JPH0631605Y2 - Lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a lighting device capable of obtaining a surface light source having a particularly uniform brightness with a surface light source.

[Conventional technology]

In a conventional surface light source illuminating device, a linear light source 2 such as one or more fluorescent tubes is arranged on a flat or curved reflector plate 1 as shown in FIG. The diffusion plate 3 is arranged on the side opposite to the reflection plate.

Among such illuminating devices, for example, an illuminating device using one linear light source has a brightness distribution on the diffuser plate as shown in FIG. The distribution gradually decreases as it goes to, and is not uniform over the entire diffusion plate. In particular, when the light source 2 and the diffusion plate 3 are brought close to each other in order to make the illumination device thin, the light emitted above the light source and directly reaching the diffusion plate causes the luminance of the portion directly above the light source to be particularly large.

Therefore, many attempts have been made to reduce the light traveling upward from the light source so that the brightness on the diffuser plate becomes uniform.

As one of the conventional examples based on this idea
As in the conventional example described in Japanese Patent Publication No. 1-90106, a linear light-shielding portion 10 having a constant width as shown in FIG. 5 is provided in an upper portion (a portion near the diffusion plate) of a fluorescent tube which is a linear light source. It is known that a large number are intermittently provided. In this conventional example, by appropriately selecting the width of each light-shielding portion, the number thereof, the interval between the light-shielding portions, and the like, an illumination device having a relatively uniform luminance distribution is obtained. However, in this conventional example, the luminance distribution is generally as shown in FIG. That is, in this conventional example, a part of the light traveling upward from the light source is blocked by the light shielding portion, the light reaching the central portion of the diffuser plate, which is immediately above the linear light source, is reduced, and the brightness of the central portion is reduced. However, the brightness on both sides adjacent to it is large and the brightness distribution has two peaks, which is not preferable.

As another conventional example, the one described in JP-A-55-133008 is also known. A light quantity adjusting plate 11 having a dot-like light shielding portion 12 such as a black dot as shown in FIG. 6 provided with an appropriate density distribution is arranged between the diffusion plate and the light source. It is intended to obtain a relatively uniform luminance distribution by suppressing the light that reaches the high luminance portion in. In this conventional example, the brightness distribution on the diffuser plate becomes uniform for the time being, but it is difficult to maintain the positioning accuracy between the light source and the light quantity adjusting plate during the assembly of the device, and in the case of using a plurality of light sources, However, there is a problem in that it is difficult to deal with variations in the brightness of the tube surface.

[Problems to be solved by the invention]

The present invention has a structure in which a linear light source is arranged above a reflection plate, and a diffusion plate is arranged on the side opposite to the reflection plate with respect to this linear light source. It is intended to provide a lighting device which is uniform.

[Means for solving problems]

The lighting device of the present invention has a structure in which a linear light source is arranged above a reflecting plate, and a diffusing plate is arranged on the side opposite to the reflecting plate with respect to the linear light source. A low-reflectance portion is formed by, for example, providing a light amount control means for the light source tube and a light-reducing sheet at the bottom of the light source tube, thereby suppressing the brightness of not only the central portion of the diffuser plate but also its adjacent portion. The brightness is made uniform in all parts on the diffusion plate.

According to the present invention, among the light reflected by the portion directly below the light source of the reflector or the periphery thereof, the light traveling toward the central portion of the diffuser is blocked by the dense light tube of the light source, but the light reflected obliquely is This was done by paying attention to the fact that the brightness reaches a part adjacent to the central part of the diffuser plate and becomes relatively large. By reducing the reflected light, the two peaks shown in FIG. The brightness distribution is suppressed to be uniform. That is, the light that goes upward from the light source is slightly reduced by, for example, a light-shielding pattern as a light amount control means provided on the light source tube, and the reflected light immediately below the light source tube that reaches a portion adjacent to the central portion of the diffusion plate is reduced. Then, the brightness was made uniform over the entire diffusion plate.

[Embodiment] Next, an embodiment of the illumination device of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an embodiment of the present invention, in which 1 is a curved reflector, 2 is a linear light source such as a fluorescent tube disposed in the upper center of the reflector, and 3 is an upper portion of the light source 2. The diffuser plates are arranged opposite to the reflector plate 1 and have substantially the same structure as the conventional example. As shown in FIG. 2, reference numeral 4 indicates that the intermittent pattern provided on the upper part of the fluorescent tube 2 which is a linear light source is directly formed on the fluorescent tube by a light shielding material or the transparent sheet is provided with a black light shielding pattern. Is formed on the fluorescent tube. Reference numeral 5 denotes a member having a low reflectance of a sheet made of a light absorbing material or the like, which is provided in the vicinity of the fluorescent plate 2 of the reflection plate 1.

In this embodiment, the amount of light, such as the light beam l ₁ , which goes directly upward from the linear light source 2 is cut off because a part of the light is blocked by the light blocking pattern 4. Further, the light that is reflected in the vicinity of directly below the linear light source 2 and travels obliquely upward like the light ray l ₂ is reflected on the member 5 having a low reflectance, so that the light amount is reduced. Thus, the light that reaches the central portion 3a of the diffusing plate 3 directly upward from the linear light source 2 and the light emitted from the linear light source 2 that is reflected downward and obliquely upward is reflected by the central portion 3a on the diffusing plate 3. The amount of light reaching each of the adjacent portions 3b is reduced, so that the luminance distribution on the diffuser plate 3 is relatively uniform. Here, the light-shielding pattern 4 is not limited to the one shown in the drawing, and for example, each shape may be a rhombus, a shape in which two trapezoids are symmetrically combined, or a lattice-like pattern, or a linear shape with a different length. In addition to the parallel array shape,
The area of the member 5 having a low reflectance is selected by appropriately selecting the shape, the size, the interval, the light transmittance, etc., such as the light shielding surface on the upper surface of the tube so as to sequentially change the light transmittance. By selecting the reflectance, etc., an extremely uniform luminance distribution as shown in FIG. 3 can be obtained.

In this embodiment, the light-shielding pattern 4 is narrowed so that the uppermost part of the fluorescent tube 2 is wider toward the side surface of the fluorescent tube 2, but the shape may be as shown in FIG. However, in the case of a light-shielding pattern as shown in FIG. 5, the light is brighter from the side of the tube to the lower part than the end 10a of the pattern, and the light is darker above the end 10a due to the light-shielding pattern. Since the light amount changes abruptly to some extent at the boundary, this may appear as a line in a direction parallel to the linear light source on the diffusion plate 3. On the other hand, the one illustrated as the embodiment is desirable because the above-mentioned line does not appear at all because the change of the light amount is not abrupt. Further, the member 5 having a low reflectance also has a wavy end as shown in FIG. 2, but may have a linear shape. In this case as well, in the case of a straight line, the reflectance may change relatively sharply at the straight end, so that a line parallel to the light source may appear. However, it is preferable to use a corrugated pattern because the entire plate will be blurred on the diffusion plate 3 and no line will appear. The same effect can be obtained even if the reflectance of the end portion of the member 5 having a low reflectance is continuously changed.

In the illustrated embodiment, the reflector is a curved one, but other reflectors such as a thin box-shaped reflector by joining another reflector inclined to the edge of a planar reflector The present invention can also be applied to a lighting device having a.

[Effect of device]

The lighting device of the present invention can be made thin and has a center on the diffuser plate due to the intermittent light-shielding pattern provided on the upper surface of the tube and the low reflectance portion formed on the reflector plate directly below the tube. This is an extremely thin, uniform-luminance illuminating device in which the luminance of the portion and its adjacent portion can be suppressed and the luminance distribution on the entire diffusion plate can be made uniform.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a perspective view showing a light-shielding pattern and a member having a low reflectance used in the embodiment, and FIG. FIG. 4 is a cross-sectional view of a conventional lighting device, FIG. 5 is a perspective view of a fluorescent tube provided with a conventional light-shielding pattern, and FIG. 6 is a conventional light-shielding plate. Plan views showing other examples, FIG. 7 and FIG. 8 are graphs showing the luminance distribution on the diffusion plate of the conventional lighting device. 1 ... Reflector, 2 ... Fluorescent tube, 3 ... Diffuser, 4 ... Shading pattern,
5 ... Light absorbing sheet

Front page continuation (72) Inventor Haruaki Kitahara 2-30-1 Namiki, Kawaguchi City, Saitama Daiichi Seiko Co., Ltd. (56) References JP-A-55-133008 (JP, A) JP-A-61 -133502 (JP, A) Actual opening Sho 50-3384 (JP, U) Actual opening Sho 61-34188 (JP, U) Actual opening Sho 61-90106 (JP, U) Actual public Sho-39-33435 (JP, Y2 )

Claims (1)

[Scope of utility model registration request] 1. A lighting device in which a linear fluorescent tube is arranged above a reflecting plate, and a diffusing plate is arranged on the side opposite to the reflecting plate with respect to the linear fluorescent tube. A light-absorptive light-shielding pattern is directly provided on the surface of the fluorescent tube from the upper portion to the vicinity of both sides, and a portion having a low reflectance made of a light-absorbing substance or the like is formed on the reflecting plate directly below the fluorescent tube. Lighting equipment.