JPH0511363A - Illuminating device - Google Patents

Abstract

PURPOSE:To improve the efficiency of condensing light quantities by using two independent polarizing means which do not change convergency at all in one direction of two orthogonal directions and has a collimating function to another direction. CONSTITUTION:A reflection mirror 4 as the 1st polarizing means for collimating the divergent light emitted from a spot light source 1 in one direction and a cylindrical lens 3 as the 2nd polarizing means for collimating in a perpendicular direction are respectively independently disposed. The luminous flux emitted from the light source is first collimated only in one direction by the reflection mirror 4 which is the 1st polarizing means and is then admitted into the cylindrical lens 3. This cylindrical lens 3 acts as the 2nd polarizing means and collimates the light in the perpendicular direction. The perfect collimated beams of light, then, arrive at a condenser means and are condensed to an area to be illuminated. The collimation near the light source is possible in this way and the efficiency of condensing the light quantities is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device used in a copying machine or the like, and more particularly to an illuminating device for scanning an illuminated area by fixing a light source and moving a reflective optical system.

[0002]

2. Description of the Related Art Heretofore, as an illuminating device for scanning a region to be illuminated by moving only a reflection optical system with respect to a fixed light source, one disclosed in Japanese Patent Publication No. 53-41976 has been known. There is. For example, as shown in FIGS. 9 to 11, the light from the light source 100 is converted into a parallel light flux using a parabolic mirror 120 having the light source as a focal point or another collimating lens, and the parallel light flux is received. A parabolic reflector 110 having a focal point in the illumination area W is used to collect light, and the reflector 110 is a part of the reflective optical system.
The area to be illuminated is scanned by scanning.

[0003]

However, in such a prior art, as described above, the light flux from the light source 100 is
Only one parabolic mirror 120 and another collimating lens are used to collimate (collimate) the divergent light flux at once.

However, the parabolic mirror and the collimating lens for collimating are formed elongated as shown in FIG. Therefore, while the length of the collimated light flux in the longitudinal direction is 200 to 300 mm,
The width direction is only 30 to 40 mm, which is several times the slit width. Therefore, the distance between the light source and the apex of the curved surface is substantially determined by the longitudinal width of 200 to 300 mm, and the two cannot be brought close to each other. Therefore, there is a problem that the efficiency of collecting the amount of light is significantly deteriorated in the lateral direction.

Further, in the longitudinal direction, although a considerably large angle can be condensed, the light amount difference between the central portion and the peripheral portion in the longitudinal direction becomes too large. Therefore, in order to adjust the light quantity to the peripheral area, it is usually necessary to use a filter or a photoelectric correction plate to greatly reduce the light quantity in the central area, and there is also a problem that the light utilization efficiency is rather lowered. .

The present invention has been made in order to solve the above-mentioned problems of the prior art. The purpose of the present invention is to collimate a light beam from a fixed light source in only one direction by the first deflecting means, For the vertical direction, the second
2 which is orthogonal, such as collimating by the deflecting means
It is possible to perform collimation near the light source by using two independent deflecting means that do not change the convergence in one direction and collimate in the other direction. An object of the present invention is to provide a lighting device capable of increasing the efficiency of collecting the amount of light and capable of being downsized.

[0007]

In order to achieve the above object, in the present invention, a fixed point light source and a semi-cylindrical shape having the point light source as a focal point and having a collimating function in one direction are provided. A reflecting mirror, a cylindrical lens having a collimating function in another vertical direction that is not collimated with respect to a light beam emitted from the reflecting mirror, and a movement of the light beam emitted from the cylindrical lens to be condensed in an illuminated area. It is characterized in that it has a scanning type light collecting means.

The reflecting mirror is formed so that its half-cylindrical cross section is formed into a parabolic shape, or the semi-cylindrical cross section has one focus at a point light source position. Can be shaped so as to form a part of an ellipse.

If the cylindrical lens is formed as a cylindrical Fresnel lens, it can be made thin.

[0010]

Then, the luminous flux emitted from the light source is first collimated in only one direction by the reflecting mirror serving as the first deflecting means,
Enter the cylindrical lens. Next, when this cylindrical lens serves as the second deflecting means and performs collimation in the vertical direction, a perfect parallel light flux reaches the light converging means and is condensed in the illuminated area.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. FIG. 1 shows an illumination device according to a first embodiment of the present invention, in which 1 is a fixed point light source. In order to collimate the divergent light flux from the point light source 1 in the vertical direction, the reflecting mirror 2 is arranged with the point light source as the focal point.
The reflecting mirror 2 is a first deflecting means, and has a semi-cylindrical inner surface for reflecting light from the point light source 1, and its cross section (a cross section taken in the vertical direction in FIG. (See 3)
Is shaped like a parabola.

Next, as shown in FIG. 2, the reflected light flux from the reflecting mirror 2 is received, and another vertical direction (horizontal direction in FIG. 1) is received.
About 3 are arranged to collimate
And it is a cylindrical lens. This cylindrical lens 3 serves as a second deflecting means, and the light flux that has passed through this cylindrical lens 3 becomes a perfect parallel light flux. Then, by the reflecting mirror 4 as the condensing means of the moving scanning system,
As shown in FIG. 3, the light is focused on the illuminated area.

According to the apparatus of this embodiment having the above-mentioned structure, the divergent light emitted from the point light source 1 is collimated by the semi-cylindrical reflecting mirror 2 only in the lateral direction (vertical direction in FIG. 1) and in the longitudinal direction (FIG. 1). Since there is no light condensing power in the horizontal direction), as shown in FIG. 2 shown from above in FIG. 1, a linearly collimated line is formed at the position of the parabola quasi-line A drawn by the reflecting mirror 2. It becomes a diverging light flux as if there were a light source. Then, the cylindrical lens 3 collimates the luminous flux diverging in the longitudinal direction. After passing through the cylindrical lens 3, the light beam is collimated in all of the vertical and horizontal directions, so that it becomes a perfect parallel light beam.

If the focal length of the cylindrical lens 3 is set larger than the focal length of the reflecting mirror 2 in the lateral direction, the light quantity ratio between the central portion and the peripheral portion in the longitudinal direction will be smaller than in the conventional case. You can also do it.

Further, as is apparent from FIG. 3 which is a side view of FIG. 1, since the reflecting mirror 2 does not have a curvature in the longitudinal direction unlike the conventional apparatus, the reflecting mirror 2 does not have to be made large, and moreover, it does not have to be formed conventionally. Since the shape is easier to make, the distance between the light source 1 and the reflecting mirror 2 can be reduced, and the light collection efficiency can be increased in the lateral direction.

As described above, the luminous flux completely collimated by the reflecting mirror 2 and the cylindrical lens 3 is made into a slit shape in the illuminated area 6 by the reflecting mirror as a focusing means of the moving scanning system shown by 4 in the figure. Illuminate while scanning.

Reference numeral 5 in FIGS. 1 to 3 is a small reflecting mirror for returning a light beam which goes directly to the direction of the cylindrical lens 3 to the direction of the point light source 1 again. The reflecting mirror 5 further enhances the illumination efficiency, and also has a function of removing stray light traveling toward the cylindrical lens 3.

Further, FIG. 4 shows an improved example of the moving reflecting mirror 4 shown in FIG. That is, an example in which the reflecting mirror 4 is divided into two is shown, and by making it possible to illuminate the illuminated area from the left and right in this manner, for example, when illuminating a cut and pasted original or the like to make a copy, the step difference is visible. An illumination system that is hard to stand on can be obtained.

FIG. 5 shows an illumination device according to the second embodiment of the present invention. The cylindrical lens 3 used in the above-mentioned first embodiment is, for example, an integral glass,
It is made of a transparent synthetic resin or the like, and becomes heavy when the illumination width is as large as about 300 mm. In addition,
In the example shown in FIG. 3, the refracting surface of the cylindrical lens for collimating is generally an aspherical surface (in the case of the first embodiment, it has a hyperbolic shape), and it is difficult to manufacture and the cost tends to increase. There is. In order to avoid such a situation, a second example in which the cylindrical lens 3 is replaced with a cylindrical Fresnel lens 31 is shown in FIG. By doing so, it is possible to realize a system that is lightweight and inexpensive.

The apparatus of this embodiment can be constructed in the same manner as the apparatus of the first embodiment described above, except for the components that employ the cylindrical Fresnel lens 31.

FIG. 6 shows an illumination device according to the third embodiment of the present invention. With respect to the same components as those in the above-described first embodiment, duplicated description will be omitted and only characteristic features will be described.

In this embodiment, the parabolic cylinder surface 2 used in the first embodiment shown in FIGS. 1 to 3 is replaced with an off-axis parabolic cylinder surface 21. With such a configuration, the light flux collimated in the lateral direction can be prevented from being affected by the vignetting of the reflection mirror 5 for preventing stray light.

FIG. 7 shows an illumination device according to the fourth embodiment of the present invention. This embodiment will also be described focusing on the characteristic part. In Examples 1 to 3 described above, the parabolic cylindrical mirror 2 was used as a semi-cylindrical reflecting mirror for collimating the light flux in the lateral direction, assuming that the light source is a perfect point light source. However, since the actual light source has a finite size to some extent, the light beam that is incident on and reflected by the parabolic cylindrical mirror 2 is a light beam that diverges slightly. In order to suppress this effect to a small extent, an example in which an elliptic cylindrical surface slightly displaced from the parabolic cylindrical surface is used instead of the parabolic cylindrical surface will be shown as this embodiment.

In FIG. 7, instead of the parabolic mirror of FIG. 3 shown in the first embodiment, a light source position slightly deviated from the parabolic cylinder surface is used as a first focal point, and a second focal point 10 is used as a scanning reflection shade 4. An ellipse set to be farther than the scanning region is formed as an elliptic cylindrical mirror 22 extending in a cylindrical shape in a direction perpendicular to the light source and the surface including the ellipse. According to this embodiment, the above-mentioned drawbacks are eliminated and the light utilization efficiency can be further improved.

FIG. 8 shows the fifth embodiment of the present invention in relation to the fourth embodiment. This is an example in which the off-axis parabolic cylindrical surface 21 of the third embodiment shown in FIG. 6 is replaced by a similar off-axis elliptic cylindrical mirror 23. Also according to this embodiment, the light utilization efficiency can be further improved. In FIGS. 7 and 8 showing the above-mentioned fourth and fifth embodiments, the second deflecting means is shown by a cylindrical lens 3 having a quasi-line of the approximate parabola of the ellipse (a parabola before shifting) as a focal line. However, a cylindrical Fresnel lens as shown in FIG. 5 may be adopted, and by using a Fresnel lens, the weight and cost can be reduced as described in the second embodiment.

[0026]

According to the present invention having the above-mentioned structure and operation, the reflecting mirror as the first deflecting means for collimating the divergent light emitted from the point light source in one direction and the second for collimating in the vertical direction. By arranging cylindrical lenses as deflecting means independently of each other, the conventional reflecting surface 1 having a paraboloid of revolution (or a surface close to it)
As compared with a system in which collimation is performed at a stretch, the shape can be easily made, and the short and long directions can be independently optimized, so that an efficient lighting device can be provided.

Furthermore, by constructing the cylindrical lens as a cylindrical Fresnel lens from a lens made of glass alone, the effects of weight reduction and cost reduction can be expected.

[Brief description of drawings]

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

FIG. 2 is a plan view showing the first embodiment.

FIG. 3 is a side view showing the first embodiment.

FIG. 4 is a diagram showing a part of the first embodiment modified.

FIG. 5 is a plan view showing an illumination device according to a second embodiment of the present invention.

FIG. 6 is a side view showing a third embodiment of the present invention.

FIG. 7 is a side view showing a fourth embodiment of the present invention.

FIG. 8 is a side view showing a fifth embodiment of the present invention.

FIG. 9 is a perspective view showing a conventional lighting device.

FIG. 10 is a plan view showing a conventional lighting device.

FIG. 11 is a side view showing a conventional lighting device.

[Explanation of symbols]

1 point light source 2 Semi-cylindrical reflector 3 Cylindrical lens 4 Reflector (moving scanning system)

Claims (4)

[Claims] 1. A fixed point light source, a semi-cylindrical reflector having the point light source as a focal point and having a collimating function in one direction, and a light beam emitted from the reflector is collimated. An illuminating device comprising: a cylindrical lens having a collimating function in the other vertical direction, and a moving scanning condensing means for condensing a light beam emitted from the cylindrical lens in an illuminated area. 2. The illuminating device according to claim 1, wherein the reflecting mirror has a semi-cylindrical cross section formed in a parabolic shape. 3. The reflecting mirror is characterized in that its semi-cylindrical cross section is shaped so as to form a part of an ellipse having a point light source position as one focal point. The lighting device according to. 4. The illumination device according to claim 1, wherein the cylindrical lens is formed as a cylindrical Fresnel lens.