JPH09211360A - Scanning optical device - Google Patents

Abstract

(57) An object of the present invention is to provide a scanning optical device capable of easily performing the work of adjusting the inclination or the like of the image plane. An opening (1) for drawing on a bottom surface of a case (1).
1) is formed, an adjustment opening (12) is formed on the side surface of the case (1), and light emitted from the scanning optical system is guided from the adjustment opening (12) to the outside of the case (1). did.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device for scanning a light beam in a laser printer or the like.

[0002]

2. Description of the Related Art In a high-definition scanning optical device, the allowable range of inclination and curvature of an image plane of light emitted from the scanning optical device is more severe than that of a normal scanning optical device. Therefore, at the time of manufacturing, it is common to assemble the scanning optical device as a single unit, and then finely adjust the inclination and the like of the lens in the scanning optical device while measuring the inclination and the curvature of the image plane.

Specifically, a stationary beam (a beam that does not perform scanning) is emitted from the scanning optical device, the beam diameter in the vicinity of the image plane is measured by a dedicated measuring device, and the measuring device is moved in the optical axis direction. By making measurements while
The position where the beam diameter is minimized, that is, the image formation position is obtained. Then, the inclination or curvature of the image forming surface is obtained from the data of the image forming positions measured at three points in the main scanning direction. Then, the fine adjustment such as the inclination of the lens is performed so that the image plane becomes a flat surface as designed. Therefore, this adjustment involves many measurements and requires a large number of man-hours.

[0004]

However, in a high-definition printer, the scanning optical systems are arranged on substantially the same plane, and the photosensitive drums are arranged at positions separated by a predetermined amount in the direction orthogonal to this plane. Is common. That is, the image planes are formed at positions separated in the direction orthogonal to the scanning optical devices arranged on the substantially same plane. Therefore, it is necessary to perform three-dimensional measurement many times on the scanning optical device, which causes a problem of poor work efficiency. Further, in recent years, printers have tended to increase in size with the increase in screen size, the scanning optical device has become larger, and the work space itself for the operator has a jig structure that is difficult to secure.

It is an object of the present invention to provide a scanning optical device that allows the operation of adjusting the inclination of the image plane in the scanning optical device to be easily performed.

[0006]

In order to solve the above problems, a scanning optical device according to the present invention comprises a case having two openings for guiding light emitted from the scanning optical system to the outside of the case.
One of the two openings is used for drawing, and the other opening is formed so as to guide the emitted light between the surfaces extending from the pair of surfaces. With this configuration, in addition to the drawing opening, an opening for guiding the emitted light is provided in substantially the same plane as the scanning optical device, so that adjustment work can be performed in substantially the same plane as the scanning optical device. It will be possible.

It should be noted that the drawing aperture may be configured to guide the emitted light to the outside of the surface extending from the pair of surfaces. Further, the other opening described above may be used as an adjustment opening. Further, by mounting a mirror between the adjustment aperture and the scanning optical system, the emitted light passes through the drawing aperture, and by removing the mirror, the emitted light passes through the adjustment aperture. You can also Further, the drawing opening may be provided on one of the pair of surfaces.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a scanning optical device according to the present invention will be described below. The scanning optical device shown as the embodiment is a multi-beam scanning optical device that simultaneously scans eight laser beams to simultaneously form eight scanning lines in one scan. First, the schematic configuration of the entire apparatus will be described.

FIG. 1 is a perspective view showing an embodiment of a scanning optical device, and FIG. 2 is a side view showing an embodiment of the scanning optical device together with a photosensitive drum. As shown in FIG. 1, the scanning optical device is configured by arranging a scanning optical system in a flat casing 1 having a substantially rectangular parallelepiped shape. The upper opening of the casing 1 is closed by the upper lid 2 when in use.

At the upper part of the casing 1 in the drawing, a connector portion 102 for receiving signals relating to image information is provided. A laser block support substrate 300 is provided adjacent to the connector 102, and a laser block 310 that holds the eight semiconductor lasers 101 that emit a light beam based on the above signals and the input ends of the optical fibers 120 face each other is provided on the support substrate 300. It is fixed. As a result, 8
The light flux is guided to one optical fiber 120.

The end surface 120 of the optical fiber 120 on the exit side
b is held by the fiber alignment block 130. The light flux from the exit end face 120b is a collimator lens 140, a half mirror 144, a dynamic prism 160, and the cylindrical lens 1 described later.
The light enters the polygon mirror 180 via 70. The polygon mirror 180 is rotationally driven by a polygon motor 371 (see FIG. 2) fixed to the casing,
It reflects and deflects the light flux that has entered the mirror surface. The light beam deflected by the polygon mirror 180 enters the fθ lens 190 which is an imaging lens. The light flux from the fθ lens 190 is reflected downward by the folding mirror 200 in the figure and forms an image on the photosensitive drum 210, which is the surface to be scanned, as shown in FIG.

Here, in order to define the operation of the optical element,
The fθ lens 190 and the photosensitive drum 2 are arranged in a plane perpendicular to the optical axis.
The scanning direction of the light flux on 10 (FIG. 2) is defined as the main scanning direction, and the direction orthogonal to the main scanning direction in the plane perpendicular to the optical axis is defined as the sub scanning direction. Further, in the figure, an X axis parallel to the optical axis of the fθ lens 190, and a Y axis and a Z axis orthogonal to each other in a plane perpendicular to the X axis are defined. The Y axis and the Z axis correspond to the main scanning direction and the sub scanning direction, respectively.

Next, each component of the optical system will be described with reference to FIG. 3 showing the outline of the optical system of the above-mentioned apparatus. The light source unit 100 includes eight semiconductor lasers 101, eight optical fibers 120 that transmit divergent light beams emitted from these semiconductor lasers, and a fiber alignment block 1 that aligns these optical fibers 120 in a straight line.
30. The optical fiber 120 is a silica glass fiber having a core diameter of 6 μm and an overall diameter including the cladding of 125 μm.

The end of the optical fiber 120 including the incident end face 120a is held by a fiber support 319 which is a support tube. The fiber support 319 has an entrance end 1
The semiconductor laser 101 is held by the laser block 310 while the semiconductor laser 101 and the semiconductor laser 101 face each other. Then, the light flux emitted from the semiconductor laser 101 is reflected by the optical fiber 120.
Is incident on the incident end face 120a.

As shown in FIG. 3, in the optical path between the light source section 100 and the polygon mirror 180, a collimating lens 140 and a collimating lens 140 for making a divergent light beam emitted from the exit end face of the optical fiber into a parallel light beam are emitted. A slit 142 for controlling the beam shape by a rectangular opening having sides in the main scanning direction and the sub-scanning direction of the light beam, a half mirror 144 for separating the light beam transmitted through the slit 142 into two, and a light beam reflected by the half mirror 144. Dynamic prism 160 that sequentially controls by rotating the angle in the sub-scanning direction of
A cylindrical lens 170 for converging the light beam whose angle is controlled by 60 in the sub-scanning direction is provided.

The light flux transmitted through the half mirror 144 is incident on an APC (Automatic Power Control) signal detecting section 150 which detects a light amount and obtains a signal for controlling the output of the semiconductor laser. The APC signal detection unit 150 converges the light flux that has passed through the half mirror 144 by the condenser lens 151 and makes it enter the polarization beam splitter 153. Polarizing beam splitter 1
Reference numeral 53 separates the incident light flux into transmitted light that transmits in the incident direction and polarized light that is polarized in a direction orthogonal to the incident direction. The transmitted light is detected by the APC first light receiving element 155, and the polarized light is detected by the APC second light receiving element 157.

The exit end face 120b of the fiber 120 is
A fiber alignment block 130 and a fiber alignment block holder 300 (not shown) described later.
Thus, as shown in FIG. 4, they are arranged at a predetermined interval on a straight line inclined by a predetermined angle with respect to the main scanning direction to form a point light source array. The light flux from the point light source array including the eight point light sources passes through the collimator lens 140, the cylindrical lens 170, and the like in FIG.
An image is formed in the sub-scanning direction near the 0 mirror surface. The incident light flux on the polygon mirror 180 is scanned in the Y direction by the rotation of the polygon mirror 180 and is incident on the fθ lens 190.

The fθ lens 190 is a polygon mirror 18
From the 0 side to the folding mirror 200 side, negative, positive, and positive in the main scanning direction and the sub scanning direction, respectively.
The first, second, third, and fourth lenses 191, 193, 195, and 197 having positive and negative powers are used.
The light flux transmitted through the fθ lens 190 is reflected by the folding mirror 20.
0, the image is formed on the surface of the photoconductor drum 210 (FIG. 2), and the scanning speed in the main scanning direction becomes constant. In this way, the light beams from the eight point light sources form the row of beam spots shown in FIG. 5 on the image plane. The photoconductor drum 210 is rotationally driven in the arrow R direction in synchronization with scanning,
As a result, an electrostatic latent image is formed on the surface of the photoconductor drum 210.

Next, an embodiment of the scanning optical device of the present invention will be described. As shown in FIG. 2, a drawing opening 11 is provided on the bottom surface of the casing 1, and an adjustment opening 12 is provided on the side surface thereof. The drawing opening 11 is for guiding the light emitted from the fθ lens 190 which is an imaging lens and reflected by the folding mirror 200 to the surface of the photosensitive drum 210 which is an imaging surface. for that reason,
The drawing opening 11 is a rectangle having sides longer than the scanning range in the main scanning direction and the sub scanning direction so that the light emitted from the fθ lens 190 can pass through. Further, the mirror 200 is removable from the casing 1.

Like the drawing opening 11, the adjustment opening 12 is also a rectangle having sides longer than the scanning range in the main scanning direction and the sub scanning direction. In addition, the adjustment opening 12
Is the fθ lens 190 with the mirror 200 removed.
It is located in the optical axis direction of the fθ lens 190 so that the light emitted from the can be transmitted. Further, the adjustment opening 12 has a lid 13 for preventing dust from entering the casing 1.
Is provided. The lid 13 is screwed to the casing 1 so as not to come off easily.

FIG. 6 shows the scanning optical device during adjustment. At the time of adjustment, the scanning optical device is attached to the base frame 410. The base frame 410 is provided with legs 411 for supporting the casing 1 of the scanning optical device, and thereby the scanning optical device is supported horizontally. Adjustment opening 1
2 has sides longer than the scanning range in the main scanning direction and the sub-scanning direction, and by removing the mirror 20 and the lid 13, fθ
The transmitted light from the lens 190 is guided to the outside of the casing 1. That is, the transmitted light from the fθ lens 190 passes through the adjustment opening 12 and is in substantially the same plane as that of the scanning optical device 1, in other words, between the lower surface of the casing 1 and the surface of the upper lid 2 extended. Be guided.

The base frame 410 is provided with a measuring device 400 for measuring the beam diameter in the optical axis direction of the light emitted from the adjusting aperture 12 of the scanning optical device. Measuring instrument 4
00 has a light receiving surface at its tip, and measures the beam diameter within the light receiving surface.

The measuring device 400 is held by a base frame 410, and a unit frame 420, which is a plate member fixed to the base frame 410, extends in the main scanning direction (Y direction: a direction orthogonal to the paper surface in FIG. 6). A pair of guide rails 422 extending in the vertical direction are provided. A nut 423 is movably engaged on each of the guide rails 422, and a table 425 is fixed to the nut 423. A guide rail 426 extending in the optical axis direction (X direction) is formed on the table 425.
A nut 427 is movably engaged with the. And
A holding plate 430 holding the measuring device 400 is fixed to the nut 427. In this way, the measuring device 40
0 is movable in the main scanning direction (Y direction) and the optical axis direction (X direction).

Next, an outline of fine adjustment of the optical system using the adjustment opening 12 will be described with reference to FIG. 7 showing an image plane. At the time of manufacturing the scanning optical device, the scanning optical device is assembled as a single unit, and then the tilt or the curvature of the lens in the scanning optical device is finely adjusted while measuring the tilt or the curvature of the image plane. At this time, the polygon 180 (FIG. 6) is stopped and a single beam is emitted as emitted light. The single beam passes through the aperture 12 and forms a stationary beam spot on the image plane F as shown in FIG.

The beam diameter is measured by the measuring device 400 at several points in the optical axis X direction, and the position where the beam diameter becomes the minimum is the beam waist position, that is, the image forming position. Such measurement of the image forming position is also performed at several points in the main scanning direction (the central portion A and both ends B and C in the main scanning direction in FIG. 7). Then, the inclination or the curvature of the image forming surface is calculated from the data of the image forming positions defined at several points in the main scanning direction.

That is, for example, in FIG. 7, when the image forming position which should originally be the point B is the point B ′ and the image forming position which should originally be the point C is the point C ′, the image plane F is It can be seen that it is tilted (or rotated) in the D direction in the figure.
In such a case, the fθ lens 190 is moved until the image forming positions at the points B ′ and C ′ move to the points B and C ′, respectively.
Make fine adjustments such as adjusting the inclination of the appropriate lens inside.

As described above, according to the scanning optical system of the present embodiment, the positioning for moving the measuring device 400 in the optical axis X direction and the main scanning direction Y with high accuracy is substantially in the same plane as the scanning optical device. Can be done at. Therefore, the adjustment work becomes extremely easy as compared with the conventional one in which the measurement device is adjusted three-dimensionally under the scanning optical device 1.

[0028]

As described above, according to the scanning optical system of the first aspect of the present invention, the emission light is approximately in the same plane as the scanning optical device due to the adjustment aperture provided separately from the drawing aperture. Since the scanning optical system is guided to between the surfaces that extend the pair of surfaces that are arranged between them, the positioning of the measuring device can be performed in substantially the same plane as the scanning optical device, and the adjustment work is extremely difficult. It will be easier.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a scanning optical device according to the present invention.

FIG. 2 is a side view of the scanning optical device of FIG.

3 is a diagram showing an optical system of the scanning optical device of FIG.

FIG. 4 is a diagram showing a point light source array.

FIG. 5 is a diagram showing a beam spot.

FIG. 6 is a side view showing the scanning optical device during adjustment.

FIG. 7 is a perspective view showing an image plane.

[Explanation of symbols]

 1 Casing (Case) 2 Lid 11 Drawing Opening (One Opening) 12 Adjustment Opening (Other Opening) 13 Lid 100 Light Source 120 Fiber 140 Collimating Lens 180 Polygon Mirror 190 fθ Lens 200 Folding Mirror 210 Photoreceptor Drum 400 Measuring instrument 410 Base frame

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsunori Iima 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd.

Claims (5)

[Claims] 1. A scanning optical device comprising: a scanning optical system; and a case in which the scanning optical system is arranged between a pair of surfaces, wherein the case is provided with light emitted from the scanning optical system. Two openings for guiding to the outside are provided, and one of the two openings is for drawing, and the other opening is for guiding the emitted light between the surfaces respectively extending the pair of surfaces, A scanning optical device. 2. The scanning optical device according to claim 1, wherein the one opening guides the emitted light to the outside of a surface extending from each of the pair of surfaces. 3. The scanning optical device according to claim 1, wherein the other opening is for adjustment. 4. The emitted light passes through the one opening by attaching a mirror between the other opening and the scanning optical system, and passes through the other opening by removing the mirror. The scanning optical device according to claim 1, wherein: 5. The one opening according to claim 1, wherein the one opening is provided in one of the pair of surfaces.
The scanning optical device according to any one of 1.