JP2009109551A - Optical scanner and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner, capable of accurately deflecting and scanning a plurality of beams, while reducing the manufacturing cost using a compact configuration, and to provide an image forming apparatus equipped with the optical scanner. <P>SOLUTION: The optical scanner comprises a plurality of semiconductor lasers 41 which emit beams; an optical deflection unit 1 which deflects the beams; a plurality of imaging members which image the deflected beams onto the surface of a photoreceptor drum 32, and the optical deflection unit 1 has a first deflection element 3u and a second deflection element 3d, on which a deflection face is formed; a driving element 4 which receives driving force; and an actuator 9 which drives the driving element 4 where the first deflection element 3u, the second deflection element 3d and the driving element 4 are connected in series by torsion springs 5, and 6 and the first deflection element 3u and the second deflection element 3d are rocked about the rocking axis O of the torsion springs 5 and 6, when the driving element 4 rocks. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical scanning apparatus that performs optical writing using a laser beam in an image forming apparatus such as an LBP, a digital copying machine, or a digital FAX, and an image forming apparatus including the optical scanning apparatus.

  In recent years, colorization of image forming apparatuses has progressed, and so-called tandem image forming apparatuses that can perform high-speed printing at the same speed as monochrome are widely known. The tandem method is a method in which an optical scanning system is provided for each color, and a desired image is obtained by superimposing images formed in the respective optical scanning systems.

  Many types of image forming apparatuses having such a tandem method have been proposed which include a common rotary polygon mirror for a plurality of optical scanning systems. Among them, there have been proposed ones in which a rotating polygon mirror used as an optical deflection unit is replaced with a single mirror that vibrates sinusoidally (Patent Documents 1 and 2).

  Patent Document 1 describes a configuration in which a beam for four colors is deflected and scanned on one side of a vibrating mirror, and the scanned beam is separated for each color and guided to each photoconductor. Has been.

  Further, in Patent Document 2, deflection scanning is performed using both surfaces of a vibrating single mirror (or a two-piece laminated mirror), and the scanned beam is separated for each color to correspond to each corresponding photosensor. A configuration for guiding light to the body is described. That is, by scanning the beam for two colors on one side of the mirror, the beam for a total of four colors is deflected and scanned on both sides.

Furthermore, in Patent Document 2, not only a type using a double-sided mirror, but also mirrors with independent single-sided mirror surfaces are pivotally supported by separate rocking shafts and arranged so that the opposite mirror surfaces face each other. The configuration to be performed is also described.
JP 2006-243034 A JP 2006-292891 A

  However, the conventional optical scanning device and the image forming apparatus including the same cause the following problems.

  In the above-described conventional optical scanning device, the mirror provided on the swing shaft is a single sheet (or a mirror that is a two-piece laminated body). Therefore, in order to make a beam accurately incident on a single mirror from a plurality of light sources, there is a design restriction in terms of how to arrange incident members such as mirrors and lenses in a narrow space. It was.

  For example, Patent Document 1 and Patent Document 2 describe a configuration in which beams emitted from a plurality of light sources are combined using a half mirror or the like and incident on one vibrating mirror. However, the half mirror is generally expensive, and the half mirror needs to be positioned with high accuracy on the optical path. As a result, the manufacturing cost increases.

A configuration is also known in which the deflection points on one mirror surface that vibrates are aligned by inclining and arranging the members of the incident system. As the direction in which the incident system member is tilted, there are a case where it is tilted in the main scanning direction and a case where it is tilted in the sub-scanning direction.

  However, in the case where incident members are arranged side by side in the main scanning direction, the beams emitted from the plurality of light sources are all deflected in different directions when the oscillating mirror is stationary. That is, there arises a problem that the scanning center is different.

  In addition, if the speed of the beam deflected and scanned by one mirror that vibrates sinusoidally is the same speed on the photosensitive member, the scanning lens needs to have, for example, f · arcsin θ characteristics. However, since the phases of the sine waves of all four colors are different, it is difficult to make the beams of all four colors have the same speed.

  In addition, when deflecting and scanning a beam with a single vibrating mirror, so-called vignetting occurs in which the luminous flux of the incident beam deviates from the mirror surface at the scanning end of the mirror unless the mirror size is increased in the main scanning direction. To do. When vignetting occurs, the spots on the photoreceptor are enlarged, and image defects may occur.

  On the other hand, when the incident members are arranged side by side in the sub-scanning direction, if the beam scanned by the mirror is directly guided to the photosensitive member, it is tilted with respect to a plane perpendicular to the swing axis of the mirror. The beam will have a larger scan line bend.

  That is, a large scanning line bend is caused according to each color, and the printing position is different for each color on the image, so that color misregistration occurs. In order to prevent the occurrence of such color misregistration, there is a method of correcting the scanning line curve with the scanning lens. However, if the correction amount is too large, the imaging performance may be deteriorated and an image defect may occur.

  In addition, when both surfaces of the scanning mirror are used as in Patent Document 2, since the incident system beam for one surface is sufficient for two colors, the occurrence of color shift is reduced by that amount, but the effect is not eliminated.

  Further, if the tilt angle in the sub-scanning direction is narrowed, the beam pitch becomes narrow in the arrangement of the incident system, so that the beams may interfere with each other. On the other hand, if the tilt angle is too narrow, the beam pitch is too narrow and it becomes difficult to separate the light beams. In order to narrow the beam pitch of the incident system, there is a method using a semiconductor laser having a plurality of light emitting points, but the beam separation becomes more difficult.

  Also, there is a method of widening the sub-scanning pitch of the incident system by shifting the mirror reflection point for each beam in the sub-scanning direction (the swinging axis direction of the oscillating mirror). Will become bigger.

  Here, a problem that occurs when the mirror size increases will be described.

The resonance frequency of the mirror is expressed by the following equation.

  In the above equation, f is the resonance frequency, K is the spring constant of the beam supporting the mirror, and I is the moment of inertia of the mirror. As the mirror size increases, the moment of inertia I increases, so the resonance frequency f decreases from the above equation.

  When the resonance frequency f is reduced, the writing speed of the image forming apparatus is reduced and it is necessary to take measures such as lowering the resolution. Therefore, in order to maintain the resonance frequency f at the original value, it is necessary to increase the spring constant K. is there.

  The spring constant K can be increased by increasing the cross-sectional area of the torsion spring that supports the scanning mirror. However, if the cross-sectional area of the torsion spring is increased, the stress applied to the spring at the maximum torsion increases and the torsion spring breaks. There is a fear.

  Therefore, in order to increase the spring constant without increasing the stress applied to the spring at the maximum torsion, it is conceivable to lengthen the torsion spring. However, if the torsion spring is lengthened, the optical scanning device becomes larger in the swing axis direction. This causes a problem.

  As described above, in the case of providing one mirror that vibrates with respect to the swing axis, it is necessary to position the incident system with high accuracy in a limited space, resulting in an increase in manufacturing cost (Patent Document) 1, Patent Document 2). Further, in order to arrange the incident system in a limited space, even when a method of tilting the incident system in the main scanning direction or in the sub-scanning direction is employed, an image defect occurs, and the optical scanning device This causes the problem of increasing the size.

  In view of these circumstances, the present invention provides an optical scanning apparatus capable of accurately deflecting and scanning a plurality of beams while reducing the manufacturing cost with a compact configuration, and an image forming apparatus including the optical scanning apparatus. Objective.

  In order to achieve the above object, in the present invention, a plurality of light sources that emit beams, a light deflection unit that deflects the beams emitted from the plurality of light sources, and a beam deflected by the light deflection unit are provided. And a plurality of imaging members that form an image on the surface of the photoconductor corresponding to the beam. The optical deflection unit includes a first deflector having a beam deflection surface formed on the surface, and a first deflector. The first deflector, the second deflector, and the driver are connected in series by a torsion spring. The first deflector and the second deflector are configured to be swingable about a swing shaft of the torsion spring by being connected and driving the driver by the drive means. To do.

  Also, a plurality of light sources that emit beams, a light deflection unit that deflects the beams emitted from the plurality of light sources, and an image of the beams deflected by the light deflection unit on the surface of the photosensitive member corresponding to the beams An optical scanning device comprising: a plurality of imaging members, wherein the optical deflection unit includes a first deflector, a second deflector, a third deflector having a beam deflection surface formed on a surface thereof; and A first deflector, a second deflector, a third deflector, a fourth deflector, a driver that receives a driving force, and a driving unit that drives the driver. The deflector and the driver are connected in series by a torsion spring, and the driving means drives the driver so that the first deflector, the second deflector, the third deflector, and The fourth deflector can swing around the swing axis of the torsion spring. Characterized in that it is configured to.

  In the image forming apparatus of the present invention, the optical scanning device described above, a plurality of photosensitive members on which a beam deflected from the optical scanning device is imaged, and the photosensitive member are formed. And a transfer means for transferring the transferred image onto the sheet material.

According to the present invention, it is possible to provide an optical scanning apparatus capable of accurately deflecting and scanning a plurality of beams and an image forming apparatus including the same while reducing the manufacturing cost with a compact configuration.

  The best mode for carrying out the present invention will be exemplarily described in detail below based on the embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

[First Embodiment]
With reference to FIGS. 1 to 6, an optical scanning device and an image forming apparatus including the same according to a first embodiment of the present invention will be described.

(Overall configuration of image forming apparatus)
First, the overall configuration of the image forming apparatus according to the present embodiment will be described. FIG. 6 shows a schematic configuration of the image forming apparatus according to the present embodiment.

  When image formation is performed, beams Lc, Lm, Ly, and Lk that are light-modulated based on image information are emitted from the optical box 31, and the corresponding photosensitive drums (photoconductors) 32c, 32m, 32y, and 32k are respectively output. Irradiated on the surface.

  The surface of each photosensitive drum is uniformly charged in advance by primary chargers 33c, 33m, 33y, and 33k, and the surface of each photosensitive drum is irradiated with the beams Lc, Lm, Ly, and Lk. An electrostatic latent image is formed.

  To the electrostatic latent images formed on the surfaces of the photosensitive drums 32c, 32m, 32y, and 32k, cyan, magenta, yellow, and black toners are supplied from the developing units 34c, 34m, 34y, and 34k, and the electrostatic latent images are supplied. Is visualized as a toner image.

  The toner image is conveyed to a position on the transfer belt 39 as the photosensitive drum 32 rotates. The transfer belt 39 (transfer means) conveys the sheet material 36 and transfers the toner image formed on the surface of each photosensitive drum 32 to the photosensitive drum 32 in accordance with the timing at which the toner image is conveyed to a position on the transfer belt 39. The sheet material 36 is conveyed to the nip of the belt 39.

  As a result, cyan, magenta, yellow, and black toner images are sequentially superimposed and transferred onto the sheet material 36 to form a desired color image on the sheet material. Note that the drive roller 40 that drives the transfer belt 39 is connected to a drive motor (not shown) with small rotation unevenness in order to feed the transfer belt 39 with high accuracy.

  The color image formed on the sheet material 36 is heat-fixed by a fixing device 37 and then conveyed by a discharge roller 38 to be output to the outside of the image forming apparatus.

(Overall configuration of optical scanning device)
With reference to FIG. 5, the overall configuration of the optical scanning device according to the present embodiment will be described. FIG. 5 is a perspective view showing the overall configuration of the optical scanning device according to the present embodiment.

As shown in FIG. 5, the optical scanning device according to the present embodiment includes a plurality of semiconductor lasers 41c, 41m, 41y, and 41k that emit beams, and an optical deflection unit 1 that deflects and scans the emitted beams. In addition, fθ lenses 44 cm and 44 yk that transmit the deflection-scanned beam and first to third reflection mirrors that reflect the beam are provided. The fθ lens and the first to third reflection mirrors are provided as an imaging member that forms an image of the beam on the surface of the photosensitive drum. And these image formation member and the light deflection unit 1 are accommodated integrally in an optical box (not shown).

  With the above configuration, when a beam is imaged on the surface of the photosensitive drums 32c, 32m, 32y, and 32k provided corresponding to each beam, first, the semiconductor lasers (light sources) 41c, 41m, and 41y are based on the image information. , 41k.

  A total of four emitted beams are deflected and scanned by the optical deflection unit 1 in two different directions. The deflected and scanned beams pass through the fθ lenses 44 cm and 44 yk, respectively.

  For example, out of the two beams transmitted through the fθ lens 44 cm, the beam emitted from the semiconductor laser 41 c is reflected by the first reflecting mirror 45 c and forms an image on the photosensitive drum 32 c as a beam Lc.

  On the other hand, the beam emitted from the semiconductor laser 41m is sequentially reflected by the second reflecting mirror 46m and the third reflecting mirror 47m, and forms an image on the photosensitive drum 32m as a beam Lm.

  Similarly, of the two beams transmitted through the fθ lens 44yk, the beam emitted from the semiconductor laser 41k is reflected by the first reflecting mirror 45k and forms an image on the photosensitive drum 32k as a beam Lk.

  The beam emitted from the semiconductor laser 41y is sequentially reflected by the second reflecting mirror 46y and the third reflecting mirror 47y, and forms an image on the photosensitive drum 32y as a beam Ly.

  The process from when these four beams are emitted from the semiconductor laser 41 until the image is formed on the photosensitive drum 32 will be described in more detail.

  Beams emitted from the semiconductor lasers 41c, 41m, 41y, and 41k are converted into parallel light (collimated light) by the collimator lenses 42c, 42m, 42y, and 42k. The collimated light passes through the cylindrical lenses 43c, 43m, 43y, and 43k and enters the light deflection unit 1.

  The configuration of the optical deflection unit 1 will be described later. In the optical deflection unit 1 according to the present embodiment, three movable elements are swingably provided on a hollow plate member 2 via a torsion spring. The mover is configured to play a role of deflecting the beam as a deflector. In the following description, the movable element that deflects the beam is referred to as a deflector.

  When a beam is incident on a deflector provided in the optical deflection unit 1, the incident beam is compressed in the sub-scanning direction on the deflecting surface on the deflector to form a line image. In the present embodiment, the deflecting surfaces are formed on both the front and back surfaces of the deflector.

  The deflection surfaces on the front and back sides of these deflectors and the surfaces of the photosensitive drums 32c, 32m, 32y, and 32k corresponding to the respective deflection surfaces are configured so as to be conjugate with each other in the sub-scanning direction. Therefore, it is possible to reduce the so-called surface tilt in the sub-scanning direction beam position on the surface of the photosensitive drum 32 due to the deflection surface tilt error.

Also, the four beams emitted from the semiconductor laser 41 are scanned as optimally narrowed beams on the corresponding photosensitive drums 32c, 32m, 32y, and 32k, respectively, so that the fθ lenses 44cm and 44yk are scanned. It is adjusted by.

  Further, in the present embodiment, the beam deflected by one of the deflectors is configured to be able to be detected by the BD sensors 48m and 48y. According to this configuration, it is possible to synchronize the writing signal for each scanning time based on the output signals from the BD sensors 48m and 48y, and to prevent the writing position deviation of the beam.

  The BD sensors 48m and 48y are provided at both ends of the optical scanning device, and are used to control the scanning amplitude, the scanning cycle, and the like of the deflector using the beam incident timing.

(Configuration of light deflection unit)
With reference to FIGS. 1-4, the structure of the optical deflection | deviation unit 1 with which the optical scanning device based on this Embodiment is equipped, and its effect | action are demonstrated.

  FIG. 3 is a perspective view showing the overall configuration of the light deflection unit 1. FIG. 3A shows a state seen from the front side, and FIG. 3B shows a state seen from the back side. FIG. 4 is an exploded perspective view of the light deflection unit 1. FIG. 4A shows a state seen from the front side, and FIG. 4B shows a state seen from the back side.

  As shown in FIGS. 3 and 4, the end of the torsion spring that connects the three movers so as to be swingable is held on the inner peripheral side of the plate member 2 surrounding the torsion spring. Furthermore, the plate member 2 and the actuator 9 (driving means) for driving the mover are integrally held by the holder 8 (holding member).

  The light deflection unit 1 having these components is screw-fixed to the optical box 31 (FIG. 6) through the screw holes 12. Further, as shown in FIG. 3, beams L2u and L2d irradiated from the back side are incident on the plate member 2 through openings 13u and 13d provided in the holder 8, and are deflected and scanned.

  As shown in FIG. 4, the actuator 9 of the light deflection unit 1 uses an iron core (core) 10 around a winding (coil) 11. The actuator 9 is inserted into a recess 14 provided in the holder 8, and is firmly fixed to the holder 8 by press-fitting the rear end of the iron core (core) 10 into the insertion port 15 of the holder 8. After the actuator 9 is assembled in this way, the plate member 2 is assembled from the front side.

  One of the movers provided on the plate member 2 is driven by energizing the winding (coil) 11. Although the configuration of the plate member 2 will be described later, the plate member 2 is provided with a permanent magnet 7 in one of the movers connected in series by a torsion spring, and this mover is used to swing the torsion spring. It is used as a driver that swings another mover around the moving axis O. Hereinafter, the mover that receives the driving force from the actuator 9 and causes the other mover to swing around the swing axis of the torsion spring will be referred to as a driver.

  When the winding (coil) 11 is energized, a Lorentz force is generated between the winding (coil) 11 and the permanent magnet (magnet) 7 to act as a torque for swinging the driver, and accordingly, the torsion spring The deflector connected in series swings.

  Further, by modulating the current applied to the winding (coil) 11, it is possible to cause the driver and the deflector to oscillate around the oscillation axis of the torsion spring. Thus, the two deflectors can deflect and scan the beam incident on the optical deflection unit 1.

  Further, by arranging a driver element between the two deflectors, the two deflectors are arranged at a distance that is more than the size of the actuator 9, and the actuator 9 transmits the beam deflected by the deflector. The possibility of shading is low.

  Next, the configuration of the plate member 2 including one driver and two deflectors will be described with reference to FIG. FIG. 1 is a perspective view showing the overall configuration of the plate member in the present embodiment.

  The plate member 2 is manufactured by etching a Si single crystal wafer. As described above, the plate member 2 includes the deflectors 3u and 3d and the driver 4, which are connected in series by the torsion springs 6u, 5u, 5d, and 6d.

  Further, a rod-like permanent magnet (magnet) 7 is integrally fixed to the driver 4, and aluminum or the like is vapor-deposited on both the front and back surfaces of the deflectors 3u and 3d. Here, 3u is referred to as a first deflector, and 3d is referred to as a second deflector.

  The surface on which aluminum or the like is deposited is a deflection surface suitable for reflecting the beam. As shown in FIG. 1, the beams L1u and L2u are deflected by the first deflector 3u, and the beams L1d and L2d are deflected by the second deflector 3d.

  The first deflector 3u and the second deflector 3d are torsionally vibrated by the torsion springs 6u, 5u, 5d, and 6d around the swing axis O when the driver 4 receives a driving force from the actuator 9. Then, the beam is deflected and scanned.

  With reference to FIG. 2, the behavior of the first deflector 3u and the second deflector 3d in the present embodiment will be described. FIG. 2 shows changes with time in the behavior of the movable elements (deflectors) 3u and 3d, where the vertical axis represents the amplitude angle θ of the deflector and the horizontal axis represents time t.

The optical deflection unit 1 is driven at a frequency obtained by superimposing a plurality of natural frequencies (a fundamental frequency ω and a frequency 2ω that is twice the fundamental frequency) of the plate member 2. That is, the behavior of the two movers used for beam deflection is expressed by the following equation. In FIG. 2, φ = 0 and A ₃ = 0.

θ (t) = A ₁ sin (ωt) + A ₂ sin (2ωt + φ) + A ₃
A ₁ : Amplitude at the fundamental frequency (fundamental wave) A ₂ : Amplitude at a frequency (double wave) twice the fundamental frequency ω: Fundamental frequency φ: Phase difference between the fundamental wave and the harmonic A ₃ : Static angular error, For example, when the first deflector 3u, the second deflector 3d, and the driver 4 are in a stationary state, the amount of error from the design value is determined.

  According to the above equation, the behaviors of the first deflector 3u, the second deflector 3d, and the driver 4 are swung in the same phase at the fundamental frequency and in the opposite phase at twice the fundamental frequency. It can be obtained by superimposing the mode.

  Further, by appropriately setting each parameter, it is possible to approximate θ (t) ≈kt + α (K, α: constant) in a specific range within one cycle.

In this range, the first deflector 3u and the second deflector 3d have substantially equal angular velocities (dθ / dt = k).
1 oscillates, and the beams L1u, L1d, L2u, and L2d in FIG. 1 are deflected and scanned at a substantially constant angular velocity within a certain time range.

  Further, the plate member 2 has a symmetrical shape with respect to the swing axis O direction, and has a configuration in which the center of the driver element 4 is a symmetrical axis. Accordingly, the upper and lower first deflectors 3u and the second deflector 3d exhibit the same behavior around the swing axis O.

  As described above, the optical scanning device according to the present embodiment has two deflectors, and these are arranged apart from each other in the direction of the swing axis O with the driver 4 interposed therebetween, so the mirror surface size is increased. Even if not, the reflection point of each beam can be shifted in the swing axis O direction.

  As a result, it is possible to dispose the incident system with a wider pitch, but it is not necessary to increase the mirror size, that is, the size of the deflector more than necessary. Therefore, the torsion spring also has a minimum necessary length, and the entire optical scanning device can be prevented from becoming thicker than necessary in the swing axis O direction.

  Further, if the incident system is tilted in the sub-scanning direction, the pitch between the incident systems can be further increased, so that the size of the plate member 2 can be further reduced. At this time, the tilt angle of the incident system in the sub-scanning direction can be kept to the minimum necessary, and the influence on the imaging performance can be kept to the minimum.

  Further, since the plate member 2 is manufactured from one wafer, the same semiconductor process is executed between each of the plurality of movable elements 3u, 4, 3d and the plurality of torsion springs 6u, 5u, 5d, 6d. Therefore, there are few shape errors due to wafer variations and process variations.

  Further, the plate member 2 has a symmetrical shape in the direction of the swing axis O, and the first deflector 3u and the second deflector 3d behave in the same manner, so that the behavior of the scanned beam can be made uniform. Is possible. As a result, the print image quality in the image forming apparatus can be made uniform for each beam.

  In addition, since the first deflector 3u and the second deflector 3d are driven at a constant angular velocity during a part of the vibration period, when optical writing is performed using the part, a conventional rotary polygon mirror is used. It is possible to use substantially the same optical system as the optical scanning device that performs scanning deflection.

  In the case of sine wave drive, the scanning lens 44 needs to have a constant velocity using an f · arcsin θ lens or the like. However, if the velocity is completely uniform, the main scanning direction spot is enlarged at both ends of the image. Occurs. As a countermeasure, it is necessary to have a configuration in which the constant speed is compensated by an image clock. However, in the case of constant angular velocity driving as in this embodiment, it is not necessary to consider them.

  Furthermore, since the first deflector 3u and the second deflector 3d are separated from each other by the size of the actuator 9 or less, the possibility that the actuator 9 blocks the beam is low. Further, since the holder 8 has an opening at the site where the beam is scanned, light shielding by the holder 8 and vignetting of the beam can be avoided.

  Therefore, according to the present embodiment, it is possible to provide an optical scanning apparatus capable of accurately deflecting and scanning a plurality of beams while reducing the manufacturing cost with a compact configuration, and an image forming apparatus including the optical scanning apparatus. It becomes possible.

[Second Embodiment]
With reference to FIG. 7, an optical scanning device and an image forming apparatus including the same according to a second embodiment of the present invention will be described. FIG. 7 is a perspective view showing the overall configuration of the plate member according to the present embodiment. In addition, this Embodiment differs in the structure of the plate member 2 compared with the said 1st Embodiment. Since other configurations are not different from those of the first embodiment, description thereof is omitted here.

  As shown in FIG. 7, the plate member 2 in the present embodiment includes separate movers (dummy) 16 u and 16 d between the first deflector 3 u, the second deflector 3 d, and the driver 4. The point is to intervene. The movers 16u and 16d do not deflect the beam and do not receive a driving force from the actuator 9. The movable elements 16u and 16d are also connected in series to the torsion springs 17u, 5u, 5d, and 17u in the same manner as the first deflector 3u, the second deflector 3d, and the driver 4.

  In the first embodiment, the case where two deflectors and one drive element are provided has been described. However, even in a configuration in which at least one movable element is added, the same effect as described above is obtained. It is possible to obtain the effect.

  Thus, by adding at least one dummy mover, it becomes possible to oscillate the deflector by superimposing a plurality of different natural frequencies. High-value-added driving characteristics such as driving capable of correcting characteristics can be expected.

[Third Embodiment]
With reference to FIG. 8, an optical scanning device and an image forming apparatus including the same according to a third embodiment of the present invention will be described. FIG. 8 is a perspective view showing the overall configuration of the plate member according to the present embodiment. In addition, this Embodiment differs in the structure of the plate member 2 compared with the said 1st Embodiment. Since other configurations are not different from those of the first embodiment, description thereof is omitted here.

  As shown in FIG. 8, the plate member 2 according to the present embodiment is characterized in that the first deflector 3u, the second deflector 3d, and the driver 4 are supported as one side. Also, unlike the configuration of the plate member 2 in the first embodiment, the first deflector 3u is connected by one torsion spring 5u.

In the first embodiment, each deflector and driver are both supported by being connected to both ends of the plate member 2 by a torsion spring. However, even if, for example, one of the first deflector 3u and the second deflector 3d is a single-supported structure connected to the plate member 2 by a torsion spring, it has been described in the first embodiment. It is possible to obtain an effect similar to the effect.

[Fourth Embodiment]
With reference to FIG. 9, an optical scanning device and an image forming apparatus including the same according to a fourth embodiment of the present invention will be described. FIG. 9 is a perspective view showing the overall configuration of the plate member according to the present embodiment. In addition, this Embodiment differs in the structure of the plate member 2 compared with the said 1st Embodiment. Since other configurations are not different from those of the first embodiment, description thereof is omitted here.

  As shown in FIG. 9, the plate member 2 in the present embodiment is configured such that the second deflector 3 d and the driver 4 are integrally provided without a torsion spring, and are configured as one movable element. Is a feature. Even with this configuration, the first deflector 3u and the second deflector 3d can swing around the swing axis O.

According to this configuration, the number of torsion springs used can be two. Thus, even when the number of torsion springs is two, it is possible to obtain the same effect as the effect described in the first embodiment.

  As in the present embodiment, the number of movers provided on the plate member 2 may be two. If the amplitudes of these two movers are not uniform, the optical path lengths may be different from each other. However, among the photosensitive drums 32c, 32m, 32y, and 32k, the same optical path length can be maintained in 32c and 32k, and 32m and 32y. Therefore, it is not necessary to change the arrangement of the optical scanning system with respect to the plate member 2.

  Therefore, the scanning lenses 44 cm and 44 yk may be separated from each of the upper and lower first deflectors 3 u and the second deflector 3 d, and may have different shapes, and the optical path lengths may be aligned by a reflection mirror or the like.

[Fifth Embodiment]
With reference to FIGS. 10 and 11, an optical scanning device and an image forming apparatus including the same according to a fifth embodiment of the present invention will be described. FIG. 10 is a perspective view showing the overall configuration of the plate member according to the present embodiment. FIG. 11 is a perspective view showing the overall configuration of the optical scanning device according to the present embodiment. In the present embodiment, the configuration of the plate member 2 and the overall configuration of the optical scanning device are different from those of the first embodiment. Since other configurations are not different from those of the first embodiment, description thereof is omitted here.

  As shown in FIG. 10, the plate member 2 in the present embodiment has seven movers 3c, 3m, 3y, 3k, 4, 16u, and 16d, of which the movers 3c, 3m, 3y, and 3k are the first. It is characterized by being used as first to fourth deflectors. The movers 16u and 16d are dummy movers not provided with a deflection surface.

  In addition, a driver 4 is provided to resonately drive these deflectors, and is paired with an actuator 9 (not shown) to provide first to fourth deflectors 3c, 3m, 3y, 3k, dummy movers. 16u and 16d are driven to resonate.

  According to this configuration, the beam is deflected and scanned by the first to fourth deflectors 3c, 3m, 3y, and 3k as indicated by two-dot chain lines Lc, Lm, Ly, and Lk.

  Further, as shown in FIG. 11, the plate member 2 is provided in the light deflection unit 1. Further, in the optical scanning device according to the present embodiment, the beams emitted from the semiconductor lasers 41 c, 41 m, 41 y, and 41 k are incident on only one side surface of the plate member 2. Thereafter, after passing through one scanning lens 44, the light is guided to the corresponding photosensitive drums 32c, 32m, 32y, and 32k.

  Even with such a configuration, it is possible to obtain the same effects as those described in the first embodiment.

  Furthermore, according to the optical scanning device according to the present embodiment, since only one side of the plate member 2 is used, the difference between the front and back sides does not affect the deflection performance. For example, very high-precision flatness is required for the deflection surfaces of the deflectors 3c, 3m, 3y, and 3k. However, in the semiconductor process, the wafer is likely to be deformed such as warpage, and this deformation may cause image defects such as the spot shape being broken on the photosensitive drums 32c, 32m, 32y, and 32k.

If deflection scanning is performed using both the front and back surfaces of the plate member 2, the direction of warping is reversed between the front surface and the back surface, so that the difference may affect the deflection performance.

  However, since the plate member 2 in the present embodiment only performs deflection scanning using only one side, the directions of warpage are aligned. Therefore, it can be dealt with by correcting with the scanning lens 44.

  Thus, by aligning the warp directions of the first to fourth deflectors 3c, 3m, 3y, and 3k, it is possible to expect the effect that the imaging performance is aligned for each color and the print image quality is improved.

  Further, by adding at least one dummy mover as in the present embodiment, the deflector can be swung by overlapping a plurality of different natural frequencies. Therefore, it is possible to expect high added value driving characteristics such as driving with increased angular velocity and driving capable of correcting lens characteristics.

  Further, by arranging dummy movable elements 16u and 16d between the first to fourth deflectors 3c, 3m, 3y and 3k, the distance between the deflectors can be widened and the incident system pitch can be increased. become.

The perspective view which shows the whole structure of the plate member in 1st Embodiment. The figure which shows the behavior of the needle | mover in 1st Embodiment The perspective view which shows the whole structure of the light deflection | deviation unit in 1st Embodiment. The disassembled perspective view of the light deflection unit in the first embodiment The perspective view which shows the whole structure of the optical scanning device concerning 1st Embodiment. 1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. The perspective view which shows the whole structure of the plate member in 2nd Embodiment. The perspective view which shows the whole structure of the plate member in 3rd Embodiment. The perspective view which shows the whole structure of the plate member in 4th Embodiment. The perspective view which shows the whole structure of the plate member in 5th Embodiment. The perspective view which shows the whole structure of the optical scanner which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical deflection unit 3u 1st deflector 3d 2nd deflector 4 Driver 5u Torsion spring 5d Torsion spring 6u Torsion spring 6d Torsion spring 7 Permanent magnet 32 Photosensitive drum 41 Semiconductor laser L1u beam O Oscillation shaft

Claims (10)

A plurality of light sources for emitting beams;
An optical deflection unit for deflecting beams emitted from the plurality of light sources;
A plurality of imaging members for imaging the beam deflected in the light deflection unit on the surface of the photosensitive member corresponding to the beam;
In an optical scanning device comprising:
The light deflection unit is
A first deflector and a second deflector each having a beam deflecting surface formed on the surface;
A driver that receives driving force;
Driving means for driving the driver;
Have
The first deflector, the second deflector, and the driver are connected in series by a torsion spring;
An optical scanning device characterized in that the first deflector and the second deflector are configured to be swingable about a swing axis of the torsion spring by the drive means driving the driver. The driver is
The optical scanning device according to claim 1, wherein the optical scanning device is disposed between the first deflector and the second deflector. Between the first deflector and the second deflector,
The optical scanning apparatus according to claim 1, wherein at least one movable element that does not deflect a beam and does not receive a driving force from the driving unit is connected.   3. The optical scanning device according to claim 1, wherein either the first deflector or the second deflector and the driver are integrally provided without the torsion spring. 4. The deflection surface is
5. The optical scanning device according to claim 1, wherein the optical scanning device is formed on both front and back surfaces of the first deflector and the second deflector. 6. A plurality of light sources for emitting beams;
An optical deflection unit for deflecting beams emitted from the plurality of light sources;
A plurality of imaging members for imaging the beam deflected in the light deflection unit on the surface of the photosensitive member corresponding to the beam;
In an optical scanning device comprising:
The light deflection unit is
A first deflector, a second deflector, a third deflector, and a fourth deflector each having a beam deflecting surface formed thereon;
A driver that receives driving force;
Driving means for driving the driver;
Have
The first deflector, the second deflector, the third deflector, the fourth deflector, and the driver are connected in series by a torsion spring;
When the driving means drives the driver, the first deflector, the second deflector, the third deflector, and the fourth deflector swing around the swing axis of the torsion spring. An optical scanning device characterized by being configured. Between each deflector,
The optical scanning device according to claim 6, wherein a movable element that does not deflect a beam and that does not receive a driving force from the driving unit or the driving element is connected. The deflection surface is
The optical scanning device according to claim 6, wherein the optical scanning device is formed on both front and back surfaces of the first deflector, the second deflector, the third deflector, and the fourth deflector. The end of the torsion spring is
Held on the inner peripheral side of the plate member surrounding the torsion spring,
9. The optical scanning device according to claim 1, further comprising a holding member that integrally holds the plate member and the driving unit. An optical scanning device according to any one of claims 1 to 9,
A plurality of photoreceptors on which a beam deflected from the optical scanning device is imaged;
Transfer means for transferring an image formed on the photoreceptor onto a sheet material;
An image forming apparatus comprising:

Images