JPS6159327A - Lighting device of copying machine or the like - Google Patents

Abstract

PURPOSE:To reduce a converting means and a reflecting means for parallel luminous flux in thickness and weight and to simplify a support structure by making luminous flux from a spot light source into parallel luminous flux through a transmission type Fresnel lens and then converting it linearly on an original surface through a Fresnel reflecting mirror. CONSTITUTION:The spot light source 1 like a small-sized halogen lamp is arranged at the focus position of the plane transmission type Fresnel lens 2 and the Fresnel reflecting mirror 4 which has numbers of extremely small reflecting surfaces in parallel to the lens 2 is provided. Then, the luminous flux from the light source 1 is made into parallel luminous flux 3 by the Fresnel lens 2 and converged linearly on an original 6 through the Fresnel reflecting mirror 4. Thus, the parallel luminous flux converting means and reflecting means use the Fresnel lens 2 and Fresnel reflecting mirror 4, so the size and weight are reduced and its support structure is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an illumination device for a copying machine or the like that illuminates a document to be copied while scanning it.

2. Description of the Related Art A scanning illumination device used in a conventional copying machine illuminates a document by moving a light source along the document to be copied. However, with this method, the life of the light source is short, as the lamp used for the light source is easily burnt out due to vibration or shock during movement, and the light source moves directly under the document table, so copies are made with the document table cover open. In this case, the light directly entered the eyes of the workers, creating a very dazzling problem.

To improve the above-mentioned defects, there are methods described in Japanese Patent Publication No. 53-41976 shown in Fig. 7, as well as those shown in Fig. S and 9.
The method described in Japanese Unexamined Patent Application Publication No. 113166/1983 as shown in the figure has been proposed.

In each of the above, the light beam emitted from a point light source α is made into a parallel light beam using a reflector b or a collimator lens C, and this light beam is focused linearly onto the surface of the document f by a parabolic reflector d or a curved reflector C. It is something.

Problems to be Solved by the Invention However, in the above-mentioned conventional illumination device, the optical system for producing parallel light beams and the optical system for condensing the parallel light beams both have curved shapes and are thick lenses. In addition to requiring a lot of effort for adjustment, the curved reflector in particular uses a glass material with high surface precision, and the amount of M is heavy. For this reason, it is necessary to support the curved reflector without photographing during scanning, and the supporting means becomes complicated and expensive.

This invention was made for the purpose of improving the above-mentioned problems.

By using a Fresnel lens and a Fresnel reflector as a means for solving the problem, a means for converting the light beam emitted from the action point light source into a parallel light beam, and a means for condensing the parallel light beam into a line on the document surface. , lighting devices for copying machines, etc. that are thinner and lighter and easier to install.

Embodiment One embodiment of the present invention will be described in detail with reference to the drawings. In the figure, 1 indicates a point light source such as a small halogen lamp, and 2 indicates a large-area flat plate-shaped transmissive Fresnel lens. The point light source 1 is installed at one focal position.

The light beam emitted from the point light source 1 is converted into a parallel light beam 3 by a Fresnel lens 2, and a Fresnel reflecting mirror 4 is installed parallel to the Fresnel lens 2 with a space therebetween.
reach. As shown in FIG. 2, the Fresnel reflecting mirror 4 has a large number of minute reflecting surfaces 4α that converge parallel light beams into a line. The light is focused as a linear beam onto an original 6 on an original table 5 placed above the original.

Further, the Fresnel reflector 4 is moved along the lower surface of the document table 5 in the direction of the arrow by a drive system (not shown), while the document 6 is being moved in the direction of the arrow.
It scans and illuminates it.

In the above structure, the transmission type Fresnel lens 2 with a focal length of 137 mm is cut into a size of 2781 J in length and 70 m in width with its optical axis 2α located at the center of the flat plate, and the obtained Fresnel lens is formed. I 2 V at the focal position of 2
A point light source 1 consisting of a small halogen lamp (100 W) was installed.

As a result, the light emitted from point light source 1 is Frene/L/L/
The lens 2 converts the light into a parallel beam 3 that reaches the Fresnel reflector 4, but it is projected slightly wider than the area of the Fresnel lens 2, and the peripheral part is colored, so in order to avoid that part and reflect, the length 260+u, A Fresnel reflector 4 with a width of 70IIj was used. In addition, the Fresnel reflector 4 has a reflective surface 4
A large number of α's are formed in parallel at a pitch of 0.5 + u in the longitudinal direction, and approximately 50 mm in the width direction. It has a focal length of ul. The parallel light beam 3 reflected by the reflective surface 4α of the Fresnel reflector 4 is condensed linearly onto the 6th surface of the document on the document table 5 with a half width of about 25 m, and the illuminance distribution in the scanning direction at that time is Figure 3 shows the illuminance distribution in the document width direction, and Figure 4 (a) shows the illuminance distribution in the document width direction.
It was as shown.

On the other hand, in the above embodiment, the illuminance distribution was high at the center and low at the periphery, but in order to correct this, a Fresnel lens was used.
A light shielding plate 7 as shown in FIG. 5 was provided at the bottom of the screen. As a result, the illuminance distribution could be averaged as shown in Figure 4 (b). Furthermore, as shown in FIG. 6, a concave spherical reflector 8 with a radius of 50 mm was attached behind the point light source 1 with its center of curvature aligned with the filament of the point light source 1. It was possible to increase the brightness by 1.7 times compared to the case without the 7-rector, and uneven illuminance was also improved.

Although a small halogen lamp was used as the point light source 1 in the above embodiment, a light source with a small light emitting area such as a high pressure mercury lamp, a xenon short arc lamp, or a metal halide lamp may also be used.

Effects of the Invention As described in detail above, the present invention uses a transmission type Fresnel lens as a means for converting the light beam emitted from a point light source into a parallel light beam, and as a reflection means for condensing the parallel light beam into a line on the surface of the document. Since the Fresnel reflecting mirror is used, it is thinner and lighter than conventional reflecting mirrors, so the means for supporting vibrations during scanning is simple and easy, and can be provided at low cost.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a side view, FIG. 2 is an enlarged side view of a Fresnel reflector, FIGS. 3 and 4 are diagrams showing illuminance distribution, and FIG. 5 is a shading diagram. Explanatory diagram of the board, No. 6
The figure is a perspective view showing another embodiment, and FIGS. 7 to 9 are explanatory views of the conventional method. 1 is a point light source, 2 is a Fresnel lens, 4 is a Fresnel reflector, and 6 is a manuscript.

Claims (1)

[Claims] After converting the light beam emitted from the point light source 1 into parallel light beams, the light beam is focused linearly onto the document 6 by a reflecting means to illuminate the document 6. An illumination device for a copying machine or the like in which a Fresnel lens 2 converts the parallel light beam into a parallel light beam, and a Fresnel reflector 4 focuses the parallel light beam onto a document 6 surface in a linear manner.