JP4683016B2 - Optical scanning apparatus and printing apparatus - Google Patents

Description

  The present invention relates to an optical scanning device including a vibrating mirror.

  For example, some optical scanning devices provided in laser printers use a vibrating mirror (micromirror) in addition to those using a polygon mirror that is rotationally driven by a motor. In this method, the oscillating mirror is driven to vibrate with an electrostatic force, the laser beam from the light source is deflected by the oscillating mirror, and reciprocally scanned on the photosensitive member. FIG. 11 is a diagram showing the relationship between the rotation angle of the oscillating mirror and the scanning locus of the laser beam on the photosensitive member in the conventional optical scanning device. A central portion (solid line portion in the drawing) excluding both end portions (broken line portion in the drawing) in such laser beam scanning is a printing region where an image is actually formed. As can be seen from the drawing, the distance (d1, d2) between the main scanning line R ends adjacent to each other in the sub-scanning direction is different in the configuration in which the laser beam is reciprocally scanned on the photosensitive member using the vibrating mirror. For this reason, scanning distortion may occur.

Therefore, Patent Document 1 has a configuration in which two laser beams are reciprocally scanned at different positions on the photosensitive member by a vibrating mirror, a scanning line in the forward direction (or sub-scanning direction) by one laser beam, and the other laser. One scanning line is formed on the photosensitive member by combining the scanning line in the forward direction with light.
JP 2005-338512 A

However, in the configuration of Patent Document 1, one scanning line on the photosensitive member is formed by using two scanning lines of laser light directed in the same direction, so that the main scanning lines at both ends of the main scanning line are eventually formed. The distance difference between the ends does not change. For this reason, for example, although the photosensitive member is desired to be exposed at the same density (the same image forming density), the exposure quality is deteriorated, such as a difference in density between a portion where the distance difference is small and a portion where the distance difference is large. There was a problem.
The present invention has been completed based on the above circumstances, and an object of the present invention is to provide an optical scanning device and a printing device capable of suppressing a reduction in exposure quality.

As means for achieving the above object, an optical scanning device according to a first aspect of the present invention is a first emission means for emitting a first light beam, a second emission means for emitting a second light beam, and the first An oscillating mirror that reciprocally scans one light beam and the second light beam at different positions on the surface to be scanned, and the first emitting means and the second emitting means within a printing region on the scanned surface. The vibration mirror is turned on from off in the middle of the forward path, and is turned on from off in the middle of the return path by the vibration mirror, or is turned on from off in the printing area in the middle of the forward path by the vibration mirror. return the way in from off to on, the part or all of one scanning line by the scanning by the second light beam and scanning by the first light beam scanning direction are different from each other And a control means for forming on the scanning surface.
According to the present invention, in the printing area on the scanned surface, the vibration mirror is turned on to off in the middle of the forward path, and the vibration mirror is turned on to off in the middle of the return path. A part of or all of a scanning line is scanned by scanning with the first light beam and scanning with the second light beam , which are switched from off to on in the middle and turned from off to on in the middle of the return path by the vibrating mirror. It is the structure formed on a surface. Thereby, compared with the conventional structure which forms one scanning line by the scanning of the light beam of the same scanning direction, the space | interval error of scanning lines can be suppressed, and the fall of exposure quality can be suppressed.

The second invention is the optical scanning device according to the first invention, wherein the control means is arranged in the forward direction by the first light beam on one side with respect to the center position in the sub-scanning direction on the surface to be scanned. Scanning and scanning in the forward direction by the second light beam are alternately performed for each scanning line, and on the other side, scanning in the backward direction by the first light beam and scanning in the backward direction by the second light beam are performed. Is alternately executed for each scanning line.
According to the present invention, the control means only needs to repeatedly execute a predetermined on / off pattern for the first emission means and the second emission means, and the control content can be made relatively simple.

A third invention is the optical scanning device according to the first or second invention, wherein a joint portion between the scanning by the one light beam and the scanning by the other light beam is adjacent to each other in the one scanning line. The scanning lines are different from each other in the main scanning direction.
According to the present invention, at one scanning line, the joint portion between the scanning with one light beam and the scanning with the other light beam is different between at least adjacent scanning lines. Therefore, the influence of the joint portion in the entire image can be suppressed as compared with the case where the joint portion is the same between adjacent scanning lines.

A fourth invention is the optical scanning device according to any one of the first to third inventions, and is provided in an optical path between the vibrating mirror and the scanned surface, and the first light beam and the An optical system is provided that displaces the central portion of the image of the second light beam in the main scanning direction in a direction opposite to the moving direction of the surface to be scanned from both ends.
When a scanning line is formed by light beams having different scanning directions, the scanning line has an arc shape (so-called bow) in which a joint portion protrudes in the moving direction of the surface to be scanned. On the other hand, according to the present invention, the central portion in the main scanning direction of the image by the first light beam and the second light beam is made larger by the optical system in the direction opposite to the moving direction of the surface to be scanned than at both ends. Displace. Therefore, the influence of the arc shape can be suppressed.

A fifth invention is the optical scanning device according to any one of the first to fourth inventions, wherein setting means for setting an image quality priority mode and a speed priority mode is provided, and the control means has the image quality priority When the mode is set, the first control is executed to form part or all of one scanning line on the surface to be scanned by scanning with the first light beam and the second light beam having different scanning directions. When the speed priority mode is set, the second control is executed to simultaneously form separate scanning lines by scanning the first light beam and the second light beam.
According to the present invention, if the image quality priority mode is set when exposure is desired with high quality, exposure with suppressed scanning distortion can be performed by executing the first control, and speed priority is given when high speed exposure is desired. If the mode is set, high-speed exposure for simultaneously forming a plurality of scanning lines can be performed by the second control.
A printing apparatus according to a sixth aspect of the present invention includes a photoconductor and the optical scanning device according to any one of claims 1 to 5 that exposes the photoconductor, and the exposed photoconductor A printing unit is provided that forms an image and transfers the image to a printing medium.

  According to the present invention, an interval error between scanning lines can be suppressed as compared with a conventional configuration in which one scanning line is formed by scanning light beams in the same scanning direction, and a reduction in exposure quality can be suppressed. .

<Embodiment 1>
Embodiment 1 of the present invention will be described with reference to FIGS.
(Whole structure of laser printer)
FIG. 1 is a side sectional view of a main part of a laser printer (an example of a printing apparatus) 1. The laser printer 1 includes a feeder unit 4 for feeding paper 3 (an example of a printing medium) in a main body frame 2 and a printing unit for forming an image on the paper 3 fed by the feeder unit 4. 5 etc.

1. Feeder Unit The feeder unit 4 includes a paper feed tray 6, a pressing plate 7, a paper feed roller 8 and a separation pad 9, paper dust removing rollers 10 and 11, and a registration roller 12. The separation pad 9 is pressed against the paper feed roller 8 by a spring 13. In the following description, the right side in FIG. 1 is the front side of the laser printer 1 and the left side in FIG. 1 is the rear side of the laser printer 1.

  The pressing plate 7 is rotatable around its rear end portion, and its front end portion is urged upward by a spring (not shown). As a result, the uppermost sheet 3 on the pressing plate 7 is pressed toward the sheet feeding roller 8. The sheet 3 on the pressing plate 7 is nipped between the sheet feeding roller 8 and the separation pad 9 by the rotation of the sheet feeding roller 8 and then fed one by one.

  The fed paper 3 is sent to the registration roller 12 after the paper dust is removed by the paper dust removing rollers 10 and 11. The registration roller 12 sends the paper 3 to the transfer position after registration. This transfer position is a position at which the toner image on the photosensitive drum 27 is transferred to the paper 3, and is a contact position between the photosensitive drum 27 (an example of a photosensitive member) and a transfer roller 30 (an example of a transfer unit). The

2. Printing Unit The printing unit 5 includes a scanner unit 16, a process cartridge 17, and a fixing unit 18.

  FIG. 2 is a schematic diagram illustrating the configuration of the scanner unit 16 (an example of an optical scanning device). The light source unit 20 performs an on / off operation based on the image signal. Laser light (an example of a light beam) L emitted from the light source unit 20 is deflected by the vibrating mirror 19 as indicated by a chain line in FIG. The laser beam L deflected here forms an image on the surface of the photosensitive drum 27 by passing through the optical system 21, and forms an electrostatic latent image in the print region E on the surface of the photosensitive drum 27. The optical system 21 is, for example, an arc sine lens that focuses the laser beam L deflected by the vibrating mirror 19 on the surface of the photosensitive drum 27 and scans the surface of the photosensitive drum 27 at a constant speed. The scanner unit 16 is provided with a BD sensor 22 (an example of an optical sensor) that detects the laser light L that has passed through the optical system 21 at a predetermined position. Specifically, the laser light L that has passed through the optical system 21 is configured to be incident on the BD sensor 22 via the reflection mirror 23.

  The detection timing of the laser beam L by the BD sensor 22 is used to measure the start timing of irradiating the laser beam L in the printing area E. In addition, it is also used for controlling the period and swing width of the vibrating mirror. Details of the light source unit 20 and the vibrating mirror 19 will be described later.

  The process cartridge 17 includes a developing roller 31, a layer thickness regulating blade 32, a supply roller 33, and a toner hopper 34. The toner in the toner hopper 34 is stirred by the agitator 36 and discharged from the toner supply port 37. A developing bias voltage is applied to the developing roller 31 by an application circuit (not shown) during development.

  The toner discharged from the toner supply port 37 is supplied to the developing roller 31 by the rotation of the supplying roller 33 and is positively frictionally charged between the supplying roller 33 and the developing roller 31. Further, the toner supplied onto the developing roller 31 is carried on the developing roller 31 as a thin layer by the layer thickness regulating blade 32.

  The process cartridge 17 further includes a photosensitive drum 27, a scorotron charger 29, a transfer roller 30, and a cleaning brush 53. The surface of the photosensitive drum 27 (an example of a surface to be scanned) is positively charged by the charger 29 and then exposed by the laser light L from the scanner unit 16 to form an electrostatic latent image.

  Next, the toner carried on the surface of the developing roller 31 is supplied to the electrostatic latent image formed on the photosensitive drum 27 and developed. A transfer bias voltage is applied to the transfer roller 30 by an application circuit (not shown) during a transfer operation. The cleaning brush 53 is applied with a cleaning bias voltage and electrically sucks and removes paper dust adhering to the photosensitive drum 27.

  The fixing unit 18 heat-fixes the toner on the sheet 3 while the sheet 3 passes between the heating roller 41 and the pressing roller 42, and then conveys the toner to the sheet discharge path 44 by the conveying roller 43. I have to. The paper 3 sent to the paper discharge path 44 is discharged onto a paper discharge tray 46 by a paper discharge roller 45.

(Vibration mirror and semiconductor laser)
1. FIG. 3 is an overall view of the vibration mirror 19. The oscillating mirror 19 includes a mirror vibrator 60 and a pair of electrodes (hereinafter referred to as “movable electrode 61 and fixed electrode 62”). The mirror vibrator 60 has a structure in which, for example, a circular mirror part 63 is disposed in a frame part 64, and a pair of support shaft parts 65 protruding from the mirror part 63 are connected to the frame part 64. . The mirror vibrator 60 is formed, for example, by processing a single semiconductor substrate (for example, a silicon wafer) by a micromachining technique such as etching or film formation.

  Each support shaft 65 is provided with a movable electrode 61 protruding in a comb shape. The movable electrode 61 is formed by depositing a conductive material on the support shaft portion 65. On the other hand, a fixed electrode 62 protruding in a comb shape is also provided on the frame part 64 side. The fixed electrode 62 is formed by evaporating a conductive material on the frame portion 64. Comb tips of the movable electrode 61 and the fixed electrode 62 are alternately arranged so as to mesh with each other with a predetermined interval.

  The vibration control unit 66 gives a pulsed drive signal S <b> 1 (voltage signal) between the movable electrode 61 and the fixed electrode 62. Specifically, the drive signal S1 is given to the movable electrode 61, while the fixed electrode 62 is grounded. Thereby, the mirror part 63 of the oscillating mirror 19 has an electrostatic force (attractive force or repulsive force) periodically generated between the movable electrode 61 and the fixed electrode 62 and a restoring force of the support shaft part 65 that is torsionally deformed by the electrostatic force. And vibrate. The vibration control unit 66 performs feedback control based on the time interval of the detection timing of the laser light L by the BD sensor 22 so that the vibration cycle and the amplitude of the vibration mirror 19 become predetermined constant values, respectively.

2. Light Source Unit FIG. 4 is a simplified diagram showing the optical path of laser light from the light source unit 20. Note that reference numeral 73 in the figure denotes a reflection mirror (not shown in FIG. 2), which plays a role of reflecting the laser light L that has passed through the optical system 21 from the vibration mirror 19 and guiding it onto the photosensitive drum 27. The laser control unit 67 controls the light source unit 20 on and off. Further, the operation unit 68 (an example of a setting unit) plays a role of switching the setting between “image quality priority mode” and “speed priority mode” by a user operation.

  The light source unit 20 includes a first light source unit 70 (an example of a first emission unit) and a second light source unit 71 (an example of a second emission unit). The first light source unit 70 and the second light source unit 71 are each composed of a laser diode and a coupling lens, and are arranged side by side along the vibration rotation axis direction (the depth direction in FIG. 2) of the vibration mirror 19. As the light source unit, a laser array having two light emitting points may be used. In this case, the light emitting points are examples of the first emission means and the second emission means, respectively.

  With such a configuration, when the light source unit 70 and the light source unit 71 are turned on at the same time, the irradiation point P1 of the first laser beam L1 and the second laser beam L2 on the surface of the photosensitive drum 27 as shown in FIG. , P2 substantially coincide with each other in the main scanning direction (rotational axis direction of the photosensitive drum 27) and deviate by a predetermined distance M in the sub-scanning direction (rotational direction of the photosensitive drum 27).

3. Control by Laser Control Unit A laser control unit 67 (an example of a control unit) controls on / off of the light source unit 70 and the light source unit 71, and performs scanning with the first laser beam L1 and scanning with the second laser beam L2, which have different scanning directions. Thus, one scanning line is formed on the photosensitive drum 27. In other words, one scanning line is formed on the photosensitive drum 27 by scanning in the forward direction using one of the first laser light L1 and the second laser light L2 and scanning in the backward direction using the other laser light. Let

  This will be specifically described below. FIG. 5 is a diagram showing the relationship between the rotation angle of the oscillating mirror and the scanning locus of the laser light L (L1, L2). 5 are scanning trajectories of the laser beams L1 and L2 when the oscillating mirror 19 is vibrated while both the light source unit 70 and the light source unit 71 are always on. The solid black line is a miracle when the light source unit 70 is turned on and scanning (exposure) with the first laser light L1 is actually performed. A solid white line is a miracle when the light source unit 71 is turned on and scanning (exposure) with the second laser light L2 is actually performed.

  When the light source unit 70 and the light source unit 71 are turned on and the oscillating mirror 19 is oscillated, as shown in FIG. Inclined to the lower right of the paper with respect to the scanning direction, and tilted to the lower left of the paper with respect to the main scanning direction in the backward path (the locus from the right to the left of the paper). In the present embodiment, the predetermined distance M (the shift amount of the laser beams L1 and L2 in the sub-scanning direction) is the sub-distance in which each laser beam L1 (L2) moves during one cycle of the vibrating operation of the vibrating mirror 19. The distance is set to about half of the moving distance in the scanning direction.

(1) Image Quality Priority Mode The laser control unit 67 receives a synchronization signal synchronized with the vibration of the vibration mirror 19 from the vibration control unit 66. When the “image quality priority mode” is set, the laser control unit 67 executes the following first control. When the exposure to the photosensitive drum 27 is started, first, only the light source unit 71 is turned on during the first half of the return path, and both the light source unit 70 and the light source unit 71 are turned off during the second half of the return path. As a result, the scanning Y1 is performed on the photosensitive drum 27 by the second laser light L2.

  Next, the light source unit 70 and the light source unit 71 are turned on in the movement period of the first half of the forward path, and both the light source unit 70 and the light source unit 71 are turned off in the movement period of the second half of the forward path. Thereby, the scanning X2 by the first laser beam L1 and the scanning Y2 by the second laser beam L2 are performed on the photosensitive drum 27. Subsequently, the light source unit 70 and the light source unit 71 are turned on during the first half of the return path, and both the light source unit 70 and the light source unit 71 are turned off during the second half of the return path. Thereby, the scanning X3 by the first laser beam L1 and the scanning Y3 by the second laser beam L2 are performed on the photosensitive drum 27. Similarly, scans X4, Y4, X5. . . Are made sequentially.

  As a result of the first control described above, as shown in FIG. 5, a plurality of scanning lines R (lines formed by connecting a black solid line and a white solid line in FIG. 5) are formed. Each scanning line R is formed by scanning with the first laser light L1 and scanning with the second laser light L2, and the scanning direction of the scanning with the first laser light L1 and the scanning with the second laser light L2 is the forward path. The direction and the return direction are opposite to each other. In the plurality of scanning lines R formed in this way, the intervals between the scanning lines R adjacent in the sub scanning direction are uniform over the entire length in the main scanning direction. Therefore, spots (dots) by the laser beams L1 and L2 can be formed in the print region E with a uniform density over the entire length in the main scanning direction.

(2) Speed Priority Mode The laser controller 67 executes the following second control when the “speed priority mode” is set. FIG. 6 is a diagram showing the relationship between the rotation angle of the vibrating mirror and the scanning trajectory of the laser beam L (L1, L2) in the speed priority mode. In the speed priority mode, each scanning line R is formed by only one of scanning by the first laser beam L1 and scanning by the second laser beam L2. In addition, two scanning lines R are simultaneously formed by scanning with the first laser beam L1 and scanning with the second laser beam L2. Specifically, the first and third scanning lines R from the top in FIG. 6 are simultaneously formed by scanning X1 ′ using the first laser light L1 and scanning Y1 ′ using the second laser light L2, and then the second scanning line R1. And the fourth scanning line R are simultaneously formed by scanning X2 ′ using the first laser beam L1 and scanning Y2 ′ using the second laser beam L2.

  Here, in the plurality of scanning lines R formed in the speed priority mode, the intervals between the scanning lines R adjacent in the sub-scanning direction are not uniform over the entire length in the main scanning direction. Therefore, a density difference can occur in the left-right direction in the main scanning direction as compared with the image quality priority mode. However, in the speed priority mode, one scanning line R is formed by only one of scanning by the first laser light L1 and scanning by the second laser light L2, and two scanning lines R are formed at the same time. Accordingly, the rotation speed of the photosensitive drum 27 and the conveyance speed of the paper 3 can be increased as compared with the image quality priority mode.

(Effect of this embodiment)
1. According to the present embodiment, one scanning line R is formed by scanning (X1, X2...) Using the first laser light 11 having different scanning directions and scanning (Y1, Y2...) Using the second laser light L2. The configuration is formed on the photosensitive drum 27. Thereby, compared with the conventional structure which forms one scanning line by the scanning of the light beam of the same scanning direction, the space | interval error of scanning lines can be suppressed, and the fall of exposure quality can be suppressed.

  2. In the above embodiment, in order to realize the scanning shown in FIG. 5, the laser control unit 67 uses the first laser light on one side (left side in FIG. 5) with respect to the central position O in the sub-scanning direction of the photosensitive drum 27. Scanning in the forward direction by L1 and scanning in the forward direction by the second laser light L2 are alternately executed for each scanning line R. On the other side (right side in FIG. 5), scanning in the backward direction using the first laser light L1 and scanning in the backward direction using the second laser light L2 are alternately performed for each scanning line R. With such control, the laser control unit 67 only needs to repeatedly execute a predetermined on / off pattern for the light source unit 70 and the light source unit 71, and the control content can be made relatively simple.

  3. Furthermore, if you want to expose with high quality, you can set the image quality priority mode to perform exposure with suppressed scanning distortion by executing the first control. If you want to prioritize high-speed exposure, set the speed priority mode. For example, it is possible to perform high-speed exposure in which a plurality of (two in the present embodiment) scanning lines R are simultaneously formed by the second control.

<Embodiment 2>
FIG. 7 shows a second embodiment. The difference from the embodiment is in the contents of the first control, and the other points are the same as in the first embodiment. Therefore, the same reference numerals as those in the first embodiment are given and the redundant description is omitted, and only different points will be described next.

  In FIG. 5 of the first embodiment, each scanning line R is bent at the joint. In addition, since the joints of all the scanning lines R are aligned on the central position O of the printing area, the distortion of the scanning lines R near the central position O may affect the image quality of the entire image.

  On the other hand, in the first control of the present embodiment, as shown in FIG. 7, scanning with the first laser beam 11 (X1, X2 ...) and scanning with the second laser beam L2 (Y1, Y2 ...). ) Are different for each scanning line R (A1, A2, A3...). For example, the laser controller 67 varies the joints of the scanning lines R with random numbers. According to this configuration, it is possible to suppress the influence of the seam portion in the entire image as compared with the case where the seam portion is the same between the adjacent scanning lines R.

<Embodiment 3>
8 and 9 show the third embodiment. The difference from the above embodiment lies in the arrangement posture of the optical system 21 and the scanning trajectory of the laser light L associated therewith, and the other points are the same as in the first embodiment. Therefore, the same reference numerals as those in the first embodiment are given and the redundant description is omitted, and only different points will be described next.

  In the first and second embodiments, each scanning line R is bent at the joint, and an arcuate distortion (so-called bow) is generated. On the other hand, in the present embodiment, the optical system 21 is inclined to cancel the bow-shaped distortion. Specifically, as shown in FIG. 8, the optical system 21 can form a scanning line on the surface to be scanned without distortion by laser light incident at a predetermined incident angle (see the one-dot chain line in FIG. 8). ). On the other hand, when the incident angle of the laser beam is changed, an arcuate distortion in which the central portion swells in one direction occurs in the scanning line on the surface to be scanned (see the solid line in the figure). Using this principle, the scanning line R on the photosensitive drum 27 by the first laser beam L1 and the second laser beam L2 is rotated in the rotation direction (moving direction) of the photosensitive drum 27 at the center portion in the main scanning direction rather than at both end portions. The optical system 21 is provided in an arrangement posture that is largely displaced in the opposite direction. As a result, as shown in FIG. 9, the arcuate distortion seen in FIGS. 5 and 7 is canceled by the arcuate distortion caused by the optical system 21, so that each scanning line R extends along the straight line in the main scanning direction. Can be made.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) “Optical scanning device” includes, for example, a laser scanning display device, a projector, and a scanner (image reading device) in addition to the scanner unit 16 provided in the laser printer 1 as in the above embodiment. It may be.

  (2) In the above embodiment, one scanning line R is formed by scanning with two laser beams, the first laser beam L1 and the second laser beam L2. However, the present invention is not limited to this. It may be formed by scanning with two or more laser beams L. For example, four light emitting elements are arranged at predetermined intervals in the light source unit, and four laser beams can be emitted in parallel from these light emitting elements. Then, by turning on and off these light emitting elements, one scanning line R is formed by scanning (X, Y, Z, W) with four laser beams (see FIG. 10).

  (3) In the third embodiment, the optical system 21 is tilted to cancel the bow-shaped distortion. However, an optical system different from the optical system 21 is inserted in the optical path of the laser beam to form the bow-shaped distortion. It may be configured to cancel the distortion.

The principal part side sectional view of the laser printer concerning one embodiment of the present invention. Schematic diagram showing the configuration of the scanner unit Overall view of vibrating mirror The perspective view which shows the optical path of a 1st laser beam and a 2nd laser beam Diagram showing the relationship between the rotation angle of the vibrating mirror and the scanning trajectory of the laser beam (image quality priority mode) Diagram showing the relationship between the rotation angle of the vibrating mirror and the scanning trajectory of the laser beam (speed priority mode) The figure which showed the relationship between the rotation angle of the vibration mirror in Embodiment 2, and the scanning trace of a laser beam (image quality priority mode) Schematic diagram showing the relationship between the orientation of the optical system 21 and bow distortion in the third embodiment. Diagram showing the relationship between the rotation angle of the vibrating mirror and the scanning trajectory of the laser beam (image quality priority mode) The figure which showed the relation between the rotation angle of the vibration mirror of the modification and the scanning locus of the laser beam (image quality priority mode) The figure which showed the relationship between the rotation angle of the vibration mirror in the conventional optical scanning device, and the scanning locus of a laser beam

1. Laser printer (printing device)
3. Paper (an example of print media)
5 ... Printing section 16 ... Scanner section (optical scanning device)
19 ... Vibrating mirror 21 ... Optical system 27 ... Photosensitive drum (photoconductor)
67 ... Laser control unit (control means)
70 ... Light source section (first emitting means)
71 ... Light source part (second emitting means)
L1 ... first laser beam (first light beam)
L2 ... second laser beam (second light beam)
O ... Center position

Claims (6)

First emitting means for emitting a first light beam;
Second emitting means for emitting a second light beam;
A vibrating mirror that reciprocally scans the first light beam and the second light beam at different positions on the surface to be scanned;
The first emission means and the second emission means ,
In the printing area on the scanned surface, from on to off in the forward path by the vibrating mirror, from on to off in the middle of the return path by the vibrating mirror,
Or
In the printing area, from off to on during the forward path by the vibrating mirror, from off to on during the backward path by the vibrating mirror ,
An optical scanning device comprising: control means for forming a part or all of one scanning line on the surface to be scanned by scanning with the first light beam and scanning with the second light beam, the scanning directions of which are different from each other. The optical scanning device according to claim 1,
The control means performs scanning in the forward direction by the first light beam and scanning in the forward direction by the second light beam on one side of the one scanning line with the central position in the sub-scanning direction as a boundary on the surface to be scanned. An optical scanning device that is alternately executed every time, and on the other side, scanning in the backward direction by the first light beam and scanning in the backward direction by the second light beam are alternately executed for each scanning line. . The optical scanning device according to claim 1 or 2,
The optical scanning device in which a joint portion between the scanning with the one light beam and the scanning with the other light beam is different in at least adjacent scanning lines in the main scanning direction in the one scanning line. The optical scanning device according to any one of claims 1 to 3,
It is provided in the optical path between the vibrating mirror and the surface to be scanned, and the center of the image in the main scanning direction of the image by the first light beam and the second light beam moves from the both ends rather than both ends. An optical scanning device including an optical system that is largely displaced in a direction opposite to the direction. The optical scanning device according to any one of claims 1 to 4,
Setting means for setting the image quality priority mode and the speed priority mode is provided,
Wherein, when the image quality priority mode is set, the portion of one scanning line on the surface to be scanned by the scanning by the scanning direction is different from the first light beam and said second light beam with each other or If the speed priority mode is set when the first control for forming all of them is performed and the speed priority mode is set, the second control for simultaneously forming separate scanning lines by scanning the first light beam and the second light beam is performed. An optical scanning device that is configured to execute. A photoconductor and an optical scanning device according to any one of claims 1 to 5 for exposing the photoconductor, forming an image on the exposed photoconductor, and printing the image on a print medium A printing apparatus comprising a printing unit for transferring to a printer.

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