JP2001033723A - Optical scanner and electrophotographic device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner made compact and capable of securing the positional accuracy of an optical system lens. SOLUTION: An image-formation optical system of an optical unit 5 being the optical scanner is constituted of a 1st lens 114 through which a light beam 105 deflected to perform scanning passes, a mirror 119 folding an optical path of the light beam 105 passing therethrough, and a 2nd lens 115 arranged at an upper part of the lens 114 so that it may be superposed on at least one part of the lens 114 and forming the folded light beam 105 into an image as a spot on a surface to be scanned 201.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used for an optical printer or the like for recording an image using a light beam such as a laser beam.

[0002]

2. Description of the Related Art An optical scanning apparatus that performs image recording by scanning and exposing a scanned surface serving as an image forming surface with a light beam such as a laser beam modulated by an image signal is widely applied to so-called optical printers and the like. . This optical scanning device uses a deflecting unit such as a rotary polygon mirror or a galvano mirror that reflects and deflects the light beam for scanning the light beam. The scanned light beam forms an image on the surface to be scanned by an f · θ lens or the like.

In such an optical scanning device, about 300 mm is required in some cases from the deflection point to the image formation point.
Therefore, the projection area of the optical scanning device requires a large area.
Conventionally, in order to reduce the size of the optical scanning device, a method has been adopted in which a folding mirror is inserted between scans, the optical path is folded, and the size is reduced.

On the other hand, the arrangement of the above-mentioned optical system lenses needs to be three-dimensionally arranged with a positional accuracy of 0.1 mm or less. In addition, the optical system lens is often composed of a plurality of lenses such as two or more lenses in order to contain optical aberration.

In order to make the optical scanning device compact, a method of turning the optical path halfway has been adopted.
Japanese Patent Application Laid-Open No. 2-190815 describes a method in which a light beam is folded before passing through an optical lens, and a method in which a light beam is folded after passing through an optical lens. There is also a method of folding back between both lenses.

In order to ensure the positional accuracy of each optical system lens, a method is adopted in which the vertical and horizontal height directions of the optical system lens are regulated to the housing by a leaf spring, adhesive, or the like.

[0007]

However, in the method described in Japanese Patent Application Laid-Open No. 2-190815, a folding mirror is provided in the middle of the optical path of the light beam, and the components of the optical scanning device are stacked and arranged. However, there is no description of a specific method of arranging the optical system lens requiring the highest positional accuracy among the elements, a means of ensuring the positional accuracy, and the like.

Particularly, in an optical scanning device having two or more lenses configured as an optical scanning system lens, it is important to secure the lens position accuracy.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical scanning device which can be made compact and can ensure the positional accuracy of an optical system lens, and an electrophotographic apparatus having the same.

[0010]

Means for Solving the Problems In order to achieve the above object, the features of the optical scanning device according to the present invention are as follows.
A first lens for passing an optical beam deflected and scanned by the imaging optical system of the optical scanning device, a mirror for turning an optical path of the passed light beam, and a first lens for overlapping at least a part of the first lens. And a second lens disposed on the top and imaging the folded light beam as a spot on the surface to be scanned.

Specifically, the present invention provides the following devices.

According to the present invention, there is provided a light source for generating a light beam, a converging optical system for converging the generated light beam, a deflecting means for deflecting and scanning the converged light beam, and a light source for deflecting and scanning the deflected light beam. An optical scanning device including an imaging optical system that forms an image as a spot on a surface to be scanned, wherein the imaging optical system is configured to pass the deflection-scanned light beam.
A lens, a mirror that folds an optical path of the passed light beam, and a light spot that is disposed on the first lens so as to overlap at least a part of the first lens and that is turned on as a spot on the surface to be scanned. An optical scanning device, comprising: a second lens that forms an image.

Further, the present invention provides a light source for generating a light beam, a converging optical system for converging the generated light beam, a deflecting means for deflecting and scanning the converged light beam, and the deflecting and scanning light. In an optical scanning apparatus including an imaging optical system that forms an image of a beam as a spot on a surface to be scanned, and a housing to which the light source, the deflecting unit, and the imaging optical system are attached, the imaging optical system includes: A first lens that passes the light beam that has been deflected and scanned, a mirror that folds an optical path of the light beam that has passed through, and a light spot that is disposed above the first lens and that is turned back on the surface to be scanned. The first lens and the second lens are attached to the housing, and each is positioned by a positioning member provided between the first lens and the second lens. Providing an optical scanning apparatus characterized by being regulated.

[0014] Preferably, the positioning member is provided with a shielding portion for shielding a light beam passing through other than the optical path.

Preferably, a dust-proof glass is provided on a window of the housing through which a light beam emitted to the outside of the housing passes, and an openable / closable cover is provided on the outside of the window.

The present invention also provides a photoreceptor, an optical scanning device for irradiating the photoreceptor with a light beam from below to form an image on the surface of the photoreceptor, and a developing device for developing the formed image. A light source that generates the light beam, a converging optical system that converges the generated light beam, and a deflecting unit that deflects and scans the converged light beam. An imaging optical system that forms an image of the deflected and scanned light beam as a spot on a surface to be scanned, the imaging optical system includes a first lens that passes the deflected and scanned light beam, A mirror that folds an optical path of the passed light beam, and a second lens that passes the folded light beam and forms an image as a spot on the surface to be scanned, wherein the second lens is a lens of the first lens. at least Is disposed over the first lens so as to overlap with parts, the mirror provides an electrophotographic apparatus characterized in that it is arranged substantially half the focal length.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical scanning device according to an embodiment of the present invention and an electrophotographic apparatus using the same will be described with reference to the drawings.

FIG. 1 shows a laser printer using an optical scanning device according to an embodiment of the present invention. The laser printer main body 25 includes developing units 1 to 4, an optical unit 5 as an optical scanning device, a charging unit 8, a photosensitive belt 22,
Transfer drum 21, registration roller 12, transfer roller 1
3, the static eliminator 15, the fixing device 19, the paper discharge roller 18, and the paper feed cassette 6 are main components.

FIG. 2 is a plan view of the optical scanning device of FIG. 1 with the upper cover removed, and FIG. 3 is a sectional view of the optical scanning device of FIG.

The optical unit 5 is made into a unit by using a housing 101 as a housing and mounting components inside and outside thereof. A rotary polygon mirror 104 driven to rotate by a scanner motor 103 fixed in a housing with a fixing screw 102 repeatedly scans the incident laser beam 105 in a direction parallel to the paper surface.

The laser beam 105 is applied to the housing 10
The light emitted from the laser diode 108 attached to the control circuit board 107 fixed to the outside of the side wall of the optical disk 1 with the fixing screw 106 is transmitted to the collimator 109 and the incident cylindrical lens 1.
10 converges so as to form a linear image on the deflecting and reflecting surface of the rotary polygon mirror 104 in the main scanning direction and in the sub-scanning direction.

That is, the light emitted from the laser diode 108 is transmitted from the side wall of the housing 101 to the housing 10.
1 and collimated by a collimator lens (not shown) of a collimator 109 supported by a base fixed to the control circuit board 107, and the incident cylindrical lens 1
At 10, the light converges on the deflection reflecting surface in the sub-scanning direction.

The laser beam 105 deflected and scanned by the rotary polygon mirror 104 passes through the first lens 114, turns the optical path back by the mirror 119, passes through the second lens 115, and is scanned on the surface of the photosensitive belt 22. An image is formed as a spot on 201. The scanning surface 201 is scanned and exposed while moving at a constant speed according to the rotation of the rotary polygon mirror 104.

First lens 114 and second lens 115
Are holding springs 116, 117 and fixing screws 120,
It is fixed to the housing 101 by 121.

As shown in FIG. 3, a window 210 is formed on the side wall of the housing 101 for emitting a deflected laser beam 105 and irradiating the scanned surface 201 of the photosensitive belt 22 with dust. It is closed with dustproof glass 118 for light shielding.

In the deflection range of the laser beam 105 deflected by the deflection reflecting surface of the rotary polygon mirror 104 and deflected by the scanning surface, the laser beam deflection position denoted by reference numeral 105a and the reference numeral
The photosensitive belt 2 is located between the laser beam deflection positions 5b.
An image forming range on the two surfaces to be scanned 201;
The laser beam deflection position denoted by reference numeral 105c is a reference position set in front of the image forming range.

The laser beam 105c is bent in the main scanning direction by a mirror 122 provided on a support stand 121 which is fixed to the housing 101 and fixed to the housing 101 with fixing screws, and is incident on a control circuit board 124 on which a light detecting element is mounted. The gap between the control circuit board 124 and the housing 101 is surrounded by a sealing material 125 made of urethane foam so as to maintain the dustproof property. It is fixed with screws 120.

FIG. 4 is a diagram showing the arrangement of the imaging optical system, and is an example in which a first lens 1140 and a second lens 1050 are arranged in series. However, the distance between the lenses differs depending on the lens specifications, but the arrangement range is large.

FIGS. 5 and 6 show a mirror 1 in the optical path.
In this example, the optical path is bent and the light path 190 is disposed, and this is a comparative example with the embodiment of the present invention. A first lens 1140,
Since the second lens 1050 and the mirror 1190 are separately fixed to the housing, they are arranged so as not to overlap each other. The arrangement range is smaller than in FIG.

FIG. 7 shows an example in which the optical path of the embodiment of the present invention is bent. The second lens 115 is disposed above the first lens 114 so as to be superimposed, and the mirror 1 is turned back.
19 is disposed at a position substantially half the focal length. By arranging in this manner, the range in which the component parts can be accommodated with respect to the scanned surface 201 is set to about 3
It can be made about / 4 compact.

Further, by using one mirror for turning back the optical path, the power attenuation due to reflection is reduced, the positional accuracy of the optical path is easily ensured, and the cost is reduced. There is.

As described above, in the present embodiment, when the second lens 115 is disposed above the first lens 114, the positioning of the second lens 115 is important. The first lens 114 and the second lens 115 need to have mounting accuracy in the x, y, and z directions in FIGS. 2 and 3, respectively.

When the first lens 1140 and the second lens 1150 are arranged as shown in FIG.
By providing positioning on the housing,
The position accuracy in the x, y, and z directions can be maintained and fixed. The second lens 1150 needs to ensure the positional accuracy of the first lens 1140 in the y direction, that is, the distance between the two lenses, the z direction, that is, the center in the height direction, and the x direction, that is, the center in the longitudinal direction of the lens. .

The second lens 1150 is connected to the first lens 114
0, the length in the x direction is longer than that of the first lens 1140. By positioning and fixing the position outside the first lens 1140, the positional accuracy in the z direction and the y direction can be ensured.

However, in the x direction, that is, the second lens 1150
When the center of the first lens 1140 and the second lens 1150 in the x direction is aligned with each other in a longitudinal positional relationship between the first lens 1140 and the first lens 1140, the first lens 1140 is disposed above the second lens 1150. In such a case, it is impossible to form the positioning of the longitudinal center of the second lens 1150 in the housing so as not to disturb the scanning of the laser beam 105 by a general molding technique.

In the embodiment of the present invention, as shown in FIG. 3, positioning members 130 and 131 are provided at the center of the first lens 114 in the longitudinal direction. First lens 114
The positioning accuracy in the longitudinal direction is secured by the positioning 130 and the groove 132 provided on the housing 101 at the position where the first lens 114 is disposed.

The positional accuracy of the first lens 114 in the y direction, that is, the short direction, and the z direction, that is, the vertical direction, is fixed by being pressed against the arranging parts 151 and 152 provided on the housing 101 by the pressing spring 116.

The second lens 115 is provided with a positioning 133 at the center in the longitudinal direction. A positioning member 140 is provided for positioning the second lens 115. The positioning member 140 includes a lens positioning 13.
Grooves 135 corresponding to the first and second lenses 132 are provided, and are arranged above the first lens 114.

The grooves 135 having the same positioning 131, 133
Therefore, it can be said that the positional accuracy of the first lens 114 and the second lens 115 in the longitudinal direction is good.

Further, the positioning portion 13 is provided by the lens structure.
When there is a distance of 1 and 133, the groove 1
If the lens 35 is not arranged in the longitudinal direction perpendicular to the first lens 114, the positional accuracy of the second lens 115 in the longitudinal direction is deteriorated.

In this embodiment, the positioning member 140 is mounted on the guide surface 14 so that the first lens 114 and the second lens 115 are arranged parallel to each other in the longitudinal direction and the vertical direction.
1, 142 are provided. Further, guides 155 and 156 are provided on the housing 101 and the positioning member 40 is provided.
Are arranged perpendicular to the length of the first lens 114.

The second lens 115 is disposed downstream of the first lens 114 in the optical path, and has a longitudinal length of the first lens 114.
It is longer than the lens 114. With respect to the short direction and the vertical direction of the second lens 115, the holding spring 117 is provided on the arrangement portions 157 and 158 provided outside the first lens 115.
Press to fix.

With such a structure, the accuracy of the center position in the longitudinal direction of the second lens 115 with respect to the first lens 114 is almost directly aligned with the positioning member 140, but the accuracy can be easily secured. .

FIG. 8 shows that the positioning member 40 is connected to the first lens 1.
14 shows a view from the 14 side, that is, from the back side. on the other hand,
By integrally forming or fixing the holding spring 116 for fixing the first lens 114 to the positioning member 140,
Means for fixing the holding spring 116 to the housing 101;
Generally, fixing screws can be omitted. The holding spring 116 is
It is temporarily fixed to a rib 143 provided on the positioning member 140 and is integrally fixed to the housing 101 with a screw. The rib 143 also functions as a stopper for the spring 116.

After the assembling, the holding spring 116 and the first lens 114, which are the components disposed below the positioning member 140, are difficult to confirm the presence / absence of each component and the mounting condition. For this reason, the positioning member 140 includes the first lens 1
Holes 144 and 145 are provided so that a contact portion between the holding spring 14 and the holding spring 116 can be seen.

One of the problems of the optical scanning device is a ghost. This is because the light beam that has hit the scanning surface, the lens that is the scanning optical system, and in some cases, the pressing spring of the lens and the mirror is reflected, enters the rotary polygon mirror 104, reflects, scans again, and scans the scanning surface 201. As a result, as a result, the electrophotographic apparatus may draw an image on the portion.

As a countermeasure, a shielding plate for preventing portions other than the original optical path is provided on the entrance side or the exit side of the lens serving as the scanning optical system so that light cannot pass therethrough. Generally, a plastic molded product is used as the housing of the optical scanning device. However, it is difficult to make the housing above the optical path into the housing due to the structure of the molding die.

Therefore, it is necessary to form the shielding plate as a separate component. The positioning member 140 is a rotating polygon mirror 104.
The ribs 146 and 147 are provided on the positioning member 140 and located above the first lens 114 close to the first lens 114, thereby functioning as a shielding plate above the optical path. This allows
A good image can be obtained without configuring the shielding plate as a separate component and without the need for fixing means.

As described above, by combining the functions into one component, the effect in terms of cost reduction can be obtained.

On the other hand, in the laser printer body 25,
When a laser beam is incident on the photosensitive belt 22 from below, the dust such as toner scattered in the apparatus is applied to the optical unit 5 as an optical scanning apparatus by the unit cover 1 at the upper opening.
90. If the deposit blocks the optical path, image defects such as image omission will occur.

For this reason, normally, a shutter is provided to protect the dust-proof glass 118 from which the light beam of the optical scanning device is emitted, an air flow path is narrowed, and an expansion chamber is provided immediately after that, or some of them are provided. By providing the continuous structure, the entrance of dust is reduced by the labyrinth effect.

9 and 10 are cross-sectional views of the vicinity of the dust-proof glass and the expansion chamber. The cover member 200 disposed above the unit cover 190 includes expansion chambers 211 and 212, an opening window 214 to the outside, and a shaft 213. The cover member 200 is configured to rotate around a shaft 213.

As shown in FIG. 9, at the first fixed point, the laser beam 105 passes through the opening window 214, and
1 is imaged. On the other hand, dust and the like from the outside enter through the opening window 214 and diffuse in the expansion chambers 212 and 211, so that the dust-proof glass 1
18 to reduce the amount of dust deposited on it.

Further, as shown in FIG.
00 rotates in the direction of the arrow around the shaft 213 to the second fixed point. At this time, the upper part of the dustproof glass 118 is exposed, and the dust adhered on the dustproof glass 118 can be removed.

As described above, the cleaning operation for cleaning the dust-proof glass of the optical scanning device can be facilitated, and the maintainability can be improved.

At the second fixed point, the laser beam 1
05 corresponds to the cover member 200 and does not reach the scanned surface 201. By detecting that the cover member 200 has not arrived, it also serves as a check mechanism for forgetting to return the cover member 200 to the first fixed point after maintenance.

[0057]

According to the present invention, since the optical scanning device can be made compact, the space around the optical scanning device can be used effectively, and the size of the electrophotographic apparatus can be reduced efficiently. In addition, since the positional accuracy of the optical system lens can be ensured, the quality of the scanning exposure can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser printer using an optical scanning device according to an embodiment of the present invention.

FIG. 2 is a plan view of an optical unit that is the optical scanning device of FIG. 1 with an upper cover removed.

FIG. 3 is a sectional view of the optical unit of FIG. 2;

FIG. 4 is a layout diagram of an imaging optical system.

FIG. 5 is an arrangement diagram in which an optical path of an imaging optical system is bent, and is a comparative example with the embodiment of the present invention.

FIG. 6 is a layout diagram in which an optical path of an imaging optical system is bent, and is a comparative example with the embodiment of the present invention.

FIG. 7 is a diagram illustrating an example in which an optical path according to an embodiment of the present invention is bent.

FIG. 8 is a plan view of a positioning member of the optical system lens of FIG. 2;

9 is a cross-sectional view of the vicinity of a dustproof glass and an expansion chamber provided on an upper cover of the optical unit in FIG. 1;

FIG. 10 is a cross-sectional view when the cover member of FIG. 9 is opened.

[Explanation of symbols]

1, 2, 3, 4 developing unit, 5 optical unit, 22 photosensitive belt, 25 laser printer body, 101 housing, 104 rotating polygon mirror, 105, 105a, 105
b, 105c: laser beam, 114: first lens, 1
15: second lens, 118: dustproof glass, 119: mirror, 201: scanned surface, 140: positioning member, 14
6,147 ... rib, 190 ... unit cover, 200 ...
Cover member, 210, 211 ... expansion chamber, 212 ... opening window, 213 ... shaft

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2C362 BA86 BA87 BA90 DA02 DA03 DA06 DA14 DA27 2H045 AA01 CA63 DA02 DA04 5C072 AA03 BA01 BA04 DA02 DA04 DA15 DA21 HA02 HA13 XA05

Claims (5)

[Claims] A light source for generating a light beam; a converging optical system for converging the generated light beam; a deflecting means for deflecting and scanning the converged light beam; An optical scanning device having an image forming optical system that forms an image as a spot on a surface, wherein the image forming optical system includes a first lens that passes the deflection-scanned light beam, and an optical path of the passed light beam. And a second lens disposed on the first lens so as to overlap at least a part of the first lens and configured to form an image of the folded light beam as a spot on the surface to be scanned. An optical scanning device. A light source for generating a light beam; a converging optical system for converging the generated light beam; a deflecting means for deflecting and scanning the converged light beam; An optical scanning device comprising: an imaging optical system that forms an image as a spot on a surface; and a housing to which the light source, the deflecting unit, and the imaging optical system are attached. A first lens that passes the light beam that has passed through, a mirror that folds the optical path of the light beam that has passed therethrough, and a mirror that is disposed above the first lens and forms an image of the folded light beam as a spot on the surface to be scanned. The first lens and the second lens are attached to the housing, and their positions are respectively regulated by positioning members provided between the first lens and the second lens. An optical scanning device characterized by the above-mentioned. 3. The method according to claim 2, wherein:
An optical scanning device comprising: a shielding unit that shields a light beam that passes through a path other than the optical path. 4. A housing according to claim 2, wherein a dust-proof glass is provided on a window of said housing through which a light beam emitted out of said housing passes, and an openable / closable cover is provided outside said window. Optical scanning device. 5. A photoreceptor, an optical scanning device for irradiating the photoreceptor with a light beam from below to form an image on the surface of the photoreceptor, and a developing device for developing the formed image. In the electrophotographic apparatus, the optical scanning device includes: a light source that generates the light beam; a converging optical system that converges the generated light beam; a deflecting unit that deflects and scans the converged light beam; An imaging optical system that forms an image of the obtained light beam as a spot on a surface to be scanned, wherein the imaging optical system includes a first lens that passes the light beam that has been deflected and scanned; A mirror that folds an optical path of the beam, and a second lens that passes the folded light beam and forms an image on the surface to be scanned as a spot, wherein the second lens is at least part of the first lens. To overlap The electrophotographic apparatus according to claim 1, wherein the mirror is disposed above the first lens, and the mirror is disposed at a position substantially half a focal length.