JP5458827B2 - Beam pitch adjusting method, optical scanning device, and image forming apparatus - Google Patents

Description

  The present invention relates to a beam pitch adjusting method for an optical scanning device, an optical scanning device using the beam pitch adjusting method, a copier, a printer, a facsimile, a plotter, or a complex machine including the optical scanning device. In addition, a multi-color image forming device that forms a color image by superimposing a plurality of color toner images, or an optical scanning device is arranged in series in the main scanning direction, and the scanning area of the main scanning is divided The present invention relates to an image forming apparatus such as a color copying machine, a color facsimile, a color printer, a wide-width copying machine, and a wide-width printer.

An optical scanning device that scans a light beam from a light source with a deflecting means such as a rotary polygon mirror and forms an image on a surface to be scanned by an imaging optical system, and a copying machine using the optical scanning device as a latent image writing device An image forming apparatus such as a printer, a facsimile, a plotter, or a complex machine of these is known.
Among such image forming apparatuses, in a tandem multicolor image forming apparatus disclosed in, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-341273), a photosensitive drum corresponding to each color is transferred in the transfer direction of the transfer body. A color image is formed by superimposing and transferring a toner image formed at an image forming station of each color on a recording medium conveyed by a transfer body, and a color image can be formed in one pass. Therefore, speeding up is possible.

  On the other hand, a multi-beam scanning device has been proposed as means for speeding up the optical scanning device. The multi-beam scanning device can scan a plurality of beams at once and simultaneously record a plurality of adjacent lines, and can increase the speed without increasing the rotation speed of the polygon scanner as a deflecting unit.

  Further, Patent Document 2 (Japanese Patent Application Laid-Open No. 2003- 211728) proposes a method of simultaneously forming a plurality of lines by collectively scanning using a two-dimensional array element (surface emitting semiconductor laser array: VCSEL). ing. By using a two-dimensional array element, the number of light emission sources can be increased to several tens of beams or more, so that the sub-scanning pitch on the photoconductor can be increased by forming a unit pixel in a matrix configuration of n × n dots. The recording density can be reduced to 1 / n, and higher-definition image recording can be performed.

  A light beam emitted from such a two-dimensional array element is shaped by a coupling optical system, then deflected and scanned by a polygon scanner, and a beam spot shape is created on the surface to be scanned through the imaging optical system. Scanned. The beam pitch of these plural beams is adjusted by the γ rotation of the light source unit, and the adjustment state is monitored by a two-dimensional sensor.

In general, the writing optical system has different main scanning magnification and sub-scanning magnification. For example, when a light source having a pitch of 0.4 mm in the main and sub is passed through an optical system having a main scanning magnification of 4 times and a sub scanning magnification of 1 times, the beam spot pitch is 1.6 mm in main and 0.4 mm in sub. It becomes.
When trying to adjust the sub-scanning pitch with a resolution of 1 μm with this optical system,
tan ⁻¹ (0.001 / 1.6) = 0.035 ° = 2.1 ′
Therefore, adjustment by assembly was impossible.

Also, because the main scanning magnification and the sub-scanning magnification are different,
(1) The pitch shifts due to the shift in the γ direction of the two-dimensional sensor.
(2) Even if the adjacent beam pitches in the sub-scanning direction are adjusted, the total (farthest) beam pitch does not match.
There is a problem.
Further, even when the pitch adjustment is performed by aligning the X direction of the two-dimensional sensor with the scanning line, there is a problem that the scanning line is inclined due to the image height and the adjustment pitch varies depending on the image height.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a beam pitch adjusting method capable of reducing a beam pitch detection error and adjusting a beam pitch to a predetermined pitch. It is another object of the present invention to provide an optical scanning apparatus using the beam pitch adjusting method and an image forming apparatus including the optical scanning apparatus.

In order to achieve the above object, the present invention employs the following solutions.
The first solving means of the present invention is a beam pitch adjusting method for an optical scanning device in which a light beam from a light source having a plurality of light emitting portions is scanned by a deflecting means, and an image is formed on a scanned surface by an imaging optical system. A two-dimensional sensor optically disposed at least at the same position as the surface to be scanned; means for emitting a light source at at least two points in the main scanning direction in the two-dimensional sensor; and incident on the two-dimensional sensor Means for calculating the position of the beam spot and means for rotating the two-dimensional sensor around the optical axis direction, and the lighting timing of the light beam so that the scanning line is aligned with the horizontal direction of the two-dimensional sensor. And the beam spot detection position between at least two points in the main scanning direction in the two-dimensional sensor is measured, and the coordinates of the beam spot detection position in the sub-scanning direction are substantially equal at least at two points. Comprising the step of rotating adjusting urchin said two-dimensional sensor,
The beam pitch in the sub-scanning direction between the light emitting units is measured by monitoring with the two-dimensional sensor, and the beam pitch between the light emitting units is adjusted (Claim 1).

The second solving means of the present invention scans a light beam from a light source unit having a light source having a plurality of light emitting portions arranged two-dimensionally by a deflecting means, and forms an image on a surface to be scanned by an imaging optical system. In the beam pitch adjusting method of the optical scanning device,
A two-dimensional sensor disposed at least at the same optical position as the surface to be scanned; means for emitting a light source at at least two points in the main scanning direction in the two-dimensional sensor; and a beam spot incident on the two-dimensional sensor And means for rotating the two-dimensional sensor about the optical axis direction, and changing the lighting timing of the light beam so that the scanning line is aligned with the horizontal direction of the two-dimensional sensor. The beam spot detection position between at least two points in the main scanning direction in the two-dimensional sensor is measured, and the coordinates of the beam spot detection position in the sub-scanning direction are substantially equal at least at two points. Adjusting the rotation of the beam, and measuring the beam pitch in the sub-scanning direction between the light emitting units by monitoring with the two-dimensional sensor, the beam pitch between the light emitting units With use of the beam pitch adjusting method for adjusting,
Means for rotating the light source unit about the optical axis direction and means for changing the optical magnification in the sub-scanning direction , and determines whether or not the sub-scanning beam pitch is a predetermined pitch; adjust the sub-scanning direction of the beam pitch between the light emitting portion adjacent by rotating the light source unit when not, further varying the sub-scanning direction of the optical magnification between the light emitting portion farthest sub The beam pitch in the scanning direction is adjusted (claim 2).

According to a third solving means of the present invention, in the beam pitch adjusting method of the first or second solving means, the two-dimensional sensor is moved in the main scanning direction at a plurality of image heights, and the inclination of the scanning line at the image height is obtained. Is calculated from the original beam pitch in the sub-scanning direction and the inclination in the scanning line so that the variation in beam pitch between the image heights in the sub-scanning direction due to the inclination of the scanning line at each image height is minimized. The pitch is adjusted to a target value as an average value of the beam pitch in the sub-scanning direction at each image height .

  According to a fourth aspect of the present invention, there is provided an optical scanning device in which a light beam from a light source having a plurality of light emitting units is scanned by a deflecting unit and formed on a surface to be scanned by an imaging optical system. The pitch adjustment is performed by the beam pitch adjustment method of any one of the three solutions (claim 4).

A fifth solving means of the present invention is an image forming apparatus, comprising the optical scanning device of the fourth solving means, wherein the optical scanning device forms an electrostatic latent image on an image carrier, and The image is obtained by developing the electrostatic latent image with toner and transferring it to a sheet-like recording medium.
According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the optical scanning device according to the fourth aspect, wherein the optical scanning device forms an electrostatic latent image on a plurality of image carriers. In addition, the electrostatic latent image is developed with a different color toner for each image carrier, and a toner image formed on each image carrier is supported on a sheet-like recording medium or an intermediate transfer member. In addition, a color image is obtained by transferring the images one after the other (claim 6).

In the beam pitch adjusting method of the first solving means, the light source is caused to emit light at least at two points in the main scanning direction in the two-dimensional sensor, and at least two-dimensional sensors arranged optically at the same position as the surface to be scanned. Means for calculating the position of the beam spot incident on the two-dimensional sensor, and means for rotating the two-dimensional sensor around the optical axis direction, the scanning line being aligned with the horizontal direction of the two-dimensional sensor. As described above, by changing the lighting timing of the light beam, the beam spot detection position between at least two points in the main scanning direction in the two-dimensional sensor is measured, and the coordinates of the beam spot detection position in the sub-scanning direction are at least 2. comprising the step of rotating adjusting the two-dimensional sensor so as to be substantially equal at the point, the sub-scanning direction of the beam between the light emitting portion by monitoring by the two-dimensional sensor The pitch was measured, by adjusting the beam pitch between the light emitting portion, when adjusting the beam pitch to move the plurality image height, the horizontal direction of the two-dimensional sensor, the main scanning line of each image height for sensing Since adjustment is performed in the same direction, a beam pitch detection error due to rotation of the two-dimensional sensor can be reduced.

In the beam pitch adjusting method of the second solving means, a light beam from a light source unit having a light source having a plurality of light emitting portions arranged two-dimensionally is scanned by a deflecting means, and is connected to a scanned surface by an imaging optical system. In the beam pitch adjusting method of an optical scanning device for imaging, a light source is caused to emit light at least at two points in the main scanning direction within the two-dimensional sensor, and at least two-dimensional sensors disposed at the same optical position as the surface to be scanned Means for calculating the position of the beam spot incident on the two-dimensional sensor, and means for rotating the two-dimensional sensor around the optical axis direction, the scanning line being aligned with the horizontal direction of the two-dimensional sensor. As described above, by changing the lighting timing of the light beam, the beam spot detection position between at least two points in the main scanning direction in the two-dimensional sensor is measured, and the beam spot detection is performed. A step of rotating and adjusting the two-dimensional sensor so that the coordinates of the position in the sub-scanning direction are substantially equal at least at two points, and the beam pitch in the sub-scanning direction between the light emitting units is monitored by the two-dimensional sensor. And a means for adjusting the beam pitch between the light emitting sections, a means for rotating the light source unit around the optical axis direction, and a means for varying the optical magnification in the sub-scanning direction. provided, it is determined whether the sub-scanning beam pitch is at a prescribed pitch, adjusting the sub-scanning direction of the beam pitch between the light emitting portion adjacent by the determination result rotating the light source unit in the case of not further varying the sub-scanning direction of the optical magnification by adjusting the sub-scanning direction of the beam pitch between the light emitting portion that is most distant, main and sub magnification writing optical system Beam pitch between even different channels can substantially be uniformly adjusted to a predetermined pitch.

In the beam pitch adjusting method of the third solving means, in addition to the effects of the first or second solving means, the two-dimensional sensor is moved in the main scanning direction at a plurality of image heights, and the inclination of the scanning line at the image height is obtained. Is calculated from the original beam pitch in the sub-scanning direction and the inclination in the scanning line so that the variation in beam pitch between the image heights in the sub-scanning direction due to the inclination of the scanning line at each image height is minimized. By adjusting the pitch to the target value as the average value of the beam pitch in the sub-scanning direction at each image height and maintaining the pitch balance between the image heights, an extreme pitch difference between the image heights can be eliminated.

  In the optical scanning device of the fourth solving means, the pitch is adjusted by the beam pitch adjusting method of any one of the first to third solving means, so that an extreme pitch difference due to the image height is eliminated and stable. Images can be obtained.

  The image forming apparatus of the fifth solving means includes the optical scanning device of the fourth solving means, and forms an electrostatic latent image on the image carrier by the optical scanning device, and the electrostatic latent image is formed with toner. By developing and transferring to a sheet-like recording medium, a stable high-quality image can be obtained.

  The image forming apparatus of the sixth solving means includes the optical scanning device of the fourth solving means, and forms an electrostatic latent image on a plurality of image carriers by the optical scanning device, and By developing with different color toners for each image carrier, and sequentially transferring the toner images formed on each image carrier to a sheet-like recording medium carried on the transfer member or an intermediate transfer member. Thus, a stable and high-quality color image with little color shift can be obtained.

It is a figure which shows one Example of this invention, Comprising: It is a figure which shows the structural example of an optical scanning device, and the example of the arrangement position of a two-dimensional sensor. It is a perspective view which shows an example of a light source unit. It is a figure which shows an example of the light beam projected on the to-be-scanned surface. It is explanatory drawing of the adjustment method of the subscanning pitch by a two-dimensional sensor. It is explanatory drawing of the measuring method of inclination (theta) of the scanning line by a two-dimensional sensor. It is a flowchart which shows the process of pitch adjustment. It is explanatory drawing of the bending of a scanning line, and the adjustment method of a scanning line pitch. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. It is a schematic block diagram of the image forming apparatus which shows another Example of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a diagram showing an embodiment of the present invention, and is a diagram showing a configuration example of an optical scanning device and an example of an arrangement position of a two-dimensional sensor.
A light beam emitted from a light source (for example, a light source composed of a two-dimensional array element (surface emitting semiconductor laser array: VCSEL)) 101 having a plurality of light emitting units constituting the light source unit 104 is emitted through a coupling lens 102 and an aperture 103. Then, it is collectively scanned by an optical deflector (two-stage polygon mirror in the illustrated example) 107 that is a deflecting unit through the zoom lens 105 and the cylindrical lens 106. This scanning beam forms an image of the beam spot on the scanned surface 110 through an imaging optical system such as the scanning lenses 108a and 108b and the folding mirrors 109a to 109c. Normally, the scanned surface 110 is a photoconductor, but in this embodiment, two-dimensional sensors (CCD, CMOS sensors, etc.) 112a to 112c are optically located at the same position as the scanned surface as a beam pitch adjustment monitor. It is arranged. The two-dimensional sensors 112a to 112c can be moved by a stage or the like (not shown). Although three two-dimensional sensors 112a to 112c are arranged in FIG. 1, one two-dimensional sensor placed on the stage may be moved in the scanning direction (main scanning direction). In this embodiment, the zoom lens 105 is used as means for adjusting the optical magnification in the sub-scanning direction (a direction orthogonal to the main scanning direction on the surface to be scanned). However, for example, a prism or the like may be used.

  FIG. 2 is a perspective view showing an example of the light source unit 104. A light source 101 having a plurality of light emitting units arranged two-dimensionally is mounted on a printed board. The light source unit 104 is formed by holding the coupling lens 102 and the aperture 103 in an aluminum or resin housing to which the printed board is fixed. The light beam emitted from the light source 101 is emitted from the aperture 103 through the coupling lens 102. The light source unit 104 rotates the emitted light beam around the optical axis direction (referred to as γ rotation) by moving the arms at both ends up and down by a drive mechanism (not shown) composed of a motor, gear, cam, link and the like. It can be made to.

  FIG. 3 shows an example of a light beam projected on the scanned surface 110. In this embodiment, the light source 101 has nine light emitting units arranged two-dimensionally, and the number of light beams projected on the scanned surface 110 is nine. In order to form a latent image uniformly on the surface to be scanned with these light beams, the beam pitches of adjacent channels of these beams need to be aligned to a predetermined pitch. For this purpose, the adjacent pitch is adjusted by rotating the outgoing beam from the light source unit 104 by γ rotation in the optical axis direction. However, the optical magnification of the writing optical system is not the same in the main and sub scanning directions. Therefore, even if the sub-scanning pitch between 2ch and 3ch is adjusted to a predetermined pitch, the sub-scanning pitch between 3ch and 4ch does not become a predetermined pitch.

Therefore, in this embodiment, as shown in FIG. 1, these pitch adjustments are performed by monitoring with the two-dimensional sensor 112 (112a to 112c). FIG. 6 is a flowchart showing the pitch adjustment process.
First, the horizontal direction of the two-dimensional sensor 112 is matched with the scanning line in the main scanning direction of the light beam (S1). When the optical magnification differs in the main and sub scanning directions, this adjustment is performed because the sub scanning pitch changes due to rotation (γ rotation) about the optical axis of the two-dimensional sensor 112. The adjustment method will be described with reference to FIG.

In FIG. 4, the area having a square grid is the screen (light receiving area) of the two-dimensional sensor, the horizontal direction (X direction) of the paper is the main scanning direction of the light beam, and the vertical direction (Y direction) of the paper is the sub-scanning. Direction.
As shown in FIG. 4, the light emitting unit of an arbitrary channel is turned on at two points on both the left and right sides of the two-dimensional sensor 112, and the coordinates in the sub-scanning direction (Y coordinate in FIG. 4) detected at the positions of these two ends are approximately. The two-dimensional sensor 112 is adjusted by rotating it by γ so as to be the same.

  Next, the beam pitch in the sub-scanning direction of the adjacent channel is measured (S2). In this measurement method, for example, in FIG. 3, ch2 and ch3 are simultaneously turned on in the sensor region of the two-dimensional sensor 112, and the difference between the Y coordinates is set to the sub-scanning beam pitch p2-3 of ch2 and ch3. Since the sensor array pitch of the two-dimensional sensor 112 is as coarse as several microns, the detected beam position may be obtained, for example, from the beam intensity distribution, and the coordinate position may be used as the beam position. Further, the light emitting sections are turned on channel by channel in the sensor area for ch2 and ch3, the respective detection beam position coordinates are obtained, and the difference between the Y coordinates may be used as the sub-scanning beam pitch p2-3 for ch2 and ch3. . In this case, if the light emitting portions of ch2 and ch3 are turned on on the same polygon mirror surface, the influence of the surface tilt of the polygon mirror can be reduced. In either case, the measurement is performed a plurality of times and the average is taken, so that the measurement variation can be leveled and the accuracy can be improved.

It is determined whether the measured sub-scanning beam pitch p2-3 of ch2 and ch3 is a predetermined pitch (S3).
If the predetermined pitch does not appear, the light source unit 104 is rotated by γ (S4). In this way, S2 to S4 are repeated, and the sub-scanning beam pitch p2-3 of ch2 and ch3 is adjusted to a predetermined pitch.
When p2-3 reaches a predetermined pitch, the sub-scanning beam pitch p1-9 of channels ch1 and ch9 that are farthest in the sub-scanning direction is measured by the same method as the pitches of ch2 and ch3 (S5). .

In general, since the optical magnifications in the main and sub-scanning directions are different, by the γ rotation of the light source unit 104,
p1-9 ≠ 8 × p2-3
Therefore, the beam pitch between the channels is not aligned.
Therefore, it is determined whether the sub-scanning beam pitch p1-9 of ch1 and ch9 is a predetermined pitch (S6). If the predetermined pitch does not appear, the zoom lens 105 adjusts the magnification (S7). Then, returning to S3, the pitch of the adjacent channel is adjusted again. If the predetermined pitch is obtained in S6, the pitch adjustment is terminated.
When such pitch adjustment is performed, the scan line 111 generally bends as shown in FIG. 7. Therefore, the beam pitch is adjusted between the pitch-adjusted position in the main scanning direction (image height) and other image heights. Is different. For this reason, it is necessary to level the pitch at each image height.

In FIG. 7, when the scanning line bends at the image heights a ₁ , a ₀ , and a ₂ are θ ₁ , θ ₀ , θ ₂ , and the original pitch is P, the target scanning line pitch P ′ is expressed by, for example, the following equation: It may be adjusted so that
P ′ = P (cos θ ₁ + cos θ ₀ + cos θ ₂ ) / 3
At that time, the image heights a ₁ , a ₀ , a ₂ and the scanning line pitches P ₁ , P ₀ , P ₂ are respectively
P ₁ = P ′ / cos θ ₁
P ₀ = P ′ / cos θ ₀
P ₂ = P ′ / cos θ ₂
It becomes.

A method of measuring the inclination θ of the scanning line 111 will be described with reference to FIG.
In FIG. 5, the area having a square grid is the screen (light receiving area) of the two-dimensional sensor, the horizontal direction (X direction) of the paper is the main scanning direction of the light beam, and the vertical direction (Y direction) of the paper is the sub-scanning. Direction.
First, the position Y1 of the light beam in the Y direction (sub-scanning direction) is measured at the left end of the screen of the two-dimensional sensor 112. Next, the light beam is moved ΔX to the right end of the two-dimensional sensor 112 without changing the light emission timing, and the position Y2 of the light beam in the Y direction is measured. Since the scanning line 111 should be aligned with the horizontal direction of the two-dimensional sensor 112 in S1 of FIG. 6, the inclination θ of the scanning line is expressed by the following equation.
θ = tan ⁻¹ ((Y2−Y1) / ΔX)

  Therefore, the inclination θ at the image height of the scanning line is calculated from the above formula, and the pitch is adjusted to a target value that minimizes the pitch variation between the image heights due to the scanning line inclination of each image height. By taking a pitch balance between them, it is possible to eliminate an extreme pitch difference between image heights.

  As described above, in the beam pitch adjusting method of this embodiment, the two-dimensional sensor 112 (112a to 112c) disposed at least at the same optical position as the surface to be scanned 110, and the main scanning direction in the two-dimensional sensor Means for emitting a light source at at least two points (light source driving circuit not shown), means for calculating the position of a beam spot incident on the two-dimensional sensor 112 (microcomputer etc. of a control unit not shown), and a two-dimensional sensor Means for rotating the light 112 about the optical axis direction (stage not shown) and the like within the two-dimensional sensor by changing the lighting timing of the light beam so that the scanning line matches the horizontal direction of the two-dimensional sensor 112. The beam spot detection position between at least two points in the main scanning direction (X direction in FIG. 4) is measured, and the coordinates of the beam spot detection position in the sub-scanning direction (see FIG. The two-dimensional sensor 112 is rotated in such a way that the Y coordinate position of the two-dimensional sensor 112 is substantially equivalent to at least two points, so that the horizontal direction of the two-dimensional sensor 112 is sensed when moving a plurality of image heights and adjusting the beam pitch. Therefore, the beam pitch detection error due to the rotation of the two-dimensional sensor 112 can be reduced.

  In this embodiment, the light source unit 104 is rotated by γ about the optical axis direction (a driving mechanism (not shown) including a motor, a gear, a cam, a link, etc.) and the optical magnification in the sub-scanning direction is varied. (For example, a zoom lens) 105, and the light source unit 104 is rotated by γ to adjust the sub-scanning beam pitch of the adjacent light emitting units, and the optical magnification in the sub-scanning direction is changed by the zoom lens 105, and is most distant By adjusting the beam pitch between the light emitting sections, the beam pitch between the channels can be adjusted substantially uniformly to a predetermined pitch even if the magnification in the main and sub scanning directions of the writing optical system is different.

Further, in this embodiment, there are provided means for moving the two-dimensional sensor 112 in the main scanning direction at a plurality of image heights to calculate the inclination of the scanning line at the image height (such as a microcomputer of a control unit not shown), Eliminating extreme pitch differences between image heights by adjusting the pitch to a target value that minimizes the variation in pitch between image heights due to the inclination of the scan line of the image height, and balancing the pitch between image heights. Can do.
In the optical scanning device 100 according to the present embodiment, the pitch adjustment is performed by the beam pitch adjustment method as described above, so that a stable image can be obtained without an extreme pitch difference between image heights.

Next, an embodiment of an image forming apparatus provided with an optical scanning device whose pitch is adjusted by the beam pitch adjusting method as described above will be described.
FIG. 8 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention, and shows a configuration example of a laser printer.
This laser printer includes an optical scanning device 100, a photosensitive drum 130 as an image carrier, a charging device (charging charger, charging roller, etc.) 131, a developing device 132 having a developing roller 132a, a transfer device (transfer charger, transfer roller, etc.). 133, a static elimination unit 134, a cleaning device (cleaning blade, etc.) 135, a toner cartridge 136, a paper feed roller 137, a paper feed tray 138, a registration roller pair 139, a fixing device (fixing roller pair, etc.) 141, a paper discharge roller 142, and A paper discharge tray 143 is provided.

  The charging device 131, the developing roller 132 a of the developing device 132, the transfer device 133, the charge eliminating unit 134, and the cleaning device (cleaning blade or the like) 135 are arranged in the vicinity of the surface of the photosensitive drum 130. Then, with respect to the rotation direction of the photosensitive drum 130, the charging device 131, the developing device 132, the transfer device 133, the static elimination unit 134, and the cleaning device 135 are arranged in this order.

A photosensitive layer is formed on the surface of the photosensitive drum 130. Here, the photosensitive drum 130 rotates clockwise (in the direction of the arrow in the drawing) within the plane in FIG.
The charging device 131 uniformly charges the surface of the photosensitive drum 130.
The optical scanning device 100 irradiates the surface of the photosensitive drum 130 charged by the charging device 131 with light modulated based on image information from a host device (for example, a personal computer). As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 130 on the surface of the photosensitive drum 130. The latent image formed here moves in the direction of the developing roller 132 a as the photosensitive drum 130 rotates. The configuration of the optical scanning device 100 and the beam pitch adjusting method are as described above.

The toner cartridge 136 stores toner, and the toner is supplied to the developing device 132.
The developing roller 132a of the developing device 132 causes the toner supplied from the toner cartridge 136 to adhere to the electrostatic latent image formed on the surface of the photosensitive drum 130 to visualize the image information. Here, the latent image to which the toner is attached (hereinafter, also referred to as “toner image” for convenience) moves in the direction of the transfer device 133 as the photosensitive drum 130 rotates.

  The paper feed tray 138 stores a recording paper 140 that is a sheet-like recording medium. A paper feed roller 137 is disposed in the vicinity of the paper feed tray 138, and the paper feed roller 137 takes out the recording paper 140 one by one from the paper feed tray 138 and conveys it to the registration roller pair 139. The registration roller pair 139 is disposed in the vicinity of the transfer device 133, temporarily holds the recording paper 140 taken out by the paper feed roller 137, and aligns the recording paper 140 with the rotation of the photosensitive drum 130. It is sent out toward the gap between 130 and the transfer device 133.

A voltage having a polarity opposite to that of the toner is applied to the transfer device 133 in order to electrically attract the toner on the surface of the photosensitive drum 130 to the recording paper 140. With this voltage, the toner image on the surface of the photosensitive drum 130 is transferred to the recording paper 140. Here, the recording paper 140 onto which the toner image has been transferred is sent to the fixing device 141.
In the fixing device 141, heat and pressure are applied to the recording paper 140 by a pair of fixing rollers (a heating roller and a pressure roller), whereby the toner image is fixed on the recording paper 140. Here, the recording paper 140 on which the toner image is fixed is sent to the paper discharge tray 143 via the paper discharge roller 142 and is sequentially stacked on the paper discharge tray 143.

The neutralization unit 134 neutralizes the surface of the photosensitive drum 130 after the toner image is transferred.
The cleaning device 135 removes toner (residual toner) remaining on the surface of the photosensitive drum 130. The removed residual toner is returned to the developing device 132 by a recycle mechanism (not shown) and is used again. The surface of the photosensitive drum 130 from which the residual toner has been removed returns to the position of the charging device 131 and enters a standby state for the next image forming process.

  FIG. 8 shows a configuration example of a laser printer as an example of an image forming apparatus. However, if an image reading unit (image scanner) is installed on the upper part of the image forming apparatus, it can be used as a digital copying machine. By providing a communication function and connecting to a communication line (telephone line, optical line, etc.), it can be used as a facsimile or a digital multi-function peripheral.

  The image forming apparatus having the above-described configuration includes the optical scanning device 100 in which the pitch is adjusted by the beam pitch adjusting method as described above. A stable high-quality image can be obtained by forming an electrostatic latent image, developing the electrostatic latent image with the toner of the developing device 132, and transferring it to the recording paper 140.

Next, FIG. 9 is a schematic configuration diagram of an image forming apparatus showing another embodiment of the present invention, showing an example of the configuration of a tandem type color printer having a plurality of photosensitive drums corresponding to color images. Yes.
The tandem type color printer includes a black (K) photosensitive drum 130K, a charging device 131K, a developing device 132K, a transfer device 133K, a cleaning device 135K, a cyan (C) photosensitive drum 130C, and a charging device. 131C, developing device 132C, transfer device 133C, and cleaning device 135C, magenta (M) photosensitive drum 130M, charging device 131M, developing device 132M, transfer device 133M, cleaning device 135M, and yellow (Y) Photosensitive drum 130Y, charging device 131Y, developing device 132Y, transfer device 133Y, and cleaning device 135Y, optical scanning device 1000, transfer belt 150 stretched between a plurality of rollers 151a and 151b, and sheet-like recording. Paper feed tray for storing media (recording paper) And 161, paper feed and conveyance means (the paper feed roller 162, separation roller 163, conveying rollers 164 and 165, a pair of registration rollers 166) and has a fixing device (fixing roller equal) 167.

In the case of this configuration example, the optical scanning device 1000 includes a light emitting unit for black, a light emitting unit for cyan, a light emitting unit for magenta, and a light emitting unit for yellow, and one light deflector (polygon mirror). Etc.), the light beams from the respective light emitting sections are distributed and scanned toward the respective photosensitive drums 130K to 130Y.
Then, the light from the black light emitting unit is irradiated to the photosensitive drum 130K through the black scanning imaging optical system, and the light from the cyan light emitting unit through the cyan scanning imaging optical system. The light from the light emitting unit for magenta is irradiated to the photosensitive drum 130C, the light from the light emitting unit for magenta is irradiated to the photosensitive drum 130M via the scanning imaging optical system for magenta, and the light from the light emitting unit for yellow is scanned. The photosensitive drum 130Y is irradiated through an image optical system.
In addition, it is good also as a structure provided with the optical scanning device 1000 as shown in FIG. 1 for every color.

  Each of the photosensitive drums 130K, 130C, 130M, and 130Y rotates clockwise (in the direction of the arrow in FIG. 9), and charging devices 131K, 131C, 131M, and 131Y, and developing devices 132K, 132C, 132M, and 132Y, respectively, in the order of rotation. Transfer devices 133K, 133C, 133M, and 133Y, and cleaning devices 135K, 135C, 135M, and 135Y are disposed. Each charging device 131K, 131C, 131M, 131Y uniformly charges the surface of the corresponding photosensitive drum 130K, 130C, 130M, 130Y. The surface of the photosensitive drum charged by the charging devices 131K, 131C, 131M, and 131Y is irradiated with light by the optical scanning device 1000, and electrostatic latent images corresponding to the respective colors are formed on the photosensitive drums 130K, 130C, 130M, and 130Y. It has come to be. The corresponding developing devices 132K, 132C, 132M, and 132Y form toner images of respective colors on the surface of the photosensitive drum. Further, the recording paper 161 is fed sheet by sheet by the sheet feeding roller 162 and the separation roller 163 from the sheet feeding tray 160 and conveyed onto the transfer belt 150 via the conveying rollers 164 and 165 and the registration roller pair 166. The transfer devices 133K, 133C, 133M, and 133Y corresponding to the photosensitive drums superimpose and transfer the toner images of the respective colors. The recording paper 161 onto which the toner image has been transferred is sent to the fixing device 167, and heat and pressure are applied to the recording paper 161 by a pair of fixing rollers (heating roller and pressure roller), whereby the toner image is transferred to the recording paper 161. Fixed on top. Here, the recording paper 161 on which the toner image is fixed is sent to a paper discharge tray (not shown) via a paper discharge roller (not shown) and is sequentially stacked on the paper discharge tray. On the other hand, the toner (residual toner) remaining on the surfaces of the photosensitive drums 130K, 130C, 130M, and 130Y after the toner image transfer is removed by the cleaning devices 135K, 135C, 135M, and 135Y.

FIG. 9 shows a configuration example of a tandem type color printer as an example of an image forming apparatus. However, if an image reading unit (image scanner) is installed on the upper part of the image forming apparatus, it can be used as a digital color copying machine. Further, by providing a communication function and connecting to a communication line (telephone line, optical line, etc.), it can be used as a color facsimile or a digital color multifunction peripheral.
In the example of FIG. 9, the toner images of the respective colors formed on the photosensitive drums 130K, 130C, 130M, and 130Y are directly transferred to the recording paper 161. However, the transfer belt 150 is an intermediate transfer member (intermediate transfer member). As the belt), the toner images of the respective colors formed on the respective photosensitive drums 130K, 130C, 130M, and 130Y are temporarily superimposed on the intermediate transfer belt to be primarily transferred to form a color toner image, and then the intermediate transfer belt The upper color toner image may be secondarily transferred onto the recording paper.

  In the color image forming apparatus having the above-described configuration, the present invention includes the optical scanning device 1000 whose pitch is adjusted by the beam pitch adjusting method as described above. , 130C, 130M, and 130Y, electrostatic latent images are formed, and the electrostatic latent images are developed with different color toners by developing devices 132K, 132C, 132M, and 132Y corresponding to the respective photosensitive drums. The toner images formed on the body drums 130K, 130C, 130M, and 130Y are transferred to the recording paper 161 (or the intermediate transfer belt) carried on the transfer belt 150 in an overlapping manner so that the color deviation is stable. A high-quality color image can be obtained.

  The above-described optical scanning device according to the present invention has an optical scanning device arranged in series in the main scanning direction in addition to the image forming device shown in FIG. 8 and the color image forming device shown in FIG. The present invention can be used in image forming apparatuses such as a color copying machine, a color facsimile, a color printer, a wide-width copying machine, and a wide-width printer that scan by dividing a scanning area.

DESCRIPTION OF SYMBOLS 100, 1000: Optical scanning device 101: Light source 102: Coupling lens 103: Aperture 104: Light source unit 105: Zoom lens 106: Cylindrical lens 107: Optical deflector (polygon mirror)
108a, 108b: Scanning lenses 109a, 109b, 109c: Folding mirror 110: Scanned surface 111: Scanning line 112 (112a, 112b, 112c): Two-dimensional sensor 130, 130K, 130C, 130M, 130Y: Photosensitive drum (image) Carrier)
131, 131K, 131C, 131M, 131Y: charging device 132, 132K, 132C, 132M, 132Y: developing device 133, 133K, 133C, 133M, 133Y: transfer device 134: static elimination unit 135, 135K, 135C, 135M, 135Y: Cleaning device 136: Toner cartridge 137, 162: Paper feed roller 138, 160: Paper feed tray 139, 166: Registration roller pair 141, 167: Fixing device 142: Paper discharge roller 143: Paper discharge tray 150: Transfer belt

JP 2002-341273 A JP 2003- 211728 A

Claims (6)

A beam pitch adjusting method of an optical scanning device that scans a light beam from a light source having a plurality of light emitting portions by a deflecting unit and forms an image on a scanned surface by an imaging optical system,
A two-dimensional sensor disposed at least at the same optical position as the surface to be scanned; means for emitting a light source at at least two points in the main scanning direction in the two-dimensional sensor; and a beam spot incident on the two-dimensional sensor And means for rotating the two-dimensional sensor about the optical axis direction, and changing the lighting timing of the light beam so that the scanning line is aligned with the horizontal direction of the two-dimensional sensor. The beam spot detection position between at least two points in the main scanning direction in the two-dimensional sensor is measured, and the coordinates of the beam spot detection position in the sub-scanning direction are substantially equal at least at two points. A step of adjusting the rotation ,
A beam pitch adjusting method comprising: measuring a beam pitch in the sub-scanning direction between the light emitting units by monitoring with the two-dimensional sensor, and adjusting the beam pitch between the light emitting units . In a beam pitch adjusting method of an optical scanning device that scans a light beam from a light source unit having a light source having a plurality of light emitting units arranged two-dimensionally by a deflecting unit and forms an image on a scanned surface by an imaging optical system,
A two-dimensional sensor disposed at least at the same optical position as the surface to be scanned; means for emitting a light source at at least two points in the main scanning direction in the two-dimensional sensor; and a beam spot incident on the two-dimensional sensor And means for rotating the two-dimensional sensor about the optical axis direction, and changing the lighting timing of the light beam so that the scanning line is aligned with the horizontal direction of the two-dimensional sensor. The beam spot detection position between at least two points in the main scanning direction in the two-dimensional sensor is measured, and the coordinates of the beam spot detection position in the sub-scanning direction are substantially equal at least at two points. Adjusting the rotation of the beam, and measuring the beam pitch in the sub-scanning direction between the light emitting units by monitoring with the two-dimensional sensor, the beam pitch between the light emitting units With use of the beam pitch adjusting method for adjusting,
A means for rotating the light source unit about the optical axis direction; and a means for changing the optical magnification in the sub-scanning direction, and determining whether or not the beam pitch in the sub-scanning direction is a predetermined pitch. If the result is negative, the light source unit is rotated to adjust the beam pitch in the sub-scanning direction between the adjacent light-emitting parts, and the optical magnification in the sub-scanning direction is varied to change the sub- light distance between the light-emitting parts farthest away. A beam pitch adjusting method comprising adjusting a beam pitch in a scanning direction . In the beam pitch adjusting method according to claim 1 or 2,
Means for moving the two-dimensional sensor in the main scanning direction at a plurality of image heights to calculate the inclination of the scanning line at the image height, and a beam in the sub-scanning direction between the image heights by the scanning line inclination of each image height. The pitch adjustment is performed to a target value as an average value of the beam pitch in the sub-scanning direction at each image height calculated from the original beam pitch in the sub-scanning direction and the inclination in the scanning line so as to minimize the pitch variation. The beam pitch adjustment method. In an optical scanning device that scans light beams from a plurality of light sources with a deflecting unit and forms an image on a scanned surface by an imaging optical system,
4. An optical scanning device characterized in that the pitch is adjusted by the beam pitch adjusting method according to claim 1.   5. An optical scanning device according to claim 4, wherein the electrostatic scanning image is formed on the image carrier by the optical scanning device, and the electrostatic latent image is developed with toner and transferred to a sheet-like recording medium. An image forming apparatus characterized in that an image is obtained.   5. An optical scanning device according to claim 4, wherein electrostatic latent images are formed on a plurality of image carriers by the optical scanning device, and the electrostatic latent images are developed with different color toners for each image carrier. The toner image formed on each image carrier is sequentially transferred to a sheet-like recording medium carried on the transfer member or an intermediate transfer member to obtain a color image. Image forming apparatus.

Images