JPH02135606A - Illumination device - Google Patents

Abstract

PURPOSE:To shorten an emitting portion, and efficiently and uniformly illuminate a long-sized subject to be illuminated by providing reflecting mirrors at the back of a light source the emission length of which is shorter than the length of a region to be illuminated, the section of each of the reflecting mirrors being in the form of an ellipse with its focuses one located at near the center of the light source and the other at an end of the region to be illuminated. CONSTITUTION:The emission length l of the emitting portion 2a of a light source 2 is shorter than the length L of the illuminated region of a subject 1 to be illuminated. Reflecting mirrors 3, 4 are both disposed at the back of the light source, and the mirror 3 has its reflecting face 3a on a part of an ellipse the focuses F1, F2 of which are located at near the center of the light source 2 and at one end of the illuminated region, respectively, and the mirror 4 has its reflecting face 4a on a part of another ellipse the focuses F1, F3 of which are located at near the center of the light source 2 and at the other end of the illuminated region, respectively. The distribution of illuminance by light directly falling on the illuminated region without being reflected by the reflecting mirrors 3, 4 and reflecting plates 5, 6 is represented by cosine 4 multiplication. Beams of light reflected by the reflecting mirrors 3, 4 are converged toward respective focuses F2, F3 on the subject 1 to be illuminated, in order to compensate for unevenness in the distribution of illuminance which is caused by the cosine 4 multiplication.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an illumination device for illuminating an illuminated object having a long illuminated area.

(Background of the Invention) As a conventional method for irradiating an illuminated object having a long illuminated area, there are the following methods.

■A light source that has a light emitting part that is approximately the same length as the illuminated object (for example,
method using a fluorescent lamp or halogen lamp).

■How to arrange multiple light sources.

(2) A method of using an optical fiber bundle whose end face shape on the light source side matches the shape of the light emitting part, and whose end face shape on the illuminated object side matches the shape of the area to be illuminated.

(Problems to be Solved by the Invention) However, the method with the above configuration has the following problems.

First, in the method (2): (a) Using a light source having a light emitting part approximately the same length as the object to be illuminated results in poor utilization efficiency of the luminous flux and high power consumption.

(b) When a fluorescent lamp is used as a light source having a light emitting part approximately the same length as the object to be illuminated, it is difficult to obtain high brightness compared to a halogen lamp or a mercury lamp.

(C) When a halogen lamp is used as a light source having a light emitting part that is approximately the same length as the object to be illuminated, the filament in the halogen lamp bulb is also long, so the filament is supported using a retaining ring. Therefore, the temperature of the filament near the retaining ring decreases, the amount of light from the filament near the retaining ring decreases, and the retaining ring forms a shadow, causing unevenness in the amount of light in the longitudinal direction.

Furthermore, when making a halogen lamp long, reducing the power per unit length will increase the luminous efficiency (luminous flux/input power).
It is difficult to increase the height of the light, so the filament is generally of a segment type consisting of a light-emitting part and a non-light-emitting part (short-circuit part). Furthermore, since the short-circuited portion does not emit light, unevenness in the amount of light occurs in the longitudinal direction.

Next, in method ■, (a) The number of parts increases.

(b) Since irradiation is performed using a plurality of light sources, unevenness in the amount of light is likely to occur at the boundary between each light source.

(C) Since light sources have a limited lifespan, as the number of light sources increases, the frequency of replacement increases.

Furthermore, in the method of ■, (a) Optical fibers are generally expensive.

(b) Resin optical fibers are relatively inexpensive compared to glass optical fibers, but resin optical fibers cannot have a very high allowable power density.

The present invention has been made in view of the above-mentioned problems, and its object is to provide lighting that can evenly and efficiently illuminate a long illuminated object using a short light emitting section and a single light source. The goal is to provide equipment.

(Means for Solving the Problems) The invention of claim 1 which solves the above problems provides an illumination device for illuminating an illuminated object whose illuminated area is long, in which a light-emitting portion that is shorter than the illuminated area of the illuminated object is provided. and a reflecting mirror disposed in a direction opposite to the illuminated object with respect to the light emitting part of the light source, and the cross-sectional shape of the reflecting mirror taken along a plane passing through the illuminated area and the light emitting part is A part of a first ellipse whose focus is near one end of the illuminated area and near the center of the light source, and a part of a first ellipse whose focus is near the other end of the illuminated area and near the center of the light source. According to a second aspect of the invention, a light diffuser is disposed near the object to be illuminated, and the light diffuser is used as a secondary light source.

(Function) In the illumination device of the present invention, in claim 1, the light emitted from the light source having the light emitting part shorter than the illuminated area of the illuminated object is a luminous flux that goes directly toward the illuminated object, and the illuminated area and the light emitting part. A cross-sectional shape cut by a plane passing through the first region has a focal point near one end of the illuminated area and near the center of the light source.
and a part of a second ellipse whose focal point is near the other end of the illuminated area and near the center of the light source, and is reflected by a reflecting mirror and directed toward the illuminated object. It can be divided into The light beam reflected by the reflecting mirror and directed toward the illuminated object compensates for the light beam directed directly toward the illuminated object. Further, in claim 2, the light diffuser disposed near the object to be illuminated in claim 1 serves as a secondary light source.

(Example) Next, one embodiment of the present invention will be described using the drawings.

FIG. 1 is a plan configuration diagram illustrating a first embodiment of the present invention;
Figure 2 is a front sectional view in Figure 1, Figure 3 is a diagram explaining the illuminance distribution of only direct light from the light source on the illuminated object in Figure 1, and Figure 4 is the illuminated object in Figure 1. A diagram explaining the illuminance distribution of only indirect light from a light source on the body, FIG. 5 is a plan configuration diagram explaining the second embodiment of the present invention, and FIG. 6 explains the illuminance distribution on the screen in FIG. 5. This is a diagram.

First, in FIGS. 1 and 2, 1 is the illuminated area (L
) is a long object to be illuminated. 2 is a light source having a light emitting section 2a. The light emitting region (ff) of the light emitting section 2a is shorter than the illuminated region (L). Reference numeral 3.4 denotes a reflecting mirror disposed in a direction opposite to the illuminated object 1 with respect to the light emitting portion 2a of the light source 2. The cross-sectional shape of the reflecting mirror 3 taken along a plane passing through the illuminated area of the illuminated object 1 and the light emitting section 2a is such that the vicinity of one end of the illuminated area of the illuminated object 1 and the vicinity of the center of the light source 2 are focused F. , , F is a part of the first ellipse as the reflective surface 3a. Further, the cross-sectional shape of the reflecting mirror 4 taken along a plane passing through the illuminated area of the illumination body 1 and the light emitting part 2a has the vicinity of the other end of the illuminated area and the vicinity of the center of the light source as focal points F, , F, respectively. A part of the second ellipse is used as a reflective surface 4a.

Reference numeral 5.6 denotes a reflecting plate that reflects a part of the luminous flux directed in the vertical direction and directs it toward the object to be illuminated.

Next, the operation of the above configuration will be explained. First, the case where there is no reflecting mirror 3.4 or reflecting plate (that is, the case of direct light) will be explained with reference to FIG. The illuminance distribution of the illuminated area of the illuminated object 1 is expressed by the cosine fourth power law shown in the following equation.

L-LOcos'θ-(1) Here, L: illuminance at any point P in the illuminated area Lo: Brightest in the illuminated area Illuminance at point O θ, ZPF, 0 It is.

Next, the illuminance distribution due to the light beam reflected by the reflecting mirror 3 (that is, in the case of indirect light) will be explained using FIG. 4. In the figure, considering a light beam parallel to the plane of the paper, the light beam emitted from a focal point F on the light emitting section 2a is reflected on the reflecting mirror 3 and reaches a focal point F on the illuminated object 1.

focus on. Further, the light beam emitted from another point Q on the light emitting section 2a is reflected at a point R on the reflecting mirror 3 and is focused on a point f on the object to be illuminated 1.

Here, if zQ RF , −ψ, zfRF, contract ψ
It is.

The angle ψ changes depending on the position of point Q and the position of reflection point R, but in the figure, when reflecting at point R8, it becomes 0,
The light flux heads toward the focal point F2. When the reflection point R is fixed, the angle ψ increases as Q is farther from F, and decreases as Q approaches Fl.

Then, as Q approaches F, the angle ψ becomes smaller, and the reflected light flux concentrates on F2.

Therefore, the illuminance distribution due to the light beam reflected by the reflecting mirror 3 has a peak at F2, as shown in FIG. 4, and has a distribution that expands according to the length of the light emitting section 2a. This means that
The same applies to the reflecting mirror 4.

The characteristic of the illuminance distribution due to indirect light shown in FIG. 4 is a distribution that tends to compensate for the non-uniformity of the cosine fourth power law illuminance distribution due to direct light shown in FIG. Therefore, when the two are combined, the illuminance distribution of the illuminated area of the illuminated object 1 becomes approximately equal.Moreover, the light emitting part 2a of the light source 2 can be shorter than the illuminated area of the illuminated object 1, which is efficient. .

In the above embodiment, although the reflectors 5 and 6 are provided, the illuminance distribution of the illuminated area of the illuminated object 1 increases overall, and the tendency is substantially the same.

Next, a second embodiment of the present invention will be described using FIGS. 5 and 6.

In FIG. 5, reference numeral 11 denotes a ground glass whose illuminated area (L) has light diffusing properties as a long illuminated object. 12
is a light source having a light emitting section 12a. This light emitting part 12a
The light emitting region Cf1) is shorter than the illuminated region (L). Reference numerals 13 and 14 denote reflecting mirrors disposed in a direction opposite to the illuminated object 11 with respect to the light emitting portion 12a of the light source 12. The cross-sectional shape of the reflecting mirror 13 in the longitudinal direction of the illumination body 11 has a focal point F2. A part of the first ellipse F is used as the reflective surface 13a. Further, the cross-sectional shape of the reflecting mirror 14 in the longitudinal direction of the object 11 to be illuminated is such that the vicinity of the other end of the area to be illuminated and the vicinity of the center of the light source are respectively focused at F,
A part of the second ellipse F is used as the reflective surface 14a.

15 is a Fresnel lens provided in close contact with the frosted glass 11. 16 is a reversal film which is a transparent original, 17 is a lens, and 18 is a screen.

Next, the operation of the above configuration will be explained. As described in the first embodiment, the light emitted from the light source 12 is irradiated onto the frosted glass 11 through the Fresnel lens 15 so that the illuminance distribution is uniform. Then, this frosted glass 11 is
The reversal film 16 is illuminated as a secondary light source, and the reversal film 1 is illuminated on the screen 18 by the lens 17.
6 images are projected.

Here, the illuminance distribution on the screen 18 will be explained using FIG. In the figure, the curve ``■'' is the illuminance distribution without the reflecting mirror 13.14, and the curve ``■'' is the illuminance distribution when the reflecting mirror 13.14 is present.

According to such a configuration, even if the light emitting section 12a is short, the illuminance distribution of the image projected onto the screen 18 is approximately equal.
A projected image of good quality can be obtained efficiently.

Then, by placing a long line sensor such as a CCD line sensor at the position of this screen 18 and feeding the reversal film in a direction perpendicular to the plane of the paper in FIG. 5, the image on the reversal film is converted into an electrical signal. can be converted.

Long CCD line sensors have also become popular in recent years. Compared to a small size, the spacing between the elements is larger for the same number of elements, so it is easier to improve the projection resolution. The present invention is also effective for lighting when such a long CCD line sensor is used.

(Effects of the Invention) As described above, according to the invention of claim 1, the light source has a light emitting part shorter than the illuminated area of the illuminated object, and the light emitting part of the light source is arranged in the opposite direction to the illuminated object. a part of a first ellipse whose focal point is near one end of the illuminated area and near the center of the light source; By forming a part of the second ellipse whose focus is near the other end of the illuminated area and near the center of the light source, the light emitting part is short, and moreover, with a single light source, the illuminated area can be long. It is possible to realize an illumination device that can uniformly and efficiently illuminate an illuminated object of about 300 mm in length. Further, according to the invention of claim 2, in the invention of claim 1, a light diffuser is disposed near the object to be illuminated, and the light diffuser is used as a secondary light source, so that the light emitting part is short and simple. It is possible to realize an illumination device that can evenly and efficiently illuminate a long illuminated object with a single light source.

[Brief explanation of the drawing]

FIG. 1 is a plan configuration diagram illustrating a first embodiment of the present invention;
Figure 2 is a front sectional view in Figure 1, Figure 3 is a diagram explaining the illuminance distribution of only direct light from the light source on the illuminated object in Figure 1, and Figure 4 is the illuminated object in Figure 1. A diagram explaining the illuminance distribution of only indirect light from a light source on the body, FIG. 5 is a plan configuration diagram explaining the second embodiment of the present invention, and FIG. 6 explains the illuminance distribution on the screen in FIG. 5. This is a diagram. In these figures, 1... object to be illuminated 2.12... light source 2a, 1
2a... Light emitting part 3.4, 13.14... Reflector 5.6... Reflector plate 11... Frosted glass 15.
... Fresnel lens 16 ... Reversal film 17 ... Lens 18 ... Screen hook 51
β cylinder 2 figure 3 figure 5 figure 6 position on center screen

Claims (2)

[Claims] (1) In an illumination device that illuminates an illuminated object with a long illuminated area, the light source has a light emitting part shorter than the illuminated area of the illuminated object, and the light emitting part of the light source is arranged in a direction opposite to the illuminated object. and a reflecting mirror disposed, the cross-sectional shape of the reflecting mirror taken along a plane passing through the illuminated area and the light emitting part focuses near one end of the illuminated area and near the center of the light source. An illumination device comprising a part of a first ellipse having a focal point near the other end of the illuminated area and near the center of the light source. (2) The lighting device according to claim 1, characterized in that a light diffuser is disposed near the illuminated object, and the light diffuser is used as a secondary light source.