JP2011095587A - Optical scanner and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner capable of preventing an image from deteriorating by making a joint of scanning lines inconspicuous even if the deflection angle of the MEMS mirror changes during the scan. <P>SOLUTION: The optical scanner 13 forms one linear electrostatic latent image on a photosensitive drum 2a, by deflecting light beams L1 and L2 emitted by light sources 27a and 27b by the MEMS mirror (deflecting element 26), and joining, in a main-scanning direction, a plurality of scanning lines R1 and R2 formed on the photosensitive drum (image carrier) 2a forming an image with the deflected light beams L1 and L2 through scanning lenses 31 and 32. In the optical scanner, a scan, on the photosensitive drum 2a in the main-scanning direction with the plurality of light beams L1 and L2 deflected by the MEMS mirror, is started from a joint of the plurality of scanning lines R1 and R2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical scanning device using a MEMS mirror as a deflecting unit and an image forming apparatus such as a copying machine and a printer provided with the optical scanning device.

  In an image forming apparatus such as a copying machine or a printer, an image carrier whose surface is uniformly charged by a charger is exposed and scanned by an optical scanning device, and an electrostatic latent image corresponding to image information is formed on the surface. The The electrostatic latent image is developed by a developing device using toner as a developer to be visualized as a toner image. The toner image is transferred onto a sheet by a transfer device and then heated and heated by a fixing device. A series of image forming operations is completed by discharging the sheet having the toner image fixed thereon by being pressed and fixed on the sheet.

  Conventionally, a polygon mirror or a galvanometer mirror is exclusively used as a deflector for scanning a light beam in an optical scanning device. In order to achieve higher resolution images and high-speed printing, these polygon mirrors are used. And galvanometer mirrors need to be rotated at higher speeds.

  However, if the polygon mirror or galvanometer mirror is rotated at a high speed, problems such as heat generation and noise due to bearing durability, windage loss, and the like are limited.

  Accordingly, in recent years, a deflector using silicon micromachining (MEMS) technology has been developed. For example, a micromirror (hereinafter referred to as a “MEMS mirror”) and a torsion beam supporting the micromirror are integrated into a Si substrate. An AC voltage is applied between the movable electrode on the MEMS mirror side and the fixed electrode on the fixed side, and the MEMS mirror is reciprocated using resonance while twisting the torsion beam by electrostatic attraction generated between both electrodes. A method of vibrating is proposed (see, for example, Patent Document 1).

  According to the above method, the MEMS mirror can reciprocally vibrate (sinusoidal vibration) using resonance, so that it can be operated at high speed, and noise and power consumption can be kept low. The deflection angle (deflection angle) is smaller than that of the polygon mirror, and the size of the reflecting surface is limited.

  Therefore, for example, in Patent Document 2, a plurality of optical scanning units including a vibrating mirror (MEMS mirror) and a scanning lens are arranged side by side to divide an image region into a plurality corresponding to the number of optical scanning units, and adjacent light. A configuration has been proposed in which scanning lines by a scanning unit are connected in the main scanning direction.

However, MEMS mirrors using the resonance phenomenon of the Si base material vary in the inherent resonance frequency, and therefore have different deflection angles (vibration angles) and are scanned in the main scanning direction on the image carrier. There arises a problem that misalignment or overlap occurs at the joint of the lines, and that portion becomes conspicuous and causes image degradation.
This is called a child, and the resonance characteristics change due to temperature changes, so that the deflection angle (shake angle) fluctuates, the scanning range expands and contracts, and the scanning lines connected in the main scanning direction on the image carrier are connected. There arises a problem that misalignment or overlap occurs in the eyes, and that portion becomes conspicuous and causes image degradation.

  Therefore, for example, in Patent Document 3, the scanning direction in each of the plurality of optical scanning modules arranged so that the scanning lines are aligned in the main scanning direction is described in order to prevent the positional deviation in the sub-scanning direction of the joints of the scanning lines. There is a proposal to match the timing of starting the recording with the optical scanning module arranged on the scanning start side by ending the recording by shifting the recording start field timing with respect to the adjacent optical scanning module at the start of scanning. Yes.

  Further, in Patent Document 4, a light beam is detected by a synchronization detection sensor (BD sensor) and a terminal detection sensor, and a twist angle of a vibrating mirror (MEMS mirror) is detected based on a time difference between the detection signals. A configuration has been proposed in which the gain of a voltage pulse to be applied is adjusted until a predetermined reference value is reached, so that the joints of the scanning lines are less noticeable even if there is a variation in the resonance frequency unique to the vibrational moller.

  Furthermore, Patent Document 5 discloses an optical scanning device that prevents the deterioration of scanning performance due to splicing scanning by changing the division position of image information between forward scanning and backward scanning of each movable mirror (MEMS mirror). Proposed.

Japanese Patent No. 2924200 Japanese Patent Laid-Open No. 2004-184843 JP 2002-267966 A JP 2004-279947 A JP 2006-201678 A

  However, since the Young's modulus of the Si substrate constituting the MEMS mirror changes with temperature, the resonance characteristics also change, and the deflection angle (runout angle) of the MEMS mirror fluctuates due to the temperature change during scanning, so that the scanning range expands and contracts. When the deflection angle decreases, white spots occur at the joints of the scanning lines, and when the deflection angle increases, the images overlap and become thick.

  The present invention has been made in view of the above problems, and the object of the present invention is to make the joint of the scanning lines inconspicuous regardless of the change in the deflection angle of the MEMS mirror during scanning. An object of the present invention is to provide an optical scanning device capable of preventing the occurrence of deterioration and an image forming apparatus provided with the same.

  In order to achieve the above object, the invention according to claim 1 is formed on the image carrier by deflecting the light beam emitted from the light source by the MEMS mirror and forming an image of the deflected light beam by the scanning lens. In the optical scanning device for forming a single line-shaped electrostatic latent image on the image carrier by connecting a plurality of scanning lines in the main scanning direction, the image by the plurality of light beams deflected by the MEMS mirror. The scanning in the main scanning direction on the carrier is started from the joint of a plurality of scanning lines.

  According to a second aspect of the present invention, in the first aspect of the invention, two BD sensors are arranged outside the effective scanning range of the light beam, and at the timing when one BD sensor detects one light beam, the other is detected. The scanning with the image carrier by the light beam is started.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the adjusting mechanism may be at least one of a folding mirror that folds back a light beam from the BD sensor, the scanning lens, or the light source and guides it to the BD sensor. Is provided.

  An image forming apparatus according to a fourth aspect includes the optical scanning device according to any one of the first to third aspects.

  According to the present invention, the scanning in the main scanning direction on the image carrier by the plurality of light beams deflected by the MEMS mirror is started from the joint of the plurality of scanning lines. Even if the deflection angle of the MEMS mirror fluctuates, the joints of the scanning lines can be made inconspicuous regardless of this, and image degradation due to white spots or overlapping of images at the joints can always be ensured. Can be prevented.

1 is a side sectional view of an image forming apparatus (color laser printer) according to the present invention. It is a main scanning sectional view of the optical scanning device concerning the present invention. It is a sub-scanning sectional view of the optical scanning device concerning the present invention. It is a front view of the deflection | deviation element of the optical scanning device concerning this invention. It is the sectional view on the AA line of FIG. It is a main scanning sectional view of an optical scanning device concerning another form of the present invention. It is a sub-scanning sectional view of an optical scanning device concerning another form of the present invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Image forming apparatus]
FIG. 1 is a cross-sectional view of a color laser printer as an embodiment of an image forming apparatus according to the present invention. The illustrated color laser printer is a tandem type, and a magenta image forming unit is provided at the center of the main body 100. 1M, a cyan image forming unit 1C, a yellow image forming unit 1Y, and a black image forming unit 1K are arranged in tandem at regular intervals.

  Each of the image forming units 1M, 1C, 1Y, and 1K is provided with photosensitive drums 2a, 2b, 2c, and 2d, which are image carriers, and a charger 3a is disposed around each of the photosensitive drums 2a to 2d. 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d and drum cleaning devices 6a, 6b, 6c, 6d, respectively.

  Here, the photosensitive drums 2a to 2d are drum-shaped photosensitive members, and are driven to rotate at a predetermined process speed in a direction indicated by an arrow (clockwise) by a driving motor (not shown). The chargers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing devices 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (K) toner, respectively, and are formed on the photosensitive drums 2a to 2d. In addition, the toner of each color is attached to each electrostatic latent image to visualize each electrostatic latent image as a toner image of each color.

  The transfer rollers 5a to 5d are arranged so as to be able to contact the photosensitive drums 2a to 2d via the intermediate transfer belt 7 in the respective primary transfer portions. Here, the intermediate transfer belt 7 is stretched between the driving roller 8 and the tension roller 9 and is disposed on the upper surface side of each of the photosensitive drums 2a to 2d. The driving roller 8 is a secondary roller. The transfer unit is disposed so as to be in contact with the secondary transfer roller 10 via the intermediate transfer belt 7. A belt cleaning device 11 is provided in the vicinity of the tension roller 9.

  Incidentally, toner containers 12a, 12b, 12c, and 12d for supplying toner to the developing devices 4a to 4d are arranged in a line above the image forming units 1M, 1C, 1Y, and 1K in the printer main body 100. It is installed.

  Further, below the image forming units 1M, 1C, 1Y, and 1K in the printer main body 100, a total of four optical scanning devices 13 according to the present invention are provided corresponding to the image forming units 1M, 1C, 1Y, and 1K. The paper feed cassette 14 is detachably installed at the bottom of the printer main body 100 below each of these. A plurality of sheets of paper (not shown) are stacked and stored in the paper feed cassette 14. A pickup roller 15 for picking up paper from the paper feed cassette 14 and a picked up paper are located near the paper feed cassette 14. A feed roller 16 and a retard roller 17 are provided for separating the toner and feeding them one by one to the transport path S.

  Further, the conveyance path S extending in the vertical direction on the side of the printer main body 100 includes a conveyance roller pair 18 that conveys the sheet, and the secondary transfer counter roller 8 and the second transfer opposing roller 8 at a predetermined timing after the sheet is temporarily held. A registration roller pair 19 is provided to be supplied to a secondary transfer portion which is a contact portion with the next transfer roller 10. Next to the transport path S, another transport path S ′ that is used when images are formed on both sides of the paper is formed. A plurality of reversing roller pairs 20 are appropriately used for the transport path S ′. Are provided at regular intervals.

  By the way, the conveyance path S arranged in the vertical direction on one side of the printer main body 100 extends to the paper discharge tray 21 provided on the upper surface of the printer main body 100, and the fixing device 22 and the discharge path are disposed in the middle. Paper roller pairs 23 and 24 are provided.

  Next, an image forming operation by the color laser printer having the above configuration will be described.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate at a predetermined process speed in the direction of the arrow (clockwise) in the image forming units 1M, 1C, 1Y, and 1K, and these photosensitive drums 2a. ˜2d are uniformly charged by the chargers 3a to 3d. Each optical scanning device 13 emits a light beam modulated by a color image signal for each color, irradiates the surface of each photosensitive drum 2a to 2d with each light beam, and each color on each photosensitive drum 2a to 2d. The electrostatic latent images corresponding to the color image signals are respectively formed.

  First, magenta toner is attached to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charged polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. This magenta toner image is moved in the direction of the arrow in the figure by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied in the primary transfer portion (transfer nip portion) between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 7 that is rotationally driven.

  The intermediate transfer belt 7 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred to the magenta toner image on the intermediate transfer belt 7 in the primary transfer portion in the same manner as described above.

  Similarly, yellow and black toners respectively formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1K on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 7, respectively. The images are sequentially superimposed at each primary transfer portion, and a full-color toner image is formed on the intermediate transfer belt 7. The transfer residual toner which is not transferred onto the intermediate transfer belt 7 and remains on the photosensitive drums 2a to 2d is removed by the drum cleaning devices 6a to 6d, and the photosensitive drums 2a to 2d are prepared for the next image formation. It is done.

  Then, in accordance with the timing at which the front end of the full-color toner image on the intermediate transfer belt 7 reaches the secondary transfer portion (transfer nip portion) between the drive roller 8 and the secondary transfer roller 10, The sheet fed to the transport path S by the feed roller 16 and the retard roller 17 is transported to the secondary transfer unit by the registration roller pair 19. Then, a full-color toner image is collectively transferred from the intermediate transfer belt 7 to the sheet conveyed to the secondary transfer unit by the secondary transfer roller 10 to which a secondary transfer bias having a polarity opposite to that of the toner is applied. .

  Thus, the sheet on which the full-color toner image has been transferred is conveyed to the fixing device 22, and the sheet on which the full-color toner image has been fixed by being heated and pressurized and thermally fixed on the surface of the sheet. Then, the paper is discharged onto the paper discharge tray 21 by the paper discharge roller pair 23 and 24, and a series of image forming operations is completed. The transfer residual toner that is not transferred onto the sheet and remains on the intermediate transfer belt 7 is removed by the belt cleaning device 11, and the intermediate transfer belt 7 is prepared for the next image formation.

[Optical scanning device]
Next, the optical scanning device 13 according to the present invention will be described with reference to FIGS. Since all the four optical scanning devices 13 have the same configuration, only one optical scanning device 13 will be described below.

  2 is a main scanning sectional view of the optical scanning device according to the present invention, FIG. 3 is a sub-scanning sectional view of the main part of the optical scanning device, FIG. 4 is a front view of a deflection element of the optical scanning device, and FIG. It is an AA sectional view taken on the line.

  As shown in FIG. 2, one deflection element 26 is disposed at one end on the center line CL in the casing 25 of the optical scanning device 13, and both sides of the deflection element 26 are sandwiched between the deflection elements 26 of the casing 25. A pair of laser light sources (laser diodes) 27a and 27b are attached below (upper and lower in FIG. 2). A pair of collimator lenses 28a and 28b, cylindrical lenses 29a and 29b, and folding mirrors 30a and 30b form a center line CL in the emission direction of the light beams L1 and L2 from the laser light sources 27a and 27b in the housing 25. As a border, they are arranged symmetrically on both sides.

  On the center line CL in the housing 25, scanning lenses 31 and 32 are arranged along the traveling direction of the light beams L1 and L2 reflected by the deflection element 26, respectively. In addition, the center line CL in the housing 25 is located at a symmetric position on both sides thereof, and the position is outside the effective scanning range (scanning range actually used as the print width) R of the light beams L1 and L2. A pair of BD sensors 33a and 33b are respectively arranged.

  Here, the configuration and operation of the deflection element 26 will be described with reference to FIGS.

  In the deflection element 26, an ellipsoidal MEMS mirror 36 and a torsion beam 37 supporting the same are integrated into a Si substrate 35 bonded on a frame 34 by using a micromachining technique (MEMS technique) such as etching or film formation. The MEMS mirror 36 reciprocates around the torsion beam 37 as a center.

  As shown in FIG. 4, both ends in the longitudinal direction (X-axis direction) of the torsion beam 37 are electrically insulated by an insulating portion 38, and both sides in the width direction are orthogonal to the longitudinal direction (Y-axis direction). A plurality of comb-like movable electrodes 39 extending in a straight line are formed, and a plurality of fixed electrodes 40 positioned between the movable electrodes 39 are formed on the main body 35 A side of the Si substrate 35. The fixed electrodes 40 are alternately arranged along the longitudinal direction (X-axis direction) of the torsion beam 37. As shown in FIG. 5, electric wires 41 and 42 extending from an AC power source (not shown) are connected to the movable electrode 39 and the fixed electrode 40, respectively.

  In the deflection element 26 configured as described above, when an AC voltage is applied from the AC power source to the movable electrode 39 and the fixed electrode 40 via the electric wires 41 and 42, the distance between the movable electrode 39 and the fixed electrode 40 is set. Electrostatic attractive force is generated at this time, and the MEMS mirror 36 reciprocates by a predetermined angle (deflection angle) about the torsion beam 37 (X axis) as shown by a chain line in FIG. The drive frequency of the MEMS mirror 36 is set to the resonance frequency, and thereby the amplitude (deflection angle) of the MEMS mirror 36 is expanded. Also, an aluminum film or the like is formed on the surface (reflection surface) of the MEMS mirror 36 to increase the reflectance.

  Thus, when the pair of laser light sources 27a and 27b are ON / OFF controlled according to the image data, the light beams L1 and L2 modulated in accordance with the image data are emitted from the laser light sources 27a and 27b, respectively. The light beams L1 and L2 are shaped into collimated light of an appropriate size by the collimator lenses 28a and 28b, respectively, and then incident on the cylindrical lenses 29a and 29b having power only in the sub-scanning direction (Y-axis direction), respectively. Is done. Then, the light beams L1 and L2 that have passed through the cylindrical lenses 29a and 29b are folded back by the folding mirrors 30a and 30b, and then are applied to the MEMS mirror 36 (see FIG. 4) of one (common) deflection element 26. Incident and imaged.

  The light beams L1 and L2 incident on the MEMS mirror 36 of the deflection element 26 are scanned in the main scanning direction (X-axis direction) by the MEMS mirror 36 reciprocatingly vibrating as described above, and pass through the scanning lenses 31 and 32. As a result, an image is formed on the photosensitive drum 2a (2b, 2c, 2d) of each image forming unit 1M (1C, 1Y, 1K), and the photosensitive drum 2a (2b, 2c, 2d) is formed on the scanning lines R1, R2. Along the exposure scan. As a result, the scanning lines R1, R2 on the photosensitive drum 2a (2b, 2c, 2d) by the light beams L1, L2 are centered in the main scanning direction (axial direction) of the photosensitive drum 2a (2b, 2c, 2d) (housing 25). In this embodiment, scanning in the main scanning direction by the light beams L1 and L2 is started from the joint of the scanning lines R1 and R2, and the connection is performed. Scanning from the eyes toward both ends of the photosensitive drum 2a (2b, 2c, 2d) is performed in the direction indicated by the arrow in the drawing.

  Here, the BD sensors 33a and 33b arranged outside the effective scanning range R detect the light beams L1 and L2, respectively, so that the light beams L1 and L2 are applied onto the photosensitive drum 2a (2b, 2c and 2d). Although the exposure scanning (writing) start timing is determined, in the present embodiment, one BD sensor 33a has the light beam L2 at the joint of the scanning lines R1 and R2 (on the center line CL in the housing 25). It is arranged at a position to detect the other light beam L1 when deflected. Similarly, the other BD sensor 32b is disposed at a position to detect the other light beam L2 when the light beam L1 is deflected at the joint between the scanning lines R1 and R2.

  Accordingly, scanning of the photosensitive drum 2a (2b, 2c, 2d) by the other light beam L2 is started at the timing when one BD sensor 33a detects the light beam L1, and the other BD sensor 33b detects the light beam L2. At this timing, scanning with the other light beam L1 on the photosensitive drum 2a (2b, 2c, 2d) is started.

  As described above, in the present embodiment, scanning in the main scanning direction on the photosensitive drum 2a (2b, 2c, 2d) by the light beams L1, L2 deflected by the MEMS mirror 36 is performed on the two scanning lines R1, R2. Scanning (irrespective of the change in the deflection angle of the MEMS mirror 36 due to a temperature change during scanning, etc.), since it starts from the joint (axial center of the photosensitive drum 2a (2b, 2c, 2d)). The lines R1 and R2 are not displaced or overlapped at all, and the joints can be made inconspicuous, and it is always possible to reliably prevent the occurrence of image deterioration due to white spots or overlapping of images at the joints. it can.

  Here, in the present embodiment, the BD sensors 33a and 33b are provided with adjustment mechanisms, and the positions of the BD sensors 33a and 33b are adjusted by the adjustment mechanisms in the direction of the arrows as indicated by broken lines in FIG. Depending on this adjustment, the scanning in the main scanning direction on the photosensitive drum 2a (2b, 2c, 2d) by the light beams L1, L2 deflected by the MEMS mirror 36 as described above can be performed. , R2 (starting from the axial center of the photosensitive drums 2a (2b, 2c, 2d)). Similarly, by providing an adjustment mechanism in the scanning lenses 31 and 32 and the folding mirrors 30a and 30b, the scanning in the main scanning direction can be adjusted to start from the joint between the two scanning lines R1 and R2.

  In the present embodiment, the light beams L1 and L2 emitted from the two laser light sources 27a and 27b are deflected by the MEMS mirror 36 of one (common) deflecting element 26, and these light beams L1 and L2 are deflected. In this way, the photosensitive drum 2a (2b, 2c, 2d) is exposed and scanned to connect the scanning lines R1, R2 on the photosensitive drum 2a (2b, 2c, 2d) in the main scanning direction. The present invention can also be applied to the optical scanning device shown in FIG.

  That is, FIG. 6 is a main scanning sectional view of an optical scanning device according to another embodiment of the present invention, and FIG. 7 is a sub-scanning sectional view of the optical scanning device, which are shown in FIGS. The same elements are denoted by the same reference numerals, and description thereof will be omitted below.

  As shown in FIG. 6, one deflection element 26, a laser light source (laser diode) 27, an optical switch 43, and scanning lenses 31 and 32 are arranged on the center line CL in the housing 25 of the optical scanning device 13. A pair of folding mirrors 44a and 44b are arranged so as to be symmetrical on both sides (left and right in FIG. 6) of the center line CL. The optical switch 43 switches light emitted from the laser light source 27 to two optical paths, and uses an electro-optic effect, a thermo-optic effect, a liquid crystal element or a nonlinear optical element. The one used is used.

  A pair of BD sensors 33a and 33b are arranged at positions outside the effective scanning range R in the housing 25, respectively.

  Thus, when one (common) laser light source 27 is ON / OFF controlled according to image data, a light beam L modulated according to the image data is emitted from the laser light source 27. The optical path of the light beam L is switched to two by the optical switch 43, and the two light beams L 1 and L 2 are alternately emitted from the optical switch 43. The light beams L1 and L2 are folded by the folding mirrors 44a and 44b, and then incident on the MEMS mirror 36 (see FIG. 4) of one (common) deflection element 26 to form an image.

  The light beams L1 and L2 incident on the MEMS mirror 36 of the deflection element 26 are scanned in the main scanning direction (X-axis direction) when the MEMS mirror 36 shown in FIG. As a result, an image is formed on the photosensitive drums 2a (2b, 2c, 2d) of the image forming units 1M (1C, 1Y, 1K) shown in FIG. 1, and scanning lines are formed on the photosensitive drums 2a (2b, 2c, 2d). Exposure scanning is performed along R1 and R2. As a result, the scanning lines R1, R2 on the photosensitive drum 2a (2b, 2c, 2d) by the light beams L1, L2 are centered in the main scanning direction (axial direction) of the photosensitive drum 2a (2b, 2c, 2d) (housing 25). In this case, scanning in the main scanning direction by the light beams L1 and L2 is started from the joint of the scanning lines R1 and R2.

  Therefore, in the optical scanning device 13 shown in FIGS. 6 and 7, even if the deflection angle of the MEMS mirror 36 fluctuates due to a temperature change during scanning, the scanning lines R1 and R2 are not displaced or overlapped at all. The same effect as described above can be obtained, in which the joint can be made inconspicuous, and the occurrence of image degradation caused by white spots or overlap of images at the joint can be always reliably prevented. .

  Although the present invention has been described with respect to a mode in which the present invention is applied to a color laser printer and an optical scanning device provided in the color laser printer, the present invention is not limited to any other image forming apparatus including a monochrome printer or a copying machine. Of course, the present invention can be similarly applied to the optical scanning device provided for this.

1M Magenta image forming unit 1C Cyan image forming unit 1Y Yellow image forming unit 1K Black image forming unit 2a to 2d Photosensitive drum (image carrier)
3a to 3d charger 4a to 4d developing device 5a to 5d transfer roller 6a to 6d drum cleaning device 7 intermediate transfer belt 8 drive roller 9 tension roller 10 secondary transfer roller 11 belt cleaning device 12a to 12d toner container 13 optical scanning device 14 Paper cassette 15 Pickup roller 16 Feed roller 17 Retard roller 18 Transport roller pair 19 Registration roller pair 20 Transport roller pair 21 Paper discharge tray 22 Fixing device 23, 24 Paper discharge roller pair 25 Case 26 Deflection element 27 Laser light source (light source)
27a, 27b Laser light source (light source)
28a, 28b Collimator lens 29a, 29b Cylindrical lens 30a, 30b Folding mirror 31, 32 Scan lens 33a, 33b BD sensor 34 Deflection element frame 35 Si substrate 35A Si substrate body 36 Deflection element MEMS mirror 37 Deflection element torsion beam 38 Deflection element insulation part 39 Deflection element movable electrode 40 Deflection element fixed electrode 41, 42 Deflection element wire 43 Optical switch 44a, 44b Folding mirror CL Case center line L1, L2 Light beam R Effective scanning range R1, R2 Scan line S, S 'Transport path

Claims (4)

A light beam emitted from the light source is deflected by a MEMS mirror, and the deflected light beam is imaged by a scanning lens to connect a plurality of scanning lines formed on the image carrier in the main scanning direction. In an optical scanning device for forming a line-shaped electrostatic latent image on an image carrier,
An optical scanning device characterized in that scanning in the main scanning direction on the image carrier by a plurality of light beams deflected by the MEMS mirror is started from a joint of a plurality of scanning lines.   Two BD sensors are arranged outside the effective scanning range of the light beam, and scanning on the image carrier by the other light beam is started at the timing when one BD sensor detects the one light beam. The optical scanning device according to claim 1.   3. The optical scanning device according to claim 1, wherein an adjustment mechanism is provided in at least one of a folding mirror that folds a light beam from the BD sensor, the scanning lens, or the light source and guides the light beam to the BD sensor. . An image forming apparatus comprising the optical scanning device according to claim 1.

Images