JP2004246329A - Multi-beam scanning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain high speed and high density recording and to realize a desired beam pitch in a market without adjustment in a short period of time. <P>SOLUTION: A multi-beam scanning device is provided with: a multi-beam light source device 100 in which the relative positions of a plurality of semiconductor laser arrays and a plurality of coupling lenses are adjusted and kept and integrally formed; a deflector which deflects a plurality of laser beams emitted from the coupling lenses; a scanning optical lens system which guides the beams emitted from the deflector onto a photoreceptor drum; and a housing which contains the deflector and the scanning optical lens system so that the relative position thereof are kept. The multi-beam scanning device is further provided with an adjustment member 104 inserted between the housing and the multi-beam light source device 100 and the beam pitch in the vertical scanning direction on the photoreceptor drum is adjusted by inserting the adjustment member 104. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a multi-beam scanning device that performs optical writing with a plurality of beams, and an image forming apparatus using the multi-beam scanning device.

  2. Description of the Related Art In image forming apparatuses such as laser printers, digital copiers, and facsimile machines, recently, higher recording speeds and higher recording densities have been required. In this case, if an attempt is made to increase the speed with a single-beam type beam scanning device, a deflector capable of rotating at a high speed will be used. Such a deflector is not only expensive, but also requires a soundproofing device for reducing noise caused by, for example, wind noise caused by high-speed rotation, leading to an increase in cost. Therefore, a multi-beam scanning device that simultaneously scans an image carrier such as a photoreceptor with a plurality of laser beams is adopted, and the recording speed is increased and the recording density is increased without performing high-speed rotation as in the above-described deflector. A so-called multi-beam scanning device for increasing the density is used.

  In such a multi-beam scanning apparatus, it is necessary to obtain a target beam pitch (scanning line interval) in terms of image quality. In particular, recently, in order to obtain high image quality, the density is increased, and a scanning line density of 1200 dpi or the like is required.

As a method of increasing the density to obtain high image quality, a method of rotating a plurality of light sources and a coupling lens about an axis perpendicular to the main scanning direction and the sub-scanning direction is known. Patent Document 1 discloses a configuration in which only a light source and a coupling lens are rotated, and an aperture for regulating a beam is not rotated with respect to a rotation axis. Switching and adjustment of a beam pitch in multi-beam scanning are disclosed. Therefore, the occurrence of deviation of the beam pitch due to the above is effectively reduced, and a good beam diameter is obtained.
JP 2001-13432 A

  In such a beam pitch adjusting method of Patent Literature 1, it is necessary to perform adjustment while being attached to the optical system housing. However, since the positional relationship between the light source and the coupling lens has been adjusted, if the light source fails and the image quality is significantly reduced, replace the holder with the adjusted positional relationship. It is necessary to adjust the beam pitch by using a beam, or to replace the entire multi-beam scanning device including the housing, the beam pitch of which has been adjusted. When replacing the entire multi-beam scanning device or adjusting the beam pitch, it takes time to perform the replacement or adjustment, and in many cases it is necessary to remove parts and units attached to the device for replacement. Are often shunned. From such a background, it is desired that a maintenance engineer in the market can easily replace the battery, and further, it is desired that no adjustment is made after the replacement.

  In addition, there has been a demand for visually ascertaining whether or not the beam pitch is correct after the replacement when no adjustment is performed in such a replacement operation.

  The present invention has been made in view of such circumstances of the prior art, and aims to achieve a higher recording speed and a higher recording density, and a high precision which is indispensable for forming high image quality. It is an object of the present invention to realize a high beam pitch in the market in a short time and without adjustment.

  Another object of the present invention is to make it possible to visually confirm the state of the beam pitch in the sub-scanning direction when the adjustment is realized without adjustment.

  In order to achieve the above object, a first means is a multi-beam light source device in which relative positions with respect to a plurality of semiconductor laser arrays and a coupling lens are adjusted and held, and is integrally formed, and is emitted from the coupling lens. A deflector for deflecting a plurality of laser beams, a scanning optical system for guiding a beam from the deflector onto a surface to be scanned, and a positional relationship between the deflector, the scanning optical system, and the multi-beam light source device. A multi-beam scanning device including a housing for accommodating the respective units, wherein the adjustment is performed between the housing and the multi-beam light source device to adjust a beam pitch in the sub-scanning direction on the surface to be scanned. It is characterized by having a member.

  The second means is characterized in that the plurality of semiconductor laser arrays in the first means are arranged such that a laser beam directed to the deflector has a predetermined opening angle.

  A third means is that the adjustment member in the first or second means has several kinds of thicknesses, and the thickness is determined according to an adjustment amount of a beam pitch in the sub-scanning direction on the surface to be scanned. It is characterized by the following.

  A fourth means is characterized in that several kinds of thicknesses of the adjusting member in the third means are identified by colors.

  A fifth means is characterized in that several thicknesses of the adjusting member in the third means are identified by their shapes.

  A sixth means is characterized in that the adjusting member in the first to fifth means is made of a film-like synthetic resin.

  A seventh means is characterized in that the adjusting member in the first to fifth means is made of a plate-like metal.

  Eighth means is characterized in that an adhesive is applied to one surface of the adjustment member in the first to seventh means.

  The ninth means is a multi-beam scanning device according to the first to eighth means, and the multi-beam scanning device optically scans the image carrier to form a latent image, and visualizes the formed latent image. An image forming apparatus is constituted by the image forming means.

  A tenth means is the image processing apparatus according to the ninth means, wherein the image forming / forming means visualizes the latent image by toner development and transfers the visualized toner image to a recording medium.

  The eleventh means is characterized in that, in the ninth or tenth means, a control means is provided in which a mode for visually confirming the state of the beam pitch with a visualized image is set. .

  A twelfth means is the image processing apparatus according to the eleventh means, wherein the control means writes a pair of two laser beams out of the plurality of laser beams at a predetermined interval in the main scanning direction. Is formed.

  According to a thirteenth aspect, in the twelfth aspect, the two predetermined laser beams are adjacent beams on the surface to be scanned.

  A fourteenth means is the thirteenth means, wherein the control means shifts the two laser beams of the preset pair one by one in the sub-scanning direction and shifts the predetermined interval in the main scanning direction. It is characterized by writing.

  Fifteenth means is the eleventh to fourteenth means, wherein the mode is such that the laser beam is deflected only on the same surface of the deflector and written on the surface to be scanned, And a second pattern written on the surface to be scanned by deflecting the laser beam on two adjacent surfaces.

  According to the present invention, a high recording speed and a high recording density are achieved, and a high-precision beam pitch that is indispensable for forming high image quality is realized in the market in a short time and without adjustment. I can do it.

  In addition, the state of the beam pitch in the sub-scanning direction can be visually confirmed as an image, so that the maintenance engineer can easily grasp the state of the beam pitch.

  Hereinafter, the best mode for carrying out the invention will be described with reference to the drawings.

  FIG. 6 is a diagram showing a schematic configuration of an entire digital copying machine as an image forming apparatus equipped with a multi-beam scanning device.

  The digital copying machine includes a copying machine main body 30, an automatic document feeder (hereinafter, referred to as “ADF”) 50, and a paper feeding unit 60. The ADF 50 automatically feeds the originals stacked on the original table 51 one by one and feeds the originals onto the contact glass 52 of the copying machine main body 30. After reading the image information by the scanner, the originals are transferred to the original discharge tray 53. Discharge up. Inside the copier body 30, there are a scanner unit 70 for reading image information of a document set on a contact glass 52 on the upper part thereof, a multi-beam scanning device 101 having a multi-beam light source device 100, and a latent image carrier. An image forming unit (corresponding to the reference numeral 76 in FIG. 7) having the photosensitive drum 8 and the like are provided. The scanner unit 70 has an optical scanning system including an exposure lamp, a plurality of mirrors, a lens, a CCD, and the like.

  Around the photosensitive drum 8 of the image forming unit 76, a charging device 31, a developing device 32, a transfer belt 33 forming a transfer unit, a cleaning device 34, and the like are arranged. A fixing device 55 is provided on the downstream side (in FIG. 6, on the left side) of the photoconductive drum 8 of the transfer sheet, and a reversing / discharging section 56 is provided on the downstream side. Below the fixing device 55, a duplex unit 40 is provided for reversing the transfer sheet and transporting it to the photosensitive drum 8 again when forming images on both sides of the transfer sheet.

  The optical scanning system of the scanner unit 70 optically scans the image of the original set on the contact glass 52, forms the image information on the light receiving surface of the CCD by a lens, and performs photoelectric conversion. The image signal (image information) is subjected to processing such as A / D conversion by an image processing circuit (not shown), and then various image processing is performed by an image processing unit 74 (FIG. 7). The multi-beam scanning device 101 writes an image based on the image signal on the charged surface of the photosensitive drum 8 whose surface is uniformly charged by the charging device 31 with a laser beam, thereby forming a latent image thereon. . When the photosensitive drum 8 rotates clockwise in FIG. 6 and moves to a certain position of the developing device 32, the latent image is developed by the developing device 32 to become a toner image (visible image).

  On the other hand, the transfer paper P stored in one of the tandem-type large-volume paper feeding device 61 and the universal trays 62 and 63 provided in the paper feeding unit 60 is transferred into the copying machine main body 30. Paper is fed toward. The transfer paper P is conveyed upward in the copying machine main body 30, and after its leading end abuts against the registration roller 54 and temporarily stops, the transfer paper P is accurately aligned with the toner image formed on the photosensitive drum 8. The toner image is re-conveyed by the registration roller 54 at the timing, and the toner image on the photosensitive drum 8 is transferred thereto.

  After the transfer paper is separated from the photosensitive drum 8, the transfer paper is conveyed to the fixing device 55 by the transfer belt 33, where the toner image is fixed by the fixing roller. Then, the transfer paper P after the fixing is conveyed in the straight-forward direction by the reversing / discharge unit 56 when one-sided image is formed, and is discharged onto the discharge tray 58 by the discharge rollers 57.

  When forming a double-sided image, the transfer paper P having an image formed on the front side is conveyed to the double-sided unit 40 in a state where the transfer paper P is turned upside down by the reversing / discharge unit 56, and the transfer paper P is fed again. The photosensitive drum 8 is again conveyed to the image forming section 76 provided with the photosensitive drum 8, and an image is formed on the rear surface side. Then, after the image is fixed by the fixing device 55, the image is conveyed in the rectilinear direction by the reversing / discharge unit 56 and is discharged onto the discharge tray 58 by the discharge roller 57.

  Although a photoconductive photoconductor is used for the photoconductor drum 8 as an image carrier, a silver halide photographic film may be used. In the case of a silver halide photographic film, a desired image can be obtained by developing a latent image by a multi-beam scanning device by a normal silver halide photographic process. Such an image forming apparatus can be specifically implemented as an optical plate making machine. Further, as the image carrier, a sheet-like material such as zinc oxide paper may be used, and in this case, the toner image can be fixed using the latent image carrier itself as a recording medium. Further, a toner image obtained by developing the electrostatic latent image formed on the latent image carrier can be transferred and fixed to a sheet-like recording medium (transfer paper, OHP sheet film, or the like). The latent image may be transferred to the sheet-shaped recording medium and then developed, and the obtained toner image may be fixed on the recording medium. The transfer of the toner image onto the sheet-shaped recording medium may be performed directly from the latent image carrier to the recording medium, or may be performed via an intermediate transfer medium such as an intermediate transfer belt.

  Next, the multi-beam scanning device 101 will be described with reference to FIG. FIG. 1 is a perspective view showing a multi-beam scanning device according to an embodiment of the present invention together with a photosensitive drum. In the present embodiment, an example in which eight beams are scanned is taken as an example, and two semiconductor laser arrays 1a and 1b each having four light emitting points are used for the light source unit 100. In the multi-beam scanning device 101, these semiconductor laser arrays 1a and 1b, coupling lenses 2a and 2b respectively coupling four light sources into one, and an opening for determining a beam spot shape are formed. A scanning optical lens including an aperture member 3, a cylinder lens 4 for focusing a beam in the sub-scanning direction, a deflector (polygon mirror) 5 having a plurality of deflecting / reflecting surfaces 5A formed on a peripheral surface thereof, an fθ lens, and the like. It is composed of a system 6, a mirror 7, and the like. The coupling lenses 2a and 2b couple divergent beams from a plurality of light sources, that is, form a beam form suitable for the subsequent optical system, for example, a parallel beam, a weak divergent beam, a weak convergent beam, and the like. The correspondence between the coupling lens and the light source may be one-to-one, or one coupling lens may couple beams from a plurality of light sources.

  Then, the respective laser beams emitted from the semiconductor laser arrays 1a and 1b are respectively coupled to the four light sources by the coupling lenses 2a and 2b corresponding to one coupling lens. After the coupled beams pass through the aperture member 3 and are regulated, the beams are focused in the sub-scanning direction by a cylinder lens 4 common to the beams. After being formed as a long linear image in the main scanning direction near the deflection reflecting surface 5A of the deflector 5, the light is reflected by the deflection reflecting surface 5A of the deflector 5. A plurality of line images corresponding to each laser beam are separated from each other in the sub-scanning direction.

  Each light beam reflected by the deflecting / reflecting surface 5A of the deflector 5 is deflected at a constant angular velocity as the deflector 5 rotates at a constant speed, and is constituted by a scanning optical lens system 6 (in the figure, a lens system such as an fθ lens). However, it can also be constituted by a concave mirror or the like), and is condensed as light spots separated from each other in the sub-scanning direction on the photosensitive drum 8 serving as an image carrier via the mirror 7, The drum 8 is scanned at a substantially constant speed. Although two semiconductor laser arrays are shown here as an example, the number of pairs of the semiconductor laser array as a light source and the number of coupling lenses can be increased to easily configure a larger number of beams.

  The principal rays of the light beams coupled by the coupling lenses 2a and 2b gradually approach the deflecting reflection surface 5A in the main scanning direction as shown in the figure, and intersect each other in the main scanning direction near the deflecting reflection surface 5A. . The angle θ formed by the coupled light beams from the intersection to the light source when viewed in the sub-scanning direction is referred to as the “open angle” between the light beams. As described above, by configuring the light source device such that the light beam directed to the deflector 5 has the opening angle θ, it is not necessary to use a conventional deflection combining element.

  Next, the configuration of the multi-beam light source device 100 and the vicinity thereof will be described with reference to FIGS. FIG. 3 is an exploded perspective view showing the configuration near the light source of the multi-beam scanning device, and FIG. 4 is a cross-sectional view showing the relationship between the light source and the coupling lens.

  Each of the semiconductor laser arrays 1a and 1b has a holding member 14 on the terminal side and a holder 13 on the light emitting unit side, and three holes 14a formed in the holding member 14 form three holes 14a formed in the holder 13. It is fixed by passing the screws 15 through the holes 13a. The holder 13 is attached to the lens holder 12 with three screws 16 respectively. On the other hand, the coupling lenses 2a and 2b are positioned on the lens holder 12 such that the side surfaces thereof are pressed by the leaf spring 10, and the upper and lower ends of the spring 10 are fixed to the lens holder 12 by screws 11.

  FIG. 4 shows the positional relationship between the semiconductor laser array and the coupling lens, and also shows a cross section of the lens holder 12, where the left-right direction is the main scanning direction, and the direction penetrating the front and back of the paper is the sub-scanning direction. Corresponding. Here, Aa and Ab are the optical axes of the respective light sources, Ba and Bb indicate the optical axis directions, and the coupling lens 10 can be adjusted and moved in the optical axis directions of Ba and Bb. Adjustment (focus adjustment). After the adjustment, it is fixed by the leaf spring 10 and the screw 11. On the other hand, the optical axis of the light source is adjusted by moving the holder 13 on which the semiconductor laser arrays 1a and 1b are fixed on the plane of the lens holder 12 in the directions of Ca, Cb, Da and Db, respectively. Here, Ca and Cb correspond to the main scanning direction, and Da and Db correspond to the sub-scanning direction. After the optical axis adjustment, the holder 13 is fixed to the lens holder 12 with the screw 16 inserted from the hole 12c of the lens holder 12, and the sub-assembly of the multi-beam light source device 100 is completed. Next, adjustment of the beam pitch of the multi-beam light source device will be described.

  Next, the arrangement of eight beams on the photosensitive drum 8 as an image carrier will be described with reference to FIG. Here, the left-right direction of the paper is scanned from left to right in the main scanning direction, and the up-down direction is scanned from bottom to top in the sub-scanning direction.

  B1, B3, B5, and B7 indicate beams (hatched circles) by one semiconductor laser array having four light emitting points, and B2, B4, B6, and B8 indicate beams by another semiconductor laser array having the same four light emitting points. The beams (white circles) are shown, and the beam arrangement in the sub-scanning direction is alternated in the order of B1, B2, B3,. The arrangement in the main scanning direction is an arrangement in which the odd-numbered beams B1, B3, B5, and B7 precede.

  Here, B1, B3, B5, B7 and B2, B4, B6, B8 are arranged on the photosensitive drum 8 at a distance of A in the main scanning direction. It is because it has. Since the interval between the light emitting points of the semiconductor laser array is accurately formed by a semiconductor process, the intervals P1 and P2 of the sub-scanning beams on the photosensitive drum 8 are determined by the lateral magnification of the optical system. In this embodiment, the beam intervals P1 and P2 are the same, and a half of P1 and P2 is the desired recording density interval P. P1 and P2 are 42.3 μm and correspond to a beam interval having a density of 600 dpi, and P corresponds to a double density of 1200 dpi and is 21.2 μm.

  Next, specific adjustment of the recording density interval P (beam pitch) of the multi-beam light source device 100 will be described with reference to FIG. The sub-assembly and the bracket 17 after the adjustment of the optical axis and the coupling are fitted into the cylindrical projection 12a provided on the lens holder 12 and the hole 17a provided on the bracket 17, and can be rotated around the hole 17a. It has become. The laser beam that has passed through the coupling lenses 2a and 2b travels through the hole 17b of the bracket 17 toward the aperture 3 (FIG. 1). The lens holder 12 and the bracket 17 are fixed by inserting screws 18 from the four holes 17g of the bracket 17 to the four holes 12d of the lens holder 12, respectively, after adjusting the beam pitch described later. The center of rotation between the lens holder 12 and the bracket 17 in FIG. 3 corresponds to the point E in FIG. When the beam is rotated about the hole 17a as described above, the eight beams on the photosensitive drum 8 rotate about the point E in the same manner. At this time, by performing fine rotation adjustment, the relative position between the odd-numbered beam (shaded circle) and the even-numbered beam (white circle) changes, and the recording density interval P (beam pitch) can be adjusted.

  The bracket 17 is provided with two reference surfaces 17c as positioning references in the sub-scanning direction, a positioning hole 17d as a positioning reference in the main scanning and optical axis directions, and an elongated hole 17e in the main scanning direction. This is a reference for each of the sub-scanning, the main scanning, and the direction corresponding to the optical axis when the multi-beam light source device 100 is mounted on the housing 102 as the multi-beam scanning device 101 or when the multi-beam light source device 100 is mounted on the adjustment jig during factory adjustment. The housing 102 holds a positional relationship with the deflector 5, the scanning optical lens system 6, and the multi-beam light source device 100, and is made of a metal such as aluminum die-cast, a molded product such as a synthetic resin, or a metal / resin. Made from composite materials. The adjustment of the beam pitch at the factory corresponds to the position on the photosensitive drum 8 using a scanning optical system and a deflector having the same configuration as the multi-beam scanning device 101 after being positioned on an adjustment jig (not shown). A beam pitch is measured by disposing a CCD camera or the like at the position.

  On the other hand, an adjustment arm 12b is provided at one end of the lens holder 12 of the multi-beam light source device 100 so as to project from an end face in a short direction parallel to the longitudinal direction of the lens holder 12 and perpendicular to the longitudinal direction. . The adjustment arm 12b is connected to an adjustment jig and can be moved by a very small amount in the direction corresponding to the sub-scan. Since the adjustment arm 12b is separated from the center of rotation, the slight movement in the sub-scanning corresponding direction is leveraged to enable the minute rotation. When a desired beam pitch is obtained, the beam is fastened and fixed with the four screws 18 described above. Thereafter, the screws 20 are respectively inserted into the two holes 19a provided in the control board 19 and fastened and fixed to the control board 19, and the semiconductor laser arrays 1a and 1b are electrically connected to the control board 19 by soldering or the like. And the multi-beam light source device 100 is completed. By performing adjustment using the adjustment jig as described above, not only the optical axis and the coupling but also the beam pitch can be adjusted within a fixed reference variation range as the multi-beam light source device 100, and the unit is completed as one unit. The quality as maintenance parts on the market can be kept uniform.

  However, when the multi-beam scanning device 101 is assembled in a factory, when the multi-beam light source device 100, the scanning optical system, the deflector 5, and the like are combined with the housing 102 such as an optical housing, the above-mentioned beam pitch may be shifted. As a cause of the occurrence, the reference surface of the casing 102 (see FIG. 5), particularly the reference surface with the multi-beam light source device 100, and the reference surface with the cylinder lens 4 are not exactly the same due to variations in the adjustment jig and processing accuracy. That's why. In addition, since the lens is not the same as the cylinder lens 4 used for the adjustment jig, the lens itself may have an optical axis inclination from the reference plane, and this difference is also shifted. Since the multi-beam light source device is adjusted using the adjustment jig, any light source device shows the same tendency. As a countermeasure, although the degree is reduced by increasing the processing accuracy of the housing and the cylinder lens, the yield is reduced by a sorting operation or the like, and the cost is greatly increased. Therefore, the present embodiment solves the problem as follows.

  This solution will be described with reference to FIG. FIG. 5 is a perspective view showing a state where the multi-beam light source device 100 is positioned and fixed to the housing 102.

  The multi-beam light source device 100 and the housing 102 are provided with positioning holes of the multi-beam light source device 100 in the sub-scanning corresponding direction by two reference surfaces 17c of the multi-beam light source device 100 and two reference surfaces 102a of the housing 102. At 17d, the slot 17e in the main scanning direction and the two reference pins 102b of the housing 102 are positioned in the main scanning corresponding direction and the optical axis direction, and are fastened and fixed by two screws 103 by the mounting holes 17f. Here, by inserting the adjusting member 104 between any one of the two reference surfaces 17c of the multi-beam light source device 100 and the two reference surfaces 102a of the housing 102, the multi-beam light source device has a small angle. You will lean. In other words, the beam is tilted by a small angle around the point E in FIG. 2, and as a result, the beam pitch can be finely adjusted. Since there are two reference planes, the place where the adjustment member 104 is inserted in accordance with the beam pitch correction direction is clear. Further, since the position of the reference surface in the main scanning direction is also invariable, the thickness of the inserted adjustment member and the correction amount of the beam pitch are in a proportional relationship. Therefore, at the time of factory assembly adjustment, by measuring the beam pitch at a location corresponding to the surface of the photosensitive drum 8 of the assembled multi-beam scanning device 101, the correction amount and the correction direction from the target beam pitch are clearly defined. Become. For example, if the correction amount and the correction direction are incorporated in a measurement routine, labor saving and man-hour reduction can be expected. By preparing several types of adjusting members 104 having different thicknesses, the beam pitch can be corrected more accurately.

  In this embodiment, four types of the adjusting members 104 are used at 25 μm intervals, that is, 25 μm, 50 μm, 75 μm, and 100 μm. Of course, these may be used one by one or a plurality of sheets may be used. It was confirmed that a fine correction of a beam pitch of 1.5 μm was possible with only 25 μm, and a correction of 12 μm with a beam pitch of 200 μm.

  In addition, the use of several types is visually easy to understand if there is a distinction in the appearance of the adjustment member 104. In this embodiment, the color of the adjustment member is changed according to the thickness of the adjustment member. 25 μm is brown, 50 μm is transparent, 75 μm is black, and 100 μm is milky white. There is also a method of identifying not only the color but also the shape of the adjustment member with a difference, for example, a method of cutting a corner or making a cut in a part of the shape. The material of the adjustment member 104 is desirably a film-like synthetic resin such as PET or a metal such as a stainless steel strip. Particularly, the film-shaped synthetic resin can be supplied at a low cost.

  In addition, when the adhesive is applied to one surface of the adjustment member 104, the adjustment member 104 can be attached to the housing 102 with the adhesive surface facing the housing 102 to be integrated. In this case, since the adjusting member is not merely sandwiched therebetween, the adjusting member does not separate from the housing 102 when attaching or detaching the light source device, and there is no fear of loss.

  When the adjustment member adjusts the beam pitch, the adjustment member performs relative correction of the housing with respect to the multi-beam light source device. If the multi-beam light source device adjusted by the adjustment jig is used, when the light source device is replaced, the same beam pitch as before the replacement can be obtained by inserting the same type of adjustment member into the same place as before the replacement. Can be. As a result, a desired beam pitch can be obtained in a short time without any adjustment.

  The image forming apparatus according to the present embodiment has a mode in which the state of the beam pitch in the sub-scanning direction is output as an image image for visually observing the beam pitch. Can be visually observed.

  FIG. 7 is a block diagram schematically illustrating a control circuit of the image forming apparatus according to the present embodiment. In the figure, a system control unit 71 controls an ADF 50, a multi-beam scanning unit (apparatus) 101, an image forming unit 76, a fixing unit 55, a paper feeding unit 60, and a scanner unit 70. The memory 73, the image processing unit 74, and the nonvolatile memory 75 are connected to the system control unit 71, respectively. The system control unit 71 executes a control desired by the user in response to an instruction input from the operation display unit 72, temporarily stores the image data read by the scanner unit 70 in the image memory 73, and then executes a predetermined or desired operation. The image processing section 74 performs image processing, outputs the processed image to the multi-beam scanning section 101, forms an image in the image forming section 76, transfers the image to the transfer sheet P fed from the sheet feeding section 60, fixes the sheet, and fixes the sheet. The sheet is discharged from the roller 57. These control programs are stored in the non-volatile memory 75, and the system control unit 71 executes predetermined control according to the control programs.

  In this system, a mode in which the state of the beam pitch in the sub-scanning direction is output as an image for visually observing is set. When this mode is selected from the operation display unit 72, FIG. 8A or FIG. Is output. FIG. 8 is an image image in which the state of the beam pitch in the sub-scanning direction can be visually observed. The conveying direction in the figure indicates the conveying direction of the transfer paper P on which this image is printed, and the multi-beam scanning device. In the sub-scanning direction.

  The image of the pattern 1 shown in FIG. 8 is a case of eight beams, and each beam is 0ch, 1ch, 2ch... 7ch in the sub-scanning direction (B1, B2, B3, B4, B5 in FIG. 2). B6, B7, and B8). The pattern is printed at a recording density of 1200 dpi using three beams of 0ch, 1ch, and 2ch. As shown in FIG. 8A, 256 dots are printed in the main scanning direction on a pair of 0ch and 1ch (B1, B2). The next 256 dots in the main scanning direction are printed in pairs of 1ch and 2ch (B2, B3), and this pattern is repeated in the main scanning direction. This is printed as one block in the same block at intervals of 32 dots in the sub-scanning direction.

  Paying attention to printing in the main scanning direction, two beams adjacent in the sub-scanning direction are constantly printed. If the beam pitch in the sub-scanning direction is constant, that is, if the pitch between channels 0 to 1 and the pitch between channels 1 and 2 are constant, the line widths printed by the adjacent beams are the same, so that the channels 0 to 1 are visually recognized. There is no density difference between the pitches between 1 ch and the pitch between 1 ch and 2 ch, and a uniform pattern can be observed. However, if the intervals are different between the pitches of 0ch to 1ch and the pitches of 1ch and 2ch, the line widths printed by the adjacent beams will be different, so that the pattern is observed as a pattern having a density difference in the main scanning direction. . That is, the state of the recording density interval P shown in FIG. 2 can be visually observed. In this embodiment, the pattern is formed with 256 dots in the main scanning direction and 32 dots in the sub-scanning direction. However, an image may be formed at an easily observable pattern interval due to the difference in recording density, the configuration of the optical system, and the configuration of the image forming apparatus. .

  The pattern 2 shown in FIG. 8B is the same as the pattern 1 described above, but the paired beams are different. That is, in pattern 2, three beams of 6ch, 7ch, and 0ch (B7, B8, B1) form a pair of 6ch and 7ch (B7 and B8) and a pair of 7ch and 0ch (B8 and B1). Here, as can be seen from FIG. 2, 0ch is a beam B1 located next to B8 in the sub-scanning direction, and the next adjacent beam different from the deflecting surface of the deflector (polygon mirror) 5 forming a pair of 6ch and 7ch. It is formed by a deflecting surface. That is, the pattern 1 is printed from two deflecting surfaces while the deflecting surface of the deflector 5 is only the same surface. Therefore, the pattern 2 includes an inter-surface error such as a tilt of the deflection surface of the deflector 5 and a radius of an inscribed circle, so that the overall characteristics of the multi-beam scanning device 102 can be visualized. Therefore, the maintenance engineer and the factory adjuster can adjust the beam pitch by using the adjusting member as described above while viewing the pattern output in this manner.

  The printing of the patterns 1 and 2 shown in FIG. 8 may be set in a special mode used by a maintenance engineer or a factory coordinator for adjustment in distinction from the normal mode. For example, a setting can be made so that the mode can be shifted to the mode shown in FIG. 8 by inputting a password and a mode number from the operation display unit 72 using, for example, ten keys. The mode is set in a control program, and a CPU (not shown) of the system control unit 71 controls the multi-beam scanning device according to the control program to perform a writing operation as shown in FIG.

  Further, according to the present embodiment, since a beam scanning device which can obtain a target beam pitch in a short time and without adjustment is used, high-speed and good image formation can be performed.

1 is a perspective view showing a multi-beam scanning device according to one embodiment of the present invention together with a photosensitive drum. FIG. 3 is a schematic diagram of an arrangement of eight beams on a photosensitive drum. FIG. 2 is an exploded perspective view illustrating a configuration near a light source of the multi-beam scanning device. FIG. 3 is a cross-sectional view illustrating a relationship between a light source and a coupling lens. It is a perspective view showing the state where a multi-beam light source device is positioned and fixed to a housing. FIG. 1 is an overall configuration diagram illustrating an example of a digital copier equipped with a multi-beam scanning device. FIG. 2 is a block diagram schematically illustrating a control circuit of the image forming apparatus according to the embodiment of the present invention. FIG. 7 is a diagram illustrating an image image in which a state of a beam pitch in a sub-scanning direction can be visually observed.

Explanation of reference numerals

1a, 1b Semiconductor laser array 2a, 2b Coupling lens 3 Aperture member 4 Cylinder lens 5 Deflector (polygon mirror)
Reference Signs List 6 scanning optical lens system 8 photosensitive drum 12 lens holder 12b adjusting arm 13 holder 17 bracket 17c reference surface 17d positioning hole 17e long hole 19 control board 30 copier body 50 automatic document feeder (ADF)
Reference Signs List 60 Paper feed unit 70 Scanner unit 72 Operation display unit 73 Image memory 74 Image processing unit 75 Non-volatile memory 100 Multi-beam light source device 101 Multi-beam scanning device (unit)
102 Housing 102a Reference surface 102b Reference pin 104 Adjusting member

Claims (15)

A multi-beam light source device integrally formed by adjusting and holding relative positions of a plurality of semiconductor laser arrays and a coupling lens; a deflector for deflecting a plurality of laser beams emitted from the coupling lens; A scanning optical system for guiding a beam from a scanner onto a surface to be scanned; In the beam scanning device,
A multi-beam scanning device, comprising: an adjusting member inserted between the housing and the multi-beam light source device to adjust a beam pitch in the sub-scanning direction on the surface to be scanned.   2. The multi-beam scanning device according to claim 1, wherein the plurality of semiconductor laser arrays are arranged such that a laser beam directed to the deflector has a predetermined opening angle. 3.   The adjustment member includes a plurality of members having a plurality of types of thicknesses, and the member having the thickness is selected according to an adjustment amount of a beam pitch in the sub-scanning direction on the surface to be scanned. Item 3. The multi-beam scanning device according to item 1 or 2.   4. The multi-beam scanning device according to claim 3, wherein different colors are respectively provided to the plurality of types of adjustment members, and the thickness of the adjustment members is identified by the colors.   The multi-beam scanning apparatus according to claim 3, wherein the plurality of types of adjustment members are set to different shapes, and the thickness of the adjustment members is identified by the shape.   The multi-beam scanning device according to claim 1, wherein the adjustment member is made of a film-shaped synthetic resin material.   The multi-beam scanning device according to claim 1, wherein the adjustment member is made of a plate-shaped metal.   The multi-beam scanning device according to claim 1, wherein an adhesive is applied to one surface of the adjustment member. A multi-beam scanning device according to any one of claims 1 to 8,
Image forming means for optically scanning the image carrier by the multi-beam scanning device to form a latent image, and visualizing the formed latent image;
An image forming apparatus comprising:   10. The image forming apparatus according to claim 9, wherein the image forming unit visualizes the latent image by developing the toner and transfers the visualized toner image to a recording medium.   The image forming apparatus according to claim 9, further comprising a control unit configured to set a mode for visually confirming the state of the beam pitch with a visualized image.   12. The image forming apparatus according to claim 11, wherein the control unit writes an image of two laser beams of the plurality of laser beams as a pair at a predetermined interval in the main scanning direction. Image forming apparatus.   13. The image forming apparatus according to claim 12, wherein the two predetermined laser beams are adjacent beams on the surface to be scanned.   14. The method according to claim 13, wherein the control unit writes the two pairs of laser beams in the sub-scanning direction one by one in the sub-scanning direction and writes the laser beams in the main-scanning direction at the predetermined interval. Image forming device. The mode includes a first pattern for deflecting the laser beam only on the same surface of the deflector and writing the laser beam on the surface to be scanned, and a second pattern for deflecting the laser beam on two adjacent surfaces of the deflector to scan the surface. The image forming apparatus according to claim 11, further comprising: a second pattern to be written on the image.

Images