JPS6159329A - Lighting device of copying machine or the like - Google Patents

Abstract

PURPOSE:To reduce the size and weight of a converting means which converts luminous flux into parallel luminous flux and to realize an ideal illuminance distribution by using a Fresnel plate which has two Fresnel reflecting mirrors as the converting means, and arranging a spot light source at its focus position. CONSTITUTION:The Fresnel reflecting plate 2 has the two Fresnel reflecting mirrors 2a and 2b with optical axes 2' and 2'' cemented at both end sides,and spot light sources 1 and 1' are arranged at the focus positions F and F' of the reflecting mirrors 2a and 2b. Then, pieces of luminous flux from the spot light sources 1 and 1' are made into parallel luminous flux 3 by the Fresnel reflecting plate 2 and them converged linearly on an original 6 by a convergent reflecting type optical element 4. Thus, the Fresnel plate 2 is used as the converting means for obtaining the parallel luminous flux, so the size and weight are reduced and a nearly ideal illuminance distribution is realized.

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, causing a very serious problem.

In order to improve the above-mentioned problems, the method described in Japanese Patent Publication No. 53-41976 shown in Fig. 9 and the method described in Japanese Patent Application Laid-open No. 1983-113166 shown in Figs. 10 and 11 have been proposed. ing.

In each of the above examples, the light beam emitted from the 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 one side of the document by a parabolic reflector d or a curved reflector e. It is something that

Problems to be Solved by the Invention However, in the above-mentioned conventional illumination device, the optical system that creates the parallel lines and the optical system that condenses the parallel lines are both curved shapes or thick lenses, making adjustment difficult. In addition to requiring a lot of work, curved reflectors in particular are made of glass material with high surface precision and are heavy. For this reason,
It is necessary to support the curved reflector without generating vibration during scanning, and the supporting means is complicated and expensive.

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

By using a Fresnel reflecting plate having two 7-renel reflecting mirrors as a means for solving the problem and as a means for converting the light beam emitted from the working point light source into a parallel light beam, the converting means can be made light and lightweight. A lighting device for copying machines, etc. that is easy to install and at the same time provides an illuminance distribution close to the ideal distribution.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. In the figure, reference numeral 1.11 denotes a pair of point light sources such as small halogen lamps, which have the same performance. It is located on the side. As shown in Figure @3, the Fresnel reflecting plate 2 is made by laminating two Fresnel reflecting mirrors 2a and 2b having optical axes 21°2'' on both ends, and these Fresnel reflecting mirrors 2α.

The point light sources 1.11 are arranged at the focal positions F and Fl of 2b, and the light beams emitted from the point light sources 1.11 are converted into parallel light beams 3 by the Fresnel reflection plate 2,
The light reaches a condensing reflective optical element 4, such as a parabolic reflector or a Fresnel reflector, which is installed parallel to the Fresnel reflecting plate 2 with an interval therebetween. The reflective surface 4α of the light-condensing reflective optical element 4 is curved obliquely upward,
The parallel light beam 3 that has reached the optical element 4 is reflected toward the document table 5 provided above the optical element 4, and is focused as a linear beam on the copying surface of the document 6 placed on the document table 5. Ru. Further, the light-condensing reflective optical element 4 is moved in the direction of the arrow along the lower surface of the document table 5 by a drive system (not shown), while scanning the document 5 and illuminating it.

In the above configuration, the Fresnel reflection lights 2a and 2b with a focal length of 168.5 mm are arranged so that the optical axes 2+ and 21 are located at the lower ends of the four corners, and the length is 159rrLrn% and the width is 80m.
The Fresnel reflector plate 2 shown in FIG. 3 was constructed by cutting two pieces into 2 m pieces and pasting them together symmetrically at the center, and using a parabolic reflector as the optical element 4.
The illuminance distribution shown in the figure was obtained. The sudden drop in illuminance distribution in the central area is caused by the light opaque area created by the joint between the 7-Resnel reflectors 2a and 2b.In order to improve this, the Fresnel reflectors 2a and 2b are shown in Fig. 5. When cut diagonally and pasted as shown in FIG. 6, an illuminance distribution close to the ideal distribution indicated by the dotted line was obtained, as shown in FIG. Incidentally, FIG. 7 shows the illuminance distribution of a conventional illumination device, and it can be seen that the illuminance distribution has been significantly improved compared to this. FIG. 8 shows another embodiment in which a portion of the 7-ray reflective plate 2 is removed in order to correct the illuminance distribution.

Effects of the Invention As described in detail above, the present invention uses a 7-Resnel reflecting plate having two Fresnel reflecting mirrors as a means for converting the luminous flux emitted from a point light source into a parallel luminous flux, and the focal point of these Fresnel reflecting mirrors is By providing a point light source at a certain position, an illuminance distribution close to the ideal distribution can be obtained, and by using a lightweight and thin Fresnel reflection plate, support against vibrations during scanning can be achieved using conventional glass materials. It can be constructed easily and inexpensively.

[Brief explanation of drawings]

Fig. 1 is a plan view showing one embodiment of the present invention, Fig. 2 is a side view of the same, Fig. 3 is a front view of the Fresnel reflection plate, and Fig.
The figure is a line diagram showing the same illuminance distribution, Fig. 5 is a front view showing another embodiment of the Fresnel reflection plate, Fig. 6 is a line diagram showing the same illuminance distribution, and Fig. 7 is a line diagram showing the conventional illuminance distribution. 8 is a perspective view showing another embodiment using a correction plate, and FIGS. 9 to 11 are explanatory views of the conventional method. 1.11 is a point light source, 2 is a Fresnel reflection plate, 2a,
2b is a Fresnel reflector, and 6 is a manuscript. Ushikankai Tsubasa Nokankai/father-in-law Figure 7 Figure 8

Claims (1)

[Claims] In the device that illuminates the original 6 by converting the luminous flux emitted from the point light source 1 into a parallel luminous flux and condensing the light in a line onto the original 6 by a reflecting means, the luminous flux emitted from the point light source 1 is converted into a parallel luminous flux. A Fresnel reflection plate 2 having two Fresnel reflection mirrors 2a and 2b is used as a conversion means, and point light sources 1 and 1^1 are arranged at focal positions F and F^1 of the Fresnel reflection mirrors 2a and 2b, respectively. Lighting equipment for copying machines, etc.