JP2008076460A - Optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical scanner in which a scanning lens is very simply fixed and the tilt and the bend of a scanning line are effectively adjusted, thus the deterioration of scanning line quality due to the deformation in the twisted direction of a scanning lens is prevented, and to provide an image forming apparatus. <P>SOLUTION: The optical scanner is provided with: a light source which is modulated and driven on the basis of an image signal; an optical deflector which deflects a light beam from the light source; a resin-made scanning lens which condenses the light beam deflected by the optical deflector onto a face to be scanned; and an optical box which holds the scanning lens; wherein the substantially central part of the scanning lens 3 in a longitudinal direction is fixed on the optical box 1, and adjustment means 11 and 12 are provided to movably hold the end part of the scanning lens 3 in the longitudinal direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical scanning device and an image forming apparatus equipped with the optical scanning device, such as a digital copying machine, a facsimile, and a printer.

  In recent years, digital copying machines, facsimiles, printers and the like have been improved in speed and image quality. In particular, as a high-speed color image forming apparatus, a large number of quadruple tandem type image forming apparatuses that form and superimpose four color toner images of yellow, magenta, cyan, and black on corresponding four drum type photoreceptors have been commercialized. ing. In order to improve the image quality of a quadruple tandem type image forming apparatus, it is necessary to accurately superimpose the plurality of developers, and various proposals (for example, see Patent Documents 1, 2, and 3) have been made.

In Patent Document 1, in the optical scanning device capable of appropriately correcting the curvature of the scanning line, the thickness of the folding mirror is gradually reduced from the side pressed by the adjusting screw toward the opposite side, and the second moment of section is obtained. Is asymmetric in the main scanning direction, and as a result of being pressed only at one end, it bends symmetrically in the main scanning direction, thereby effectively correcting the curvature of the scanning line with a good balance.
However, there is a problem that power in the main scanning direction is generated as a side effect of adjustment due to bending of the folding mirror, and it is difficult to align the main scanning dots over the entire scanning width.

In Patent Document 2, a long scanning lens is paired with an elastic member that is pressed by an elastic force in a direction that is orthogonal to the optical axis direction and orthogonal to the longitudinal direction, and is pressed from the elastic member. It has a support member that supports the scanning lens against the pressure, and there are three or more pairs of elastic members and support members. The support member is held by another holder member and can move in the direction of the pressing force. In addition, by providing a moving amount adjusting mechanism for the support member and adjusting with a screw element, the scanning line bending and inclination are corrected, and color misregistration is effectively suppressed.
However, in this method, there are a total of 5 or more support positions and intermediate adjustment portions at both ends of the scanning lens, the number of parts is large, the configuration is complicated, and the adjustment is complicated.

  In Patent Document 3, a holding member that holds a scanning lens, a fulcrum that is fixed to the holding member and supports the central portion of the scanning lens, and a spring member that pressurizes the left and right end portions respectively. The scanning line is bent by the configuration including the spring pressurizing unit and the first and second abutment support units that abut and support from the direction opposite to the pressurization direction of the first and second spring pressurization units, respectively. The correction mechanism and the scanning line inclination correction mechanism can be independently adjusted, and can be arranged in a simple configuration inside the optical box.

  On the other hand, with respect to the assembly and positioning of the scanning lens, a highly accurate and stable support method is required, and conventionally, a support method that reliably performs positioning in the vertical and horizontal directions with a plurality of leaf springs has been used. The above Patent Documents 1 to 3 are also modifications thereof, and it can be said that the contradictory functions of fixing and moving the scanning lens are complicatedly performed for adjusting the scanning line.

On the other hand, there is a means for fixing an optical element including a scanning lens more simply and at low cost by adhesion, and a detailed example thereof has been proposed recently (see, for example, Patent Document 4). In Patent Document 4, the scanning lens is fixed to the optical box with a surface substantially perpendicular to the optical axis at a position near the ineffective portion of the lens and the optical axis, and the thickness of the adhesive layer can be made uniform. The scanning lens can be adhered accurately and stably, and the scanning lens can be fixed to the optical box while maintaining the posture at the adjusted position.
JP 2005-024841 A JP 2005-266762 A JP 2006-078725 A JP 2003-222814 A

However, although Patent Document 4 mentions a fixing method by adhesion of a scanning lens and an initial scanning line inclination / main scanning piece magnification adjustment, for example, a scanning line bending caused by a temporal environmental variation due to a temperature variation or the like.・ Cannot handle tilt correction.
Long scanning lenses are generally injection-molded with high-precision molds, but due to recent aspherical and complicated lens surfaces, deformation in the twist direction has occurred, resulting in scan line bending and increased end beam diameter. The optical performance may be degraded. Conventionally, an effective countermeasure for this problem has not been disclosed.

  The present invention solves the above-mentioned problems, and the scanning lens can be fixed extremely simply as compared with the conventional one, and the inclination and bending of the scanning line can be adjusted effectively, and the scanning lens can be twisted in the twisting direction. It is an object of the present invention to provide an optical scanning device and an image forming apparatus that can prevent deterioration in scanning line quality due to deformation.

  An optical scanning device of the present invention is a light source that is modulated and driven based on an image signal, an optical deflection device that deflects a beam from the light source, and a resin-made material that condenses the beam deflected by the optical deflection device on a surface to be scanned. A scanning lens and an optical box that holds the scanning lens are provided. The central portion of the scanning lens in the longitudinal direction is fixed to the optical box, and the longitudinal end of the scanning lens can be moved with at least one degree of freedom. It has the adjustment means to hold | maintain, It is characterized by the above-mentioned.

  The optical scanning device of the present invention is characterized in that a substantially central portion in the longitudinal direction of the scanning lens is fixed to the optical box by adhesion.

  Further, the optical scanning device of the present invention is characterized in that the end of the scanning lens in the longitudinal direction is movable in the sub-scanning direction.

  Further, the optical scanning device of the present invention is characterized in that the end portion in the longitudinal direction of the scanning lens is rotatable in the twisting direction.

  Further, the optical scanning device of the present invention is characterized in that the width of the scanning lens in the sub-scanning direction is not uniform at the center and the end in the longitudinal direction of the scanning lens.

  The optical scanning device of the present invention is characterized in that the end of the scanning lens in the longitudinal direction is moved by at least one of a screw element, a linear motion element, and a pressure element.

  Further, the optical scanning device of the present invention is characterized in that the moving direction of both ends in the longitudinal direction of the scanning lens by the adjusting means is a direction to be tuned.

  Further, the optical scanning device of the present invention is characterized in that the moving directions of both ends in the longitudinal direction of the scanning lens by the adjusting means are opposite directions.

  In addition, the optical scanning device of the present invention includes a plurality of scanning lenses, and each scanning lens has a beam that reaches the center image height of a plurality of image carriers corresponding to each scanning lens substantially coincides in the sub-scanning direction. It is characterized by being fixed to.

  An image forming apparatus according to the present invention includes the optical scanning device according to the present invention.

  According to the present invention, it is possible to fix the scanning lens very simply and to effectively adjust the inclination and bending of the scanning line, and to prevent deterioration of the scanning line quality due to deformation of the scanning lens in the twisted direction. Can do.

  Embodiments of an optical scanning device and an image forming apparatus according to the present invention will be described below with reference to the drawings.

First, the optical scanning device will be described.
An optical scanning device is a device that scans a light beam (light beam) emitted from a light source as a light spot on a surface to be scanned (surface of a photosensitive drum), and includes a light source, a light deflecting device (light deflector), A coupling lens, an aperture stop, a cylindrical lens, a scanning lens, an optical box that holds the optical element in a predetermined position, a scanning lens fixing part that fixes the scanning lens to the optical box, and an end of the scanning lens Holding adjusting means. The scanning lens is made of resin, and the optical scanning device includes at least one scanning lens.

The method of optical scanning by the optical scanning device is as follows.
A light source such as a semiconductor laser is modulated and driven based on an image signal and emits a divergent light beam. The light beam emitted from the light source is coupled into a beam form suitable for the subsequent optical system by the coupling lens. The coupled light beam is a substantially parallel light beam. The light beam coupled by the coupling lens is incident on the cylindrical lens after the width of the light beam is regulated by the aperture stop so that a desired light spot is obtained on the surface to be scanned. The light is collected in the vicinity of the reflecting surface in the form of a long line in the main scanning direction. The optical deflecting device is rotated at a substantially constant speed by a motor or the like, and deflects the incident light beam from the cylindrical lens at a constant angular velocity. The light beam deflected by the optical deflecting device becomes a convergent light beam by the action of the scanning lens and is focused on the surface to be scanned to form an image as a beam spot, and optically scans the surface to be scanned at a substantially constant speed. Is done.
Hereinafter, the direction in which the optical scanning device optically scans the surface to be scanned is referred to as a main scanning direction, and the direction orthogonal to the main scanning direction is referred to as a sub scanning direction.

FIG. 1 is a perspective view partially showing a bottom surface portion of an optical box 1 of an optical scanning device. The material of the optical box 1 includes resin integral molding or aluminum casting.
The conventional optical box is composed of a box main part and a lid part whose upper surface is open like a lunch box. Recent optical boxes have a structure in which the lid is closed at the bottom for compatibility with compact and tandem color image forming apparatuses, and a complicated structure with a plurality of holes through which beams pass and a plurality of lids. Exists. FIG. 1 shows an example of a simple upward-opening optical box.

The optical box 1 holds optical elements constituting the optical scanning device, such as a light source, an optical deflection device, and a scanning lens, at predetermined positions. In addition, the optical box 1 has a function of sealing the inside of the optical scanning device so that the scanning beam is not interrupted due to dust and the amount of light does not decrease.
The long scanning lens 3 is fixed to the optical box 1 by bonding a substantially central portion in the longitudinal direction to a lens mounting portion 2 provided in the optical box 1. As a bonding method, for example, an ultraviolet curable adhesive is used, and the scanning lens 3 is fixed so as to be held at a predetermined position on the lens mounting portion 2. There are six degrees of freedom in positioning in the fixing in three spatial directions (x, y, and z directions in FIG. 4) and rotational directions around them. Here, x is the optical axis direction, y is the main scanning direction, and z is the sub-scanning direction.
The lens mounting portion 2 and the scanning lens 3 may be held in a shape that is in a fitted or abutted state and may be bonded and fixed, or the scanning lens 3 may be partially or wholly free with a jig or the like. Adhesive fixation may be performed while holding Further, an air bonding method in which the optical axis 100 of the scanning lens 3 is held and bonded so as to be fixed by an appropriate thickness of the bonding layer may be used.

Both ends (longitudinal direction) of the scanning lens 3 are sandwiched and restrained in the z direction by the leaf spring 10 fastened to the optical box 1 by the fixing screw 9 and the adjusting screws 11 and 12.
The end of the scanning lens 3 is held movably with a degree of freedom in at least one direction. That is, since the adjustment screws 11 and 12 can be screwed into screw bosses 21 and 22 provided in the optical box 1 and the adjustment amount can be changed independently, the end of the scanning lens 3 is z Direction and the rotation direction β around the y-axis (FIG. 4) can be adjusted.

  Hereinafter, an outline of the adjustment of the scanning line bending and the inclination will be described with reference to FIGS. In the following description, the “central part” or “end part” of the scanning lens refers to the central part or end part in the “longitudinal direction” of the scanning lens.

FIG. 3 is a schematic diagram showing adjustment of scanning line bending and inclination, and a focal line reference line D that is an optical center line in the z direction of the scanning lens 3 and a focal line EF that is convex upward. The focal line GH that protrudes downward is shown.
When the protruding amounts of the adjusting screws 11 and 12 are small, the leaf spring 10 presses both ends of the scanning lens 3 downward, so that the focal line becomes EF. When the adjustment screws 11 and 12 push the lower surface of the scanning lens 3 against the pressing force, the left side of the focal line is between E and G, and the right side of the focal line is an arbitrary position between F and H. Can be adjusted.
Further, the twist adjustment in the β direction can be performed by the difference in the protruding amount of the adjusting screws 11 and 12.

The torsion adjustment will be further described with reference to FIG.
When the scanning beam passing through the lens surface 30 of the scanning lens 3 passes through the optical axis 100, it enters a position near the image height 0 on the surface to be scanned 101.
Here, as described above, if the lens surface 30 is twisted due to lens molding and there is torsional deformation that rotates in the β direction around the y axis, the beam 110 reaching the end of the scanned surface 101 is intended. It shifts in the direction not to be moved and moves like the beam 111 and the beam 112.
Therefore, this deviation can be corrected by adjusting the twist of the scanning lens 3 in the β direction based on the difference in the protruding amounts of the adjusting screws 11 and 12.

  The scanning lens 3 shown in FIG. 1 has a shape in which the width of the central portion of the lens outer frame is narrowed in the optical axis direction in order to facilitate this torsion adjustment. With this shape, the torsional rigidity is lowered while maintaining the adjustment span of the end by keeping the distance between the adjustment screws 11 and 12 to a certain amount or more. Further, by reducing the width of a part of the outer frame, an expensive lens resin material can be saved, and the cost can be reduced.

  FIG. 5 is a conceptual diagram of scanning line adjustment in a quadruple tandem type image forming apparatus described in detail later. The quadruple tandem type image forming apparatus is an apparatus that forms images by superimposing and superimposing four color toner visible images of yellow, magenta, cyan, and black on corresponding four drum-type photoreceptors. FIG. 5 shows that the scanning surface is scanned in a state where four scanning lines 121, 122, 123, and 124 corresponding to the respective colors are curved in a bow shape. The arcuate curve corresponds to the GH state shown in FIG.

  Here, the relative distance in the sub-scanning direction at the center position of the scanning lines 121 and 122 is the distance 131, the relative distance in the sub-scanning direction at the center position of the scanning lines 122 and 123 is the distance 132, and the sub-scanning at the center positions of the scanning lines 123 and 124 is performed. A relative distance in the direction is a distance 133. In general, in a quadruple tandem type image forming apparatus, this distance is set at an equal interval, which is numerically about 80 mm to 120 mm. Since each scanning lens 3 is fixed at a substantially central portion, this distance is set as a unique reference value, and adjustment is performed only at the end portion. That is, the scanning lens corresponding to each color is adjusted and fixed so that the beam reaching the center image height of the photoconductor corresponding to each color substantially matches in the sub-scanning direction.

With respect to the end of the scanning line on the front side of the drawing, the relative distance between the end of the scanning line 121 and the scanning line 122 is the distance 141, the relative distance between the end of the scanning line 122 and 123 is the distance 142, and the end of the scanning lines 123 and 124 The relative distance between the parts is defined as a distance 143. If the distance 141 and the distance 131 are adjusted to be the same by the adjustment method described above, the dot positions of the center of the scanning lines 121 and 122 and the end portions on the near side coincide. The relative distances 142 and 143 may be adjusted similarly. The same applies to the relative distance of the end on the back side of the page.
As described above, the curved state of the four scanning lines 121, 122, 123, and 124 is fixed at the center, and the end portions are adjusted and matched, so that the overall dot position shift of the four colors is very simple. And it can be kept extremely small.

  Further, as the scanning line curve state, there can be an S-shaped curve such as EH or GF in FIG. 3, but in the present invention, since the center is fixed, each end can be adjusted as appropriate. It can easily cope with the curvature of the mold. This also functions as an adjustment to the scan line inclination in which the entire scan line is inclined. That is, in the present invention, by constraining the positional relationship with the optical box 1 at the three points of the center and both ends of the scanning lens 3, an arcuate or S-shaped scanning is achieved with a very simple configuration as compared with the conventional case. It is possible to provide an adjustment method capable of dealing with line bending and scanning line inclination.

  Furthermore, the four scanning lines 121, 122, 123, and 124 may be in the same curved state so that the entire adjustment effort is the smallest without making all of them coincide with the reference focal line D.

  In the embodiment described above, the two adjustment screws 11 and 12 are provided at each end so that the adjustment in the torsion direction can be performed. A configuration having only one adjusting screw at each end may be employed.

  Next, a method for fixing the central portion of the scanning lens will be described with reference to FIGS. 6 and 7 showing the present embodiment are diagrams corresponding to the case of referring to the direction of the section CC shown in FIG. 2 of the previous embodiment.

In the example shown in FIG. 6, cylindrical bosses 31 and 32 are integrally formed on the lower surface of the scanning lens 103 so as to be aligned in the optical axis direction, and a circular reference hole 41 and an elongated hole provided in the lens mounting portion. When the boss 31 and the boss 32 are respectively fitted in the secondary reference hole 42, the position and orientation of the optical axis are determined. Mounting claws 43 and 44 are integrally molded on the optical box 101, and the lower portion of the outer frame of the scanning lens 103 is hooked from both sides to be fixed in the z direction.
According to this method, the center portion of the scanning lens can be fixed without using any adhesive, and assembly is easy and cost reduction can be achieved. Also, disassembly considering recycling is easy.

  In the example shown in FIG. 7, instead of the boss 31 shown in FIG. 6, the scanning lens 203 is fixed to the optical box 201 by thermally crimping the tip of the boss 33 having a length protruding from the lower surface of the optical box 201. . According to this method, the mounting claws 43 and 44 as in the example shown in FIG. 6 are unnecessary, and the fixing reliability is high. In addition, disassembly is easier than a fixing method using an adhesive.

  Next, another example of the z-direction adjusting means at the end of the scanning lens will be described with reference to FIGS.

FIG. 8 is a diagram showing another example of the z-direction adjusting means at the end of the scanning lens. (A) A front view of the end of the scanning lens viewed from the optical axis direction, and (b) J in the front view. It is a top view which is -J cross section.
In this example, one adjusting screw 13, a compression coil spring 14, and a nut 15 are used.
A bag-shaped nut storage portion 35 is provided at the outermost end portion of the scanning lens 303 so that two or more of the six nut end surfaces are restricted to prevent rotation. The nut 15 is accommodated in the nut accommodating portion 35 from the side (here, in the optical axis direction), and is screwed into the adjusting screw 13. The adjusting screw 13 passes through a hole formed in the lower surface of the optical box 301 from below, and can adjust the end of the scanning lens 303 in the z direction via the compression coil spring 14.

  According to this example, the configuration of the adjustment mechanism portion is compact and can be easily added to the conventional optical scanning device. Further, the use of the nut 15 has an advantage that an extra rotational moment is not applied and adjustment can be performed smoothly. Of course, an internal thread may be formed near the end of the scanning lens 303 without using a nut in order to achieve a simpler configuration within a range where there is no problem in adjustment accuracy.

FIG. 9 is a diagram illustrating another example of the z-direction adjusting means at the end of the scanning lens, and is a front view of the end of the scanning lens as viewed from the optical axis direction.
In this example, the screw boss 23 and the pressing portion 24 are integrally molded in the optical box 401, and the screw receiving portion 36 is formed at the end of the scanning lens 403. The adjustment screw 13 passes through the hole provided in the screw receiving portion 36 from above and is screwed into the screw boss 23. The scanning line bending can be adjusted by applying a force to the end of the scanning lens 403 lifted upward by the pressing portion 24 in the direction in which the adjustment screw 13 faces.

  According to this example, the number of parts is the smallest and very simple and low-cost, and unlike the other examples described above, the screwing direction of the adjusting screw is from the top. There is an advantage that the initial adjustment of the apparatus or the image forming apparatus is easily performed when the adjustment is performed in the process.

  In the examples shown in FIGS. 8 and 9, both ends of the scanning lens are pressurized by a pressurizing unit, and the z direction is adjusted by a screw element in the opposite direction. The pressurizing unit can serve the above purpose. If so, the form is not particularly limited.

Next, still another example of the z-direction adjusting means at the end of the scanning lens will be described with reference to FIG.
In this example, as shown in FIG. 10A, the two adjustment screws 16 and 17 can be easily adjusted in the direction in which both ends of the scanning lens 503 are synchronized or in the opposite direction. Pressurizing means such as a leaf spring as described above is applied to both ends of the scanning lens 503 from above, and the scanning line is adjusted by applying a force facing them from below.

  The adjusting screw 16 is screwed onto the lower surface of the optical box 1 from below and is screwed to lift the center of the arm 50 upward. One end of the arm 50 lifts the arm 60 upward via the contact portion 51 and the other via the adjusting screw 17 screwed to the other end. The contact portions 61 and 62 at both ends of the arm 60 pass through the optical box 501 and apply an upward force to the end portion of the scanning lens 503. By adjusting the adjustment screw 16 with this configuration, the arms 50 and 60 are moved in parallel in the vertical direction and pressed in a direction in which the moving directions of both ends of the scanning lens 503 are synchronized. Can be adjusted. Further, by adjusting the adjusting screw 17, the arm 60 swings like a seesaw and the moving directions of both ends of the scanning lens 503 are pressed in opposite directions, so that the scanning line inclination is adjusted rotationally symmetrically. be able to.

  As shown in the side view (b), the arms 50 and 60 are penetrated by the adjusting screw 16 in the center. Non-rotating stoppers 53 and 54 projecting to the side of the arm 50 abut against the side surface of the arm 60, and the arm 60 is prevented from rotating at a portion where the abutting portions 61 and 62 penetrate the optical box 501. Therefore, there is no shift caused by the screw adjustment in the tuning direction or the opposite direction, and accurate and reliable adjustment can be performed.

As described above, in the example shown in FIG. 10, the arcuate scanning line curve can be easily adjusted only by the adjusting screw 16. Further, for example, the S-shaped scanning line curve or the scanning line inclination can be easily adjusted only by the adjusting screw 17.
In addition, although the configuration in which both the bow-shaped scanning line curve and the S-shaped scanning line curve or the scanning line inclination are adjusted with two screws has been described, either one is adjusted according to the required function or cost. It is also possible to simplify the configuration in which only the function is adjusted with a single screw.

In the embodiments described so far, the adjustment method using a simple screw element has been mainly described. However, the adjustment means uses transmission by rotation of a stepping motor, a cam, an actuator that moves linearly, or the like. Obviously no problem at all. That is, the adjusting means may be any of a screw element, a linear motion element, and a pressure element.
Further, the adjustment method described above is not limited to manual initial adjustment, but is used for adjusting the actual beam position deviation or the dot position deviation on the surface to be scanned as means for adjusting the scanning line position deviation over time. Of course, the present invention can also be applied to an adjustment method for detecting and feeding back a deviation of a developed image formed with a developer.

Next, the image forming apparatus according to the present invention will be described.
FIG. 11 is a central cross-sectional view showing an embodiment of an image forming apparatus according to the present invention, which is a tandem type laser printer advantageous for light beam output of a color image.
The image forming apparatus includes an optical scanning device 200 including scanning optical systems corresponding to cyan (C), magenta (M), black (K), and yellow (Y), and a photoreceptor 1X (X : Y, M, C, K, the same shall apply hereinafter), a conveyance belt 80, a fixing device 300, a paper feed cassette (not shown) provided with transfer paper (not shown), and a paper discharge tray (not shown).

  Above the transport belt 80, a photoconductive photosensitive member formed in a cylindrical shape as an image carrier that is exposed by the optical scanning device 200 to form an electrostatic latent image is located upstream in the moving direction of the transport belt 80. To yellow (1Y), magenta (1M), cyan (1C), and black (1K). The diameters of the photoreceptors 1X are all the same.

  Around the photoreceptor 1X, process members according to an electrophotographic method (electrophotographic process) such as a charging unit 2X, a developing unit 4X, a transfer roller 6X, and a cleaning device 5X are sequentially arranged. A corona charger can also be used as the charging means.

  Around the conveying belt 80, a registration roller (not shown) and a belt charging charger (not shown) are disposed upstream of the photosensitive member 1X in the transfer paper conveying path, and the transferring paper is conveyed more than the photosensitive member 1X. A belt separation charger (not shown), a charge removal charger (not shown), a cleaning device (not shown), and the like are sequentially arranged on the downstream side of the path.

  As described above, in the image forming apparatus, the photoreceptors 1Y, 1M, 1C, and 1K are scanned surfaces set for the respective colors, and the scanning optical systems are provided in a one-to-one correspondence relationship with the respective surfaces. However, the light polarizer is shared by each color.

The optical scanning device 200 is an optical writing device that performs optical writing on the photosensitive member 1X, and executes an exposure process of an electrophotographic process. The optical scanning device 200 scans the surface of the photosensitive member 1X that is uniformly charged by the charging unit 2X. Scan to form an electrostatic latent image. The formed electrostatic latent image is a so-called negative latent image, and the image portion is exposed. This electrostatic latent image is reversely developed by the developing means 4X, and a toner image is formed on the photoreceptor 1X.
As the optical scanning device, the above-described optical scanning device according to the present invention is used.

  The uppermost sheet of transfer paper stored in the paper supply cassette is fed by a paper feeding roller (not shown), and the transferred transfer paper is caught by a registration roller at the leading end. The registration roller sends the transfer paper to the transfer unit in accordance with the timing at which the toner image on the photoreceptor 1X moves to the transfer position. The transferred transfer paper is superimposed on the toner image at the transfer portion, and the toner image is electrostatically transferred by the action of the transfer roller.

  The transfer paper onto which the toner image has been transferred is sent to the fixing device 300, where the toner image is fixed by the fixing device 300, passes through a conveyance path (not shown), and is discharged onto a paper discharge tray by a paper discharge roller (not shown). The surface of the photoreceptor 1X after the toner image is transferred is cleaned by the cleaning device 5X, and residual toner, paper dust, and the like are removed.

In the tandem type image forming apparatus configured as described above, for example, when a multi-color mode (full color mode) is selected, each photosensitive member is exposed by an exposure unit (not shown) according to an image signal of a corresponding color. An electrostatic latent image is formed on each photoconductor. These electrostatic latent images are developed with the corresponding color toners to become toner images, electrostatically attracted onto the conveyance belt 80, and sequentially transferred onto the conveyed transfer paper, so that they are superimposed. It is done. Then, the image is fixed as a color image by the fixing device 300, and the transfer sheet is discharged to a discharge tray.
When the single color mode is selected, the photosensitive members and process members of other colors are in a non-operating state as a certain color S (any one of Y, M, C, and K). Here, only on the photoreceptor 1S, an electrostatic latent image is formed by exposure of the exposure unit, developed with a toner of a certain color S to become a toner image, and electrostatically adsorbed on the conveyance belt 80, It is transferred onto the transfer paper that is conveyed. Then, the image is fixed as a single color image by the fixing device 300, and the transfer sheet is discharged to a discharge tray.

  If the above-described optical scanning device according to the present invention is applied to this image forming apparatus, the inclination and bending of the scanning line can be adjusted, and a higher quality output image can be obtained.

FIG. 4 is a sub-scan sectional view of an optical system before an optical deflector, showing a main part of a diffractive optical element for splitting light beams included in an optical scanning device according to the present invention. (A) The projection figure from the optical axis direction of an optical operation apparatus (FIG. 1 arrow A), (b) Side view (FIG. 1 arrow B). It is a schematic diagram shown about a scanning line curve and adjustment of inclination. It is a schematic diagram which shows the mode of the scanning beam which passes a scanning lens surface and reaches a to-be-scanned surface. It is a conceptual diagram of adjustment of the scanning line in the continuous tandem type image forming apparatus. It is a figure which shows another fixing method of the center part of a scanning lens. It is a figure which shows another fixing method of the center part of a scanning lens. It is a figure which shows another example of the adjustment means of the z direction of the edge part of a scanning lens. It is a figure which shows another example of the adjustment means of the z direction of the edge part of a scanning lens. It is a figure which shows another example of the adjustment means of the z direction of the edge part of a scanning lens. 1 is a central sectional view showing an embodiment of an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical box 2 Scanning lens fixing | fixed part 3 Scanning lens 10 Leaf springs 11 and 12 Adjustment screw

Claims (11)

A light source that is modulated and driven based on an image signal, an optical deflection device that deflects a beam from the light source, a resin scanning lens that condenses the beam deflected by the optical deflection device on a surface to be scanned, and this scanning An optical box for holding the lens, and
A substantially central portion in the longitudinal direction of the scanning lens is fixed to the optical box,
An optical scanning device comprising an adjusting means for holding an end of the scanning lens in the longitudinal direction so as to be movable with at least one degree of freedom.   2. The optical scanning device according to claim 1, wherein a substantially central portion of the scanning lens in the longitudinal direction is fixed to the optical box by adhesion.   The optical scanning device according to claim 1, wherein an end of the scanning lens in the longitudinal direction is movable in the sub-scanning direction.   The optical scanning device according to claim 1, wherein an end portion of the scanning lens in a longitudinal direction is rotatable in a twisting direction.   5. The optical scanning device according to claim 4, wherein the width of the scanning lens in the sub-scanning direction is not uniform at the center and the end in the longitudinal direction of the scanning lens.   The optical scanning device according to claim 1, wherein the longitudinal end portion of the scanning lens is moved by at least one of a screw element, a linear motion element, and a pressure element.   2. The optical scanning device according to claim 1, wherein the moving direction of both ends of the scanning lens in the longitudinal direction by the adjusting means is a direction to be tuned.   The optical scanning device according to claim 1, wherein the moving directions of both ends in the longitudinal direction of the scanning lens by the adjusting means are opposite directions. A plurality of scanning lenses;
2. The optical scanning device according to claim 1, wherein each scanning lens is fixed so that beams reaching a central image height of a plurality of image carriers corresponding to each scanning lens substantially coincide with each other in the sub-scanning direction. An apparatus that performs optical writing from an optical writing device to an image carrier and forms an electrostatic latent image on the image carrier by electrophotography,
An image forming apparatus, wherein the optical writing device is the optical scanning device according to claim 1.   The image forming apparatus according to claim 10, wherein a plurality of optical writing devices are provided corresponding to each color.

Images