JPH04240841A - Illuminator - Google Patents

Abstract

PURPOSE:To obtain a uniform illuminance distribution on an illuminated surface by arranging a lens array having power on front of a linear light source in the lengthwise and widthwise directions. CONSTITUTION:Light from the linear light source 2 is supplied to a spherical lens array 3 via respective filaments 1A-1E. The focuses of the spherical lens array 3 are on respective filaments 1A-1E, so that luminous fluxes projected from respective filaments 1A-1E, are collimated, to be turned into parallel luminous flux groups A-E, and advances along the surface of an original platen 5. The parallel luminous flux groups A-E are reflected on the original platen 5 by a mobile reflecting member 4, and simultaneously, the surface of the original platen 5 is lighted by the movement of the mobile reflecting member 4. Even if the mobile reflecting member 4 is moved and the parallel luminous fluxes A-E obtain A'-B', the densities of the luminous fluxes are not changed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device used in a copying machine, and more particularly to a fixed type slit exposure device in which a document, a document table, and a light source are fixed to the device.

0002

2. Description of the Related Art Conventionally, a slit exposure apparatus of this type in which a document, document table and light source are fixed has been disclosed in Japanese Patent Application Laid-open No. 54-133140.
There are some disclosed in Japanese Patent Application Laid-open No. 54-42129. FIGS. 5 and 6 are diagrams showing the schematic configurations of these conventional lighting devices. The illumination device shown in FIG. 5 is one in which illumination is arranged on one side of the document.
2 is a reflecting mirror 13 that reflects the light from the linear light source 11;
14 is a document table; 15 is a movable reflecting member; the document 14 is optically scanned by horizontally moving and reflecting the light from the reflecting mirror 12;

On the other hand, the illumination device shown in FIG. 6 is one in which illumination is arranged on both sides of a document, and parts having the same configuration as in FIG. 5 are given the same reference numerals.

0004

However, this conventional technique has a problem in that the illuminance in the peripheral area decreases as the distance from the light source increases.

FIG. 7 shows the decrease in illuminance when illuminated from one side as in JP-A-54-133140, and FIG. 8 shows the decrease in illuminance when it is illuminated from both sides as in JP-A-54-42129. FIG. 3 is a diagram showing a decrease in illuminance, and these diagrams are expressed using isoluminance lines on the document table 13 from above. In the figure, a and b indicate how the light beam emitted from the light source 2 to the side escapes to the outside of the document surface, and the arrowed portion indicates a low-illuminance portion.

[0006] The above-mentioned reduction in illuminance causes a fogging phenomenon in the output image in the copying machine, causing the problem that high-quality copy output cannot be obtained.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to correct the partial decrease in illuminance that occurs depending on the distance from the light source, and to achieve uniform and highly accurate illuminance. The object of the present invention is to provide a lighting device that can provide a wide range of lighting conditions.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a linear light source having a plurality of filaments fixed to an apparatus, and a linear light source having a plurality of filaments fixed to an apparatus, and A lens array having a power and converging light from the filament, and a deflection reflecting member that moves in the lateral direction of the linear light source and directs the light flux from the lens array toward the illumination target medium. Features. In a preferred embodiment, the lens array is constructed by arranging spherical lenses.

Further, the lens array is characterized in that the power in the longitudinal direction of the linear light source is smaller than the power in the lateral direction. Furthermore, such a lens array is constituted by a combination of a spherical lens array and a cylindrical lens, or a toric lens array, or a cylindrical lens array having power in the longitudinal direction of the linear light source, Consists of cylindrical lenses with different powers on the back.

Further, the pitch of the lens array having power in the longitudinal direction of the linear light source is equal to the pitch of each filament of the linear light source.

[0011]

[Operation] According to the present invention, by arranging lens arrays having power in the longitudinal direction and the lateral direction of the linear light source, a group of parallel light beams corresponding to the filament can be obtained.
As a result, a uniform illuminance distribution can be achieved by moving the reflecting member.

0012

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

FIG. 1 is a diagram showing the configuration of a lighting device according to a first embodiment of the present invention, and the lighting device is applied to a copying machine. In the figure, the illumination device according to this embodiment includes a linear light source 2 fixed to the device as a light source for illuminating a document, and a plurality of filaments 1A to 1E arranged in parallel within the linear light source 2. , this filament 1A~1
Corresponding to E, a spherical lens array 3 is arranged in front of the linear light source 2 and has a focal point on each filament, and a spherical lens array 3 is arranged in front of the linear light source 2 and reflects the parallel light beam from the spherical lens array 3. The movable reflecting member 4 optically scans the document by moving in the left-right direction). Note that 5 is a document table placed on the movable reflective member 4, on which a document to be copied is placed.

Next, the operation of the lighting device according to this embodiment will be explained. First, light from the linear light source 2 is supplied to the spherical lens array 3 via each filament 1A to 1E. Since the spherical lens array 3 has its focal point on each filament 1A to 1E, each filament 1A
The light beams emitted from ~1E are collimated and become parallel light beam groups A to E, which proceed along the surface of the document table 5. The parallel light beam groups A to E are reflected onto the document table 5 by the movable reflecting member 4,
At the same time, the surface of the document table 5 is illuminated by the movement of the movable reflection member 4. In this way, in front of the linear light source 2, the spherical lens array having power in the longitudinal direction and the lateral direction of the slit is arranged, so that parallel light ray bundles A to E corresponding to each filament 1A to 1E are obtained. Even if the movable reflecting member 4 moves, the density of the light beams A to E does not change between A to E and A' to E'. Therefore, the illuminance on the document surface illuminated by deflecting these light beams in the cross section is uniform, and is uniform with respect to the movement of the movable reflecting member 4.

Next, a second embodiment of the present invention will be described.

[0016] This embodiment has been developed in consideration of the fact that in the case of a linear light source, the filament is often long in the longitudinal direction, and an example thereof is shown in FIG. As shown in the figure, in consideration of the above-mentioned points, the lens array 3a according to the present embodiment has a finite size by making the R1 plane a plane and the R2 plane a toric shape with different curvatures of the generatrix and sagittarius. It efficiently collimates the filament. In this case, the power of the generatrix (in the longitudinal direction of the slit) is smaller than the power of the daughter wire (in the lateral direction of the slit).

FIGS. 3 and 4 are also examples based on the same idea.

The lens array 3b shown in FIG. 3 is an example in which the R1 surface is a cylindrical lens having power in the short direction of the slit, and the R2 surface is a cylindrical lens having power in the longitudinal direction of the slit.

The lens array 30 shown in FIG. 4 is an example in which the R1 surface is a cylindrical lens having power in the short direction of the slit, and the R2 surface is a spherical lens.

[0020]

[Effects of the Invention] As explained above, according to the present invention,
By placing a lens array with power in the longitudinal and lateral directions in front of the linear light source, a group of parallel light beams corresponding to each filament can be obtained, thereby creating a uniform illuminance distribution on the surface to be illuminated. can give. Therefore, when applied to optical equipment such as a copying machine, it is possible to obtain high-quality images without fogging or the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a lens array of a lighting device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing the configuration of a lens array of a lighting device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing the configuration of a lens array of a lighting device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration example of a conventional lighting device.

FIG. 6 is a diagram showing a configuration example of a conventional lighting device.

FIG. 7 is an isoluminance distribution diagram for explaining problems with conventional lighting devices.

FIG. 8 is an isoluminance distribution diagram for explaining problems with conventional lighting devices.

[Explanation of symbols]

1A, 1B, 1C, 1D, 1E filament 2, 1
1 Linear light source 3 Spherical lens arrays 3a, 3b, 3c Lens array 4 Moving reflective members 5, 13 Original table

Claims (7)

[Claims] 1. A linear light source having a plurality of filaments fixed to an apparatus, a lens array having power in the longitudinal and lateral directions of the linear light source and converging light from the filaments, and An illumination device comprising: a deflection and reflection member that moves in the lateral direction of the linear light source and directs the light beam from the lens array toward a medium to be illuminated. 2. The illumination device according to claim 1, wherein the lens array is composed of a series of spherical lenses. 3. The illumination device according to claim 1, wherein the lens array has a power in the longitudinal direction of the linear light source that is smaller than a power in the transverse direction. 4. The lighting device according to claim 3, wherein the lens array is configured by a combination of a spherical lens array and a cylindrical lens. 5. The illumination device according to claim 3, wherein the lens array is comprised of a toric lens array. 6. The lens array includes a cylindrical lens array having power in the longitudinal direction of the linear light source;
4. The illumination device according to claim 3, comprising a cylindrical lens having different powers on the back surface. 7. The lighting device according to claim 1, wherein the pitch of the lens array having power in the longitudinal direction of the linear light source is equal to the pitch of each filament of the linear light source.