JPH07245009A - Reflecting mirror for fluorescent lamp of inside illuminating sign - Google Patents

Abstract

PURPOSE:To radiate light at high radiation efficiency and lessen the unevenness of brightness on a screen by making main light beams coming out of a fluorescent lamp tube reach the screen, the reflected light beams cross in front of the fluorescent lamp tube, and the reflected light beams with different incidence angles impinge upon any points on the screen. CONSTITUTION:Cylindrical or ellipse barrel mirror faces having a radius or the major axis larger than the diameter of a fluorescent lamp tube are set symmetrically at proper gap to cross a part of reflected light beams in front of the fluorescent lamp tube. Light beams except those which go toward a screen directly from the fluorescent lamp are reflected in various directions by the cylindrical or ellipse barrel mirror faces composing a reflecting mirror. The directional distribution of the reflected light beams, that is luminous intensity of the reflected light on the screen, can be adjusted by properly setting the radius or the major axis of the cylindrical or ellipse barrel mirror faces and the distance from the symmetric plane. In the figure, 0 stands for the symmetric plane, 1, 1' for inner cylindrical mirror faces having larger radius 3 than the diameter of the fluorescent lamp tube 2, and 4, 4', 5 respectively for the centers of the mirror faces and the screen. The faces 1, 1' are connected with each other by a flat mirror face 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector behind a fluorescent tube in a so-called internal illumination type signboard in which a fixed or variable screen is illuminated from the rear by a fluorescent tube.

[0002]

2. Description of the Related Art In a conventional internally illuminated signboard, the light behind the fluorescent tube is diffusely reflected by a white plane.

[0003]

However, the conventional diffused reflection by the white plane is inefficient and causes uneven illuminance on the screen. Especially, it is remarkable in a black-light internally illuminated signboard that emits a phosphor on a screen using ultraviolet rays.

It is an object of the present invention to improve the efficiency of light and eliminate the uneven brightness on the screen.

[0005]

In order to achieve the above object, in the internally illuminated signboard of the present invention, a mirror surface of a cylinder or an elliptic cylinder having a radius or major axis larger than the diameter of the fluorescent tube is symmetrically arranged at appropriate intervals. By installing and crossing a part of the reflected light in front of the fluorescent tube, the uneven illuminance on the screen was eliminated and the efficiency was improved by specular reflection.

[0006]

In the reflecting mirror configured as described above, the light other than the light directly going from the fluorescent tube to the screen is reflected in various directions by the cylindrical or elliptic cylinder mirror surface. By appropriately selecting the radius or major axis of the mirror surface of the cylindrical or elliptic cylinder and the distance from the plane of symmetry, the direction distribution of reflected light, that is, the illuminance of reflected light on the screen can be adjusted.

[0007]

EXAMPLE An example will be described with reference to the drawings. 0 is a plane of symmetry,
Reference numerals 1 and 1'represent a cylindrical mirror surface having a radius 3 larger than the diameter of the fluorescent tube 2 and having centers 4 and 4 '.
Reference numeral 5 is a screen, and in the embodiment shown in FIG. 1, the cylindrical mirror surfaces 1 and 1'are connected by a flat mirror surface 6.

Directly behind the fluorescent tube 2, that is, with the plane of symmetry set to 0 °, the optical paths of the principal rays emitted from the fluorescent tube are shown in increments of 5 °, and the main angles are indicated.

In both FIG. 1 and FIG. 2, the chief ray emerging from the lateral direction of the fluorescent tube to the front is reflected by the cylindrical mirror surface 1, 1 ', and intersects with other reflected light in front of the fluorescent tube.

[0010]

The effect of the present invention is that in the embodiment of FIG. 1, 310 ° / 360 ° of the chief rays emitted from the fluorescent tube, and in the embodiment of FIG. 2, almost 100% of the chief rays reach the screen. Since the reflected lights intersect at the front surface of the fluorescent tube, the reflected lights having different incident angles hit any point on the screen. Therefore, the efficiency was improved, the uneven illuminance of the screen was reduced, and the uneven brightness with the naked eye was eliminated.

If it is only efficient, a parabolic mirror can be made to the same degree as in the embodiment of FIG. 1, but since the boundary of the reflected light appears clearly on the screen, it can be used for a sign with only one light, but it is a multi-light type. On the signboard, either bright or dark stripes always appear and it is not practical.

In the embodiment shown in FIG. 1, the illuminance is gradually reduced at the boundary of the reflected light, so that in the multi-lamp type signboard, the unevenness of the visible luminance is eliminated by adjusting the intervals of the fluorescent tubes.

In particular, in a signboard using a black light fluorescent tube in which the fluorescent substance on the screen is made to emit light by ultraviolet rays, an efficient, high-luminance and uniform product was obtained.

The same effect can be obtained by using an elliptic cylindrical mirror surface instead of the cylindrical mirror surface.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fluorescent tube, a screen, and a cylindrical mirror surface in an internally illuminated signboard according to an embodiment of the present invention.

FIG. 2 is a transverse cross-sectional view showing an embodiment in which a reflecting mirror is composed only of a cylindrical mirror surface.

[Explanation of symbols]

 0 Symmetrical plane 1,1 'Cylindrical mirror surface 2 Fluorescent tube 3 Radius of cylindrical mirror surface 4,4' Center of cylindrical mirror surface 5 Screen

Claims (1)

[Claims] 1. A partially reflected light of a fluorescent tube having a cylindrical or elliptic mirror surface having a radius or a major axis larger than the diameter of the fluorescent tube, which is placed symmetrically at an appropriate interval and placed at an appropriate position on the plane of symmetry. A fluorescent lamp reflector for an internally illuminated signboard characterized by intersecting in front of the fluorescent tube.