JPS6218532A - Scan optical system - Google Patents

Abstract

PURPOSE:To shorten a distance between an object surface and a photosensitive body surface and to compact a device by providing a toric roof mirror lens whose adjacent surfaces are light-shielded. CONSTITUTION:A toric roof mirror lens 2 has a cylindrical face 4 being the specific mode of a toric face having refraction force only in a direction A and a roof mirror face 6 extending in a direction B. Plural toric roof mirror lens 2 are arrayed in the direction A so as to be adjacent, and form a lens array 10. Here the adjacent faces of each toric roof mirror lens 2 are light- shielded and are taken for light shielding faces.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning optical system for 1-magnification imaging used in facsimile machines, copying machines, intelligent printers, and the like.

-The light is 1. In the scanning optical systems of copiers, facsimile machines, intelligent printers, etc., those that use ordinary optical lenses have high resolution, a deep depth of focus, and functions such as variable magnification. Although this is possible, it has the disadvantage that the lens is expensive and its conjugate length is long, making it large. Therefore, various proposals have been made to replace the lens system with a compact and inexpensive lens array.

For example, when small lenses are arranged in a row and used as a lens array, if an inverted real image of the object is formed on the photoreceptor surface, the entire image will be different from the object, which is inconvenient. Therefore, another small lens is used to create an erect real image on the photoreceptor surface using the inverted real image as the object surface. By these means, the image of the object is formed on the photosensitive surface as a real, life-sized royal image.

However, in reality, due to problems with aberration performance, it is not possible to obtain satisfactory results by forming an inverted real image using only one small lens, and it is necessary to use a plurality of small lenses. The same can be said of small lenses that convert an inverted real image into an erect real image. Moreover, it is a single lens array (in this case, since the Royal Real Image is dark, multiple rows of lens arrays would be stacked, making the configuration extremely complicated and expensive.In addition, such a lens system Therefore, it is difficult to extremely shorten the conjugate length between the object surface and the photoreceptor surface.

Also known is a convergent light transmitting array in which lenses each having a refractive index distribution formed by ion exchange are arranged in an array in the radial direction of a glass rod to form an erect image at a same magnification. This has the advantage of shortening the conjugate length between the object plane and the photosensitive surface, but has the disadvantages of large light loss, shallow depth of focus, and high cost.

Furthermore, after W of each lens of the lens array,
A roof mirror array in which roof mirrors are arranged is also known. However, this roof mirror array has the disadvantage that the surface precision of one roof surface relative to the lens array greatly affects the imaging performance of that roof mirror, so if the precision of the roof surface is slightly poor, the imaging performance will quickly deteriorate. be. Also,
Since the precision of each roof surface affects the overall imaging performance, uneven imaging may occur. Although the above-mentioned drawbacks can be eliminated if the roof surface is manufactured with high precision,
In that case, the roof mirror array itself becomes expensive.

The present invention has been made in view of the above-mentioned drawbacks of the conventional art, and its purpose is to shorten the distance between the object surface and the photoreceptor surface to make the device compact, and also to simplify the structure and reduce manufacturing costs. Another object of the present invention is to provide a scanning optical system with low loss of light quantity.

One Step to Solve the Problems In order to achieve the above object, the scanning optical system according to the present invention includes a roof mirror and a toric surface having refractive power at least in the main scanning direction between the object plane and the image plane. and a toric roof mirror lens array in which a large number of toric roof mirror lenses each having a roof mirror surface having a roof surface in the main scanning direction are arranged in an array, and adjacent surfaces between the respective toric roof mirror lenses are shielded from light. shall be.

1-Dish In the present invention, a roof mirror is used to shorten the distance between the object surface and the photoreceptor surface while ensuring a sufficient optical conjugate length. The light beam emitted from the object is reflected by the object-side mirror surface of the roof mirror and enters the toric roof mirror lens array.
A large number of toric roof mirror lenses each having a toric surface having refractive power in the main scanning direction and a roof mirror surface having a roof surface in the main scanning direction are arranged in an array,
The adjacent surfaces between each toric roof mirror lens are continuously illuminated. Therefore, the light beam reflected from the object side of the roof mirror passes through the toric surface of this lens array,
It is reflected by the roof mirror surface. This light beam passes through at least one toric surface, is reflected again by the surface of the roof mirror on the photoreceptor side, and forms an image on the photoreceptor surface.

χ1X Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 3 is a perspective view showing a toric mirror lens constituting a toric roof mirror lens array of a scanning optical system according to a first embodiment of the present invention. In Figure 3, the toric surface/"i mirror lens (2) has a cylindrical surface (4), which is a special form of a toric surface that has refractive power only in the direction (A) in the figure, and a cylindrical surface (4) in the (B) direction in the figure. The toric roof mirror lens (2) has a mirror surface (6) extending in the direction (6).
A lens array (10) shown in FIG. 4 is formed by arranging a large number of lenses adjacent to each other in the direction A). Here, as shown in FIG. 3, the adjacent surface (8) of each toric roof mirror lens (2) is subjected to a light-shielding treatment to serve as a light-shielding surface. In FIGS. 3 and 4, the (A) direction indicates the main scanning direction, and the (B) direction indicates the sub-scanning direction orthogonal thereto. Furthermore, as shown in FIG. 3, the thickness of one toric roof mirror lens (2) in the (A) direction is D.
and its length is L.

Figure 4 shows such a toric roof mirror lens (2
) is combined with a cylindrical lens (12) having refractive power only in the sub-scanning direction (B). This toric roof mirror lens array (10) and cylindrical lens (12) constitute an imaging lens that forms an image of an object on a photoreceptor.

Here, as shown in FIG. 3, the surface (4) of the toric roof mirror lens (2) is not limited to a cylindrical surface having refractive power in only one direction ( , 155 As shown in the diagram, (A) direction and (
B) A toric surface having a different refractive power depending on the direction may be used. However, here, the cylindrical surface is included in the toric surface as one form of the toric surface. Furthermore, the present invention is not limited to the arrangement in which a single cylindrical lens (12) is arranged in front of the toric roof mirror lens array (10) as shown in FIG. A cylindrical lens having refractive power only in the sub-scanning direction is configured by a plurality of lenses (12a) (12b), and a toric roof mirror lens array (1
The cylindrical surface 0) may be configured in combination with another lens array (4a).

Figure 1 shows the Dori Tsukugutsu 1-mirror lens array (10) and cylindrical lens (12) shown in Figure 4 above.
FIG. 3 is a cross-sectional view in the sub-scanning direction of a scanning optical system using the following. In FIG. 1, (14) indicates a glass plate, and (16) indicates an original placed thereon.

(18) is a light source; (20) is a roof mirror having a reflective surface (M, ) on the object side and a reflective surface (M2) on the photoreceptor side;
(22) is a photoreceptor.

The light reflected from the original (16) illuminated by the light source (18) is reflected by the object-side reflective surface (M) of the roof mirror (20).
1) and enters the toric roof mirror lens array (10) via the cylindrical lens (12) having refractive power only in the sub-scanning direction (B). The cylindrical lens (12) converts the light beam into approximately 77 ocals in the sub-scanning direction, and the beam is incident on the toric roof mirror lens array (10). Since the cylindrical surface (4) of the toric roof mirror lens array (10) has no refractive power in the sub-scanning direction, the light beam incident on the toric roof mirror lens array (10) is not refracted in the sub-scanning direction by this surface and is directed to the roof mirror surface (6). Then, it is reflected by this roof mirror surface (6). Here, since the cylindrical surface (4) has refractive power in the main scanning direction, the light beam incident on the roof mirror surface (6) is approximately 77 ocular in the main scanning direction as well.

That is, the light beam incident on the roof mirror surface (6) is made almost afocal in the sub-scanning direction by the cylindrical lens (12), and made 77 ocal in the main scanning direction by the cylindrical surface (4).

Such a light beam is reflected by the roof mirror surface (6) of the toric roof mirror lens array (10), and is reflected by its cylindrical surface (4) and the cylindrical lens (
12), is reflected by the photoconductor side reflective surface (M2) of the roof mirror (20), and is reflected by the photoconductor (22).
, and a life-sized image of the original W4 (16) is formed on the photoreceptor (22). Here, regarding the sub-scanning direction (B),
An inverted, life-size image of the original (16) is formed on the photoreceptor (22).

On the other hand, FIG. 2 shows a cross-sectional view in the main scanning direction of this embodiment, and as is clear from the figure, in the main scanning direction,
An erect, life-size image of the original (16) is formed on the photoreceptor (22). In FIG. 2, the light beam in the shaded area reaches the photoreceptor (22) and contributes to image formation, while the other light beams are cut off by the light shielding surface (8).

Here, the image plane illuminance I (relative illuminance) on the photoreceptor (22) is the height from the optical axis on the original m (16), the so-called image height) Y
, as shown in the graph of FIG. And this maximum image height Y max is the cylindrical surface (
4) and the roof mirror surface (6). In other words, the larger the distance, the smaller the maximum image height Y max, and conversely, the smaller the distance, the smaller the maximum image height Y max.
Wax gets bigger.

If the maximum image height Yn+ax is set to be equal to the thickness 3D of one toric roof mirror lens (2), the image surface illuminance I obtained as a result of superimposing a large number of toric roof mirror lenses (2) is , becomes almost constant as shown by Is in FIG. 8, which shows the relative illuminance in the scanning direction on the image plane. Therefore, by setting in this way, an image without uneven illuminance can be obtained.

FIG. 9 is a cross-sectional view in the sub-scanning direction showing a scanning optical system according to a second embodiment of the present invention, and members that act in the same manner as in FIG. . In the second embodiment shown in FIG. 9, instead of the single cylindrical lens (12) in FIG. 1, a pair of cylindrical lenses (24) and (26) are arranged perpendicular to the optical axis. Object-side reflective surface (Ml) of roof mirror (20) and toric roof mirror lens array (10)
and between the photoreceptor side reflective surface (M2) and the toric roof mirror lens array (10).

With this configuration, aberration correction becomes easier, and the F number of the scanning optical system can be reduced to obtain a brighter image plane.

Further, FIG. f510 is a cross-sectional view in the sub-scanning direction showing a scanning optical system according to a third embodiment of the present invention. In this example,
The object side reflective surface of the original (16) and the roof mirror (20) (
Cylindrical surfaces r(28) and (30) are arranged between the photoreceptor side reflecting surface (M2) of the roof mirror (20) and the photoreceptor (22), respectively. With this configuration, compared to the first embodiment shown in FIG. By reducing the image height Y IIIax, it is possible to reduce flare components and obtain an image with good imaging performance.

FIG. 11 is a cross-sectional view in the sub-scanning direction showing a scanning optical system according to a fourth embodiment of the present invention. In this embodiment, in order to reduce the F number in the sub-scanning direction and increase the amount of light, in addition to the cylindrical lens (12) in front of the toric roof mirror lens array (10), an original (16) and a roof mirror are installed. (20) with the object side reflective surface (Ml),
and the photoreceptor side reflective surface (M2) of the roof mirror (20)
Cylindrical lenses (32) and (34) are arranged between the roof mirror (20) and the photoreceptor (22), respectively, at substantially symmetrical positions with respect to the roof mirror (20). These cylindrical lenses (32) and (34) act as condenser lenses for converging light beams rather than correcting aberrations.

Furthermore, FIG. 12 is a sectional view in the sub-scanning direction showing a scanning optical system according to a fifth embodiment of the present invention. In this example,
Instead of using a cylindrical lens, the cylindrical surface (4
) is a surface (
36). With this configuration, there is no need to use a cylindrical lens, so the configuration can be made simpler.

In the above embodiment, the optical axis of the toric roof mirror lens array (10) does not need to be arranged perpendicular to the optical axis of the scanning optical system, and the optical axis of the toric roof mirror lens array (10) does not need to be arranged perpendicularly to the optical axis of the scanning optical system. 20), the optical axis position on the object surface side, and the optical axis position on the photoreceptor side may be arbitrarily set.

In the above embodiment, the cross sections of the cylindrical surface of the cylindrical lens and the cylindrical surface of the toric roof mirror lens array were each formed by a circle, but the present invention is not limited to this, and these cylindrical surfaces If the cross section of the surface is formed by an aspheric surface such as an ellipse or a parabola, various aberrations can be better corrected.

In these examples, the surface of the document illuminated by a light source such as a copying machine or facsimile was considered as the object surface, but the object surface may also be a self-emitting LED array or a hot cathode fluorescent tube array, or a liquid crystal or PLZT. An optical shutter array can also be used as an object surface. Furthermore, the imaging lens and condenser lens are not limited to glass, but may also be made of plastic.

Lesson I and Kujimi - As detailed above, the scanning optical system according to the present invention includes, in the distance between the object plane and the image plane, a roof mirror, a toric surface having refractive power at least in the main scanning direction, Toric shoes 1 in which a large number of toric roof mirror lenses each having a roof mirror surface having a roof surface in the main scanning direction are arranged in an array, and the adjacent surfaces between each toric roof mirror lens are shielded from light.
With this configuration, a royal real image can be obtained in the main scanning direction, and sufficient optical performance as a scanning optical system can be obtained. In the sub-scanning direction, since the amount of light on the image plane can be increased, the light flux can be efficiently collected on the image plane, and a bright image can be obtained. Furthermore, since a roof mirror is used, the distance between the object plane and the image plane can be shortened, making the apparatus compact.

Further, since the roof mirror surface of each lens in the toric roof mirror lens array is manufactured as a single lens, it can be manufactured with extremely high precision compared to a roof mirror array in which a plurality of roof mirrors are arranged side by side. Furthermore, according to the present invention, it is only necessary to stack a large number of toric roof mirror lenses and apply light shielding treatment to the adjacent surfaces of each lens.
There is no need to separately provide a light shielding plate to block light leaking from the imaging lens, making assembly and VLR& very easy.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view in the sub-scanning direction showing a scanning optical system according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view in the main-scanning direction, and FIG. 3 forms a toric roof mirror lens array. A perspective view of a toric roof mirror lens. Figure 4 is a perspective view showing an imaging lens including the toric roof mirror lens array. Figure 5 is a perspective view of a modification of the toric roof mirror lens. Figure 6 is a toric roof mirror lens. A perspective view showing a modified example of an imaging lens including a lens array, FIG. 7 is a graph showing the relationship between the image height and relative illuminance, and FIG. 8 is an image plane of one of the toric roof mirror lenses in the sub-scanning direction. A graph showing the illuminance distribution, FIG. 9 is a cross-sectional view in the sub-scanning direction showing a scanning optical system according to a second embodiment of the present invention, and FIG. 10 is a sub-sectional view showing a scanning optical system according to a third embodiment of the present invention. 11 is a sectional view in the sub-scanning direction showing the scanning optical system of the f54 embodiment of the present invention; FIG. 12 is a sectional view in the sub-scanning direction showing the scanning optical system of the fifth embodiment of the present invention. FIG. (2); ) - Rick Dacha mirror lens, (4): )
- Rick surface, (6); Roof mirror surface, (8); Light-shielding surface, (10);) - Rick roof mirror lens array, (A)
; Main scanning direction, (B); Sub-scanning direction, (16): Object plane, (22): Image plane, (20); Roof mirror. Applicant: Minolta Camera Co., Ltd. Figure 4 q Figure 5 Figure 9 Figure 1 θ Figure h

Claims (1)

[Claims] 1. A toric roof which has a roof mirror, a toric surface having refractive power at least in the main scanning direction, and a roof mirror surface having a roof surface in the main scanning direction, between the object plane and the image plane. A large number of mirror lenses are arranged in an array,
A scanning optical system comprising: a toric roof mirror lens array in which adjacent surfaces between the respective toric roof mirror lenses are shielded from light; 2. The scanning optical system according to claim 1, wherein the toric surface of the toric roof mirror lens has refractive power in each of the main and sub-scanning directions. 3. The scanning optical system according to claim 1, further comprising at least one toric lens having refractive power in at least the sub-scanning direction. 4. The scanning optical system according to claim 3, wherein the toric lens has a cylindrical surface in the sub-scanning direction. 5. The scanning optical system according to claim 4, wherein the toric surface of the toric roof mirror lens has a cylindrical surface in the main scanning direction. 6. The scanning optical system according to claim 4, characterized by having a lens array having a cylindrical surface in the main scanning direction. 7. The scanning optical system according to claim 5, wherein at least one of the cylindrical surfaces is an aspherical surface.