JPH0373189B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an illumination device suitable as a light source for a reading device such as a facsimile machine or a copying machine.

Conventionally, as shown in FIG. 1, this type of illumination device focuses light a emitted from a bar-shaped light source (for example, a fluorescent lamp) 1 onto an original 2, and optically converts the reflected light b from the original 2. By making the light incident on an optical reading device, the optical reading device can read characters, designs, etc. on the surface of the original 2.

However, as shown in FIG. 2, part of the light a emitted from the light source 1 is reflected by the surface of the document 2 and enters the reading device 3, and the remaining light is reflected by the surface of the document 2. The light was scattered at the center and became stray light c. As a result, the illuminance of the surface of the document ₂ to the reading device ₃ is insufficient, and as shown in FIG. In some cases, it was necessary to arrange them.

SUMMARY OF THE INVENTION An object of the present invention is to provide an illumination device that returns light scattered in directions other than the reading device on the document surface to the focal position of the reading device on the document surface, thereby improving the illuminance at the focal position. There is a particular thing.

Hereinafter, the present invention will be explained with reference to Examples. Reference numeral 4 denotes a light source consisting of a plurality of fluorescent lamps or high-intensity light emitting diodes arranged in a row, and the light from there is projected onto the focal position of an optical reading device to be described later on the upper surface of the original 5 and its vicinity. ing. Reference numeral 6 denotes an optical reading device having a photoelectric conversion element that reads the contents of the original 5 by light reflected from the surface of the original 5. Reference numeral 7 denotes a concave reflective surface disposed on the opposite side of the light source 4 with respect to the reading device 6 . The reading device 6 then focuses on the concave surface 7a of the reflective surface 7 on the surface of the original 5.
The position A is 1/2 of the radius of curvature r.

According to this embodiment, among the light emitted from the light source 4 and reflected by the surface of the original 5, not only the light in the normal direction of the concave surface 7a of the reflective surface 7 but also the light in the direction parallel to the normal is brought into focus. It is reflected again to position A and returns. In other words, most of the light reflected by the concave surface 7a returns to the focal position A. Therefore, the illuminance at the focal position A will increase significantly.

FIG. 5 shows another example, in which a flat reflective surface 8 is used. In this case, the optical axis angle θ ₁ and the reflected optical axis angle θ ₂ of the light source 4 with respect to the surface of the original 5 are θ ₁
= θ ₂ , the reflecting surface 8 is arranged so that the reflecting surface is orthogonal to the reflected optical axis angle θ ₂ . As a result, the strongest portion of the reflected light on the reflective surface 8 returns to the focal position A, and the illuminance at that position A increases.

As described above, in the present invention, most of the light scattered on the document surface or the strongest part returns to the focal position of the reading device on the document surface by the reflective surface, so that the illuminance at the focal position is reduced. Therefore, there is no need to use a special high-intensity light source, and there is no need to use two light sources as in the conventional case.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional lighting device. FIG. 2 is an explanatory diagram of the operation of the device. FIG. 3 is a perspective view of the conventional device using two light sources. FIG. 4 is an explanatory diagram of a lighting device according to an embodiment of the present invention. FIG. 5 is an explanatory diagram of the same apparatus according to another embodiment. 4... Light source; 5... Original; 6... Optical reader; 7, 8... Reflective surface.

Claims (1)

[Scope of Claims] 1. Light from a light source is made to enter the focal position and the vicinity thereof on the document surface of the optical reading device, and the reflected light at the focal position and the vicinity thereof is returned to the focal position by a reflective surface. A lighting device characterized by: 2. The lighting device according to claim 1, wherein the reflective surface is a flat surface or a concave surface.