 show examples of coupling of the support plates 8A and 9A. FIG. 17 shows a state before the support plates are joined, and FIG. 18 shows a state where the support plates are joined together. The image forming units YU, MU, CU, and KU are in a state in which the image forming units YU, MU, and CU are adjusted to desired positions by an image forming unit positioning unit (not shown) with respect to the image forming unit KU. At the stage where the position of the image forming unit is adjusted, each image forming unit is in a state of being floated in space by an adjusting unit (not shown), and the mutual gaps of the plurality of protrusions include the adjustment allowance in this adjusting process. There is enough clearance. The image forming units YU, MU, CU, and KU are configured as one large image forming unit by fixing the large number of protruding portions by a connecting means described later.

  18A is a side view of the coupling portion, and FIG. 18B is a front view of the coupling portion. As shown in FIG. 17, the protrusions 82 of the support plate 8A and the protrusions 91 of the support plate 9A are alternately inserted. The projecting portions 82 and 91 have bent portions 84 and 93 at their tip portions, respectively, and after joining the support plates 8A and 9A, as shown in FIG. 18, molten resin RE is put in the gap between the bent portions 84 and 93. The resin RE is filled by pouring. The joint portion filled with the resin RE is in the state shown in FIG. 18, and the resin RE is filled in the gap between the folded portion 93 having the surface RS intersecting with the direction F separating the support plates 8A and 9A and 84. Therefore, the resistance of the resin RE itself acts against the force in the direction F separating the support plates 8A and 9A, so that the support plates 8A and 9A are firmly coupled.

  The support plate 7A and the support plate 8A, the support plate 9A and the support plate 10A, the support plate 7B and the support plate 8B, the support plate 8B and the support plate 9B, and the support plate 9B and the support plate 10B are injected and filled with the resin RE as described above. Combined.

  In this way, the four exposure apparatuses U3 are firmly coupled to each other. FIG. 19 shows another example of coupling of exposure apparatuses. In this example, each of the support plates 7A, 8A, 9A, and 10A is provided with a large number of protrusions, but these protrusions have bent portions as in FIGS. It is not provided.

  In the example of FIG. 19, after the support plates of adjacent exposure apparatuses are joined together like the support plates 7A and 8A and 8A and 9A, the two are joined by injecting the resin RE into the joint portion between them.・ Fix it. In this case, as the resin RE, the same kind of resin material as the resin constituting the support plates 7A and 8A is used. By using the same resin material for the support plate and the filling resin RE, the linear expansion coefficient of the material is the same, and distortion of the image forming portion due to a temperature rise of the image forming apparatus is prevented. Further, when the molten resin is filled in the gap, the resin-filled portions of the support plates 7A, 7B, 8A, 8B, 9A, 9B, 10A, and 10B are affected by heat and the surface becomes rough, The bonding method is stronger than the bonding method in which no is added.

  Adjacent support plates other than the support plates 7A, 8A and 9A are also coupled in the same manner. Of course, the coupling structure between the exposure apparatuses in the present embodiment can also be applied to the coupling between the exposure apparatuses 30, 30M, 30C, and 30K in FIG.

  In order to improve the image quality of the color image forming apparatus, it is necessary to precisely adjust and assemble the positions of the image forming units YU, MU, CU, and KU between the exposure apparatuses U3. In the present embodiment, the assembly shown in FIG. 15 is assembled by the steps described below.

  First, the support plates 7A, 7B, 8A, 8B, 9A, 9B, 10A, and 10B are fixed to the exposure apparatus U3. The exposure apparatus U3 to which the lowermost support plates 10A and 10B are attached is fixed to a jig according to an attachment reference (not shown). The other exposure apparatuses U3 are stacked in order from the bottom, but the exposure apparatuses other than the lowest stage are held by the arms of a jig (not shown) and kept in a floating state. Next, the position of the other exposure apparatus is adjusted so as to fall within the range of the design value with respect to the lowermost exposure apparatus. The adjustment is performed by accurately measuring the distance between the exposure apparatuses U3.

  The molten resin RE is poured into a gap formed between the support plates whose positions are adjusted, and the space between the support plates is fixed.

  As shown in FIG. 20, the intermediate transfer member 50 stretched between the driving roller 51 and the driven rollers 52 and 53 has a large number of “F” -shaped position adjustments by exposure of a fixed pattern by the exposure device U3. Marks ML, MC, and MR are formed. The mark ML is formed at the left end of the photoconductor 50, the mark MC is formed at the center of the photoconductor, and the mark MR is formed at the center of the photoconductor 50. Each mark has a “F” shape formed of a line segment parallel to the main scanning line SL and a line segment intersecting the main scanning line SL at an angle of 45 °.

  Using the position detection information of the parallel line segments, the position in the sub-scanning direction between the exposure units U3 of the image forming units YU, MU, CU, and KU is adjusted, and the position detection information of the intersecting line segments is used. Thus, the position in the main scanning direction and the magnification in the main scanning direction of each exposure apparatus U3 are adjusted. The positions of the marks SSL, SSCL, and SSR are detected by the sensor SS. The sensor SS includes a light projecting element SS1 having an LED configuration that projects a light beam onto the photoconductor 50, a light receiving element SS2 that receives reflected light from the photoconductor 50, and a lens SS3.

  Adjustment of the position between the exposure apparatuses using the position detecting means shown in FIG. 20 is performed through an image forming test in which an image forming apparatus incorporating the assembled assembly shown in FIG. 15 is operated.

  With the above-described assembly process of the image forming apparatus, there is no positional deviation in the main scanning direction and the sub-scanning direction between the image forming units YU, MU, CU, and KU, and the inclination of the main scanning line and the variation in the magnification in the main scanning direction. Thus, an image forming apparatus capable of forming a high-quality color image without any color is formed.

30, 30Y, 30M, 30C, 30K exposure equipment,
31 Polygon mirror unit,
32 Fθ lens,
33 second cylindrical lens,
35 semiconductor laser,
36 collimator lens,
37 first cylindrical lens,
301, 417 support plate,
307, 401, 604 frame,
T1, T10 first fulcrum,
T2, T20 second fulcrum,
T3, T30 3rd fulcrum,
M1, M2, M10, M20 motors.

Claims (12)

An exposure apparatus having a laser light source and a scanning optical system that deflects light from the laser light source and emits a scanning light beam is supported at least at a first fulcrum, a second fulcrum, and a third fulcrum.
The first fulcrum and the second fulcrum are symmetrically positioned at both ends of the optical path formed by the scanning optical system, and the first fulcrum and the second fulcrum are sandwiched between the optical axes of the scanning optical system. Provided in
The third fulcrum is a fixed point provided in a plane perpendicular to the scanning plane on the plane including the optical axis of the scanning optical system,
A spherical bearing that rotatably supports the exposure apparatus in all directions is provided on the first support portion provided with the first fulcrum;
The movement of the first fulcrum is performed by using a straight line connecting the other two fulcrums as a rotation axis, and at least one of the other two fulcrums can move in a direction substantially perpendicular to the movement direction of the first support portion. And
The first support portion is composed of a drive screw and an engagement piece that engages with the drive screw,
The drive screw, the engagement piece, and a drive source for driving the drive screw constitute first adjustment means for adjusting the inclination of the scanning light beam in the main scanning direction on the first support portion,
An image forming apparatus characterized in that it is possible to adjust the inclination in the main scanning direction only by adjusting the first adjusting means. The image forming apparatus according to claim 1, characterized in Rukoto which have a spacing prevention member for preventing the separation of spheres the sphere bearing support. The image forming apparatus according to claim 2 , wherein the separation preventing member has elasticity . Together with the spherical body bearing supporting the spherical at three points, claim 2 or claim the separation preventing member is characterized Rukoto is pressed against the spherical body in contact with at least one point on said spherical bearing to the sphere The image forming apparatus according to 3. 3. The spherical bearing according to claim 2 , wherein the spherical bearing supports the spherical body in an annular shape, and the separation preventing member contacts the spherical body at at least one point to press the spherical body against the spherical bearing. Item 4. The image forming apparatus according to Item 3 . The image forming apparatus according to claim 1 , wherein the engagement piece includes two pieces that engage with the drive screw from opposite directions . The image forming apparatus according to claim 6 , wherein the two engagement pieces are formed as projecting portions extending from one common base portion . The image according to claim 6 or 7, wherein the two engaging pieces engage with the driving screw at a position shifted from each other by approximately ½ of the pitch of the driving screw. Forming equipment. The image forming apparatus according to claim 1 , further comprising a plurality of the exposure apparatuses, wherein each of the plurality of exposure apparatuses is provided with the first adjustment unit . Wherein the first adjusting means image forming apparatus according to claim 1, characterized in Rukoto to have a driving source comprising the motor. The image forming apparatus according to claim 1 , wherein the first adjustment unit includes a drive source including a laminated piezoelectric actuator . The second indicator provided with the second fulcrum is provided with second adjusting means for adjusting variation in magnification in the main scanning direction of the scanning light beam, and the variation in magnification is only adjusted by the second adjusting means. the image forming apparatus according to any one of claims 1 to 11, characterized in that made it possible to make adjustments.

Images