JPH0721962B2 - lighting equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminaire having a high luminance and a high luminance uniformity ratio, which is used as a backlight of a transmission image display device or the like.

2. Description of the Related Art In a transmissive image display device using an image display element such as a liquid crystal, for example, an illumination fixture as shown in FIG. 4 is used in order to illuminate the image display element brightly and uniformly from the back surface. There is.

That is, the fluorescent lamp 1 is provided below the linear fluorescent lamp 1.
In order to collect light emitted from the lamp efficiently, a reflector 2 and a diffuser 3 are provided so as to surround the fluorescent lamp 1,
By irradiating the diffuser plate 3 provided on the upper part of the fluorescent lamp 1 with the direct light from the fluorescent lamp 1 and the reflected light from the reflective plate 2, a backlight with high brightness and high brightness uniformity is realized. is there.

The appearance of the fluorescent lamp 1 is shown in FIG. In FIG.
4 is the first positive column part, 5 is the second positive column part, 6 is the tube axis of the first positive column part, 7 is the tube axis of the second positive column part,
Reference numeral 8 is a plane (a portion surrounded by a chain double-dashed line in FIG. 5) including the tube axis 6 of the first positive column portion and the tube axis 7 formed by the second positive column portion. As shown in FIG. 5, the fluorescent lamp 1
Is one in which one end of the first positive column portion 4 and one end of the second positive column portion 5 are joined together by using a straight glass tube coated with a phosphor. The positive column portion 5 is parallel. By thus joining one end of the first positive column portion 4 and one end of the second positive column portion 5, the discharge path can be lengthened, and compared with the case where two straight tubular fluorescent lamps are used. It is known that the overall efficiency of contributing to light emission is high.

As shown in FIG. 5, a conventional backlight luminaire includes a tube axis 6 of a first positive column portion and a tube axis 7 of a second positive column portion in order to make the apparatus thinner. Plane 8
Were arranged so as to be parallel to the diffusion plate 3.

Problems to be Solved by the Invention FIG. 6 shows the luminance distribution on the upper surface of the diffusion plate 3 in the X direction (the transverse direction of the tube diameter of the fluorescent lamp 1) in the backlight thus configured. As shown in FIG. 5, the luminance distribution in this direction is high in the central part of the fixture (position A) and gradually decreases toward the end of the fixture (for example, position B). It tends to be seen in general.

As shown in FIG. 7, the brightness is high at the position A on the upper surface of the diffusion plate 3 because the lamp is in the Z direction (the direction in which the backlight is observed, that is, the direction in which the brightness distribution shown in FIG. 7 is measured). The brightness is low at the position B because the fluorescent lamp 1 itself or the diffuser plate is close to the fluorescent lamp 1 itself or the virtual image 9 of the fluorescent lamp 1 caused by the reflector 2 or the fluorescent lamp 1 itself. Because it is far from This trend is
Although it is affected by the diffuse transmission characteristics of the diffuser plate and the shape of the reflector plate, it can be improved by sufficiently separating the fluorescent lamp 1 and the diffuser plate 3 or by forming the reflector plate in a complicated shape. However, in both cases, the thickness of the fixture was not reduced, and the brightness level on the upper surface of the diffuser plate 3 was lowered, so that it was not suitable as a system for a backlight illumination fixture.

As a method to improve the brightness uniformity while keeping the equipment thin,
There is a method of flattening the luminance distribution by locally changing the optical density of the diffusion plate 4 in the high luminance portion due to the contribution of the light emitting portion of the fluorescent lamp. However, even with this method, the decrease in brightness at the edge of the device does not sufficiently improve the brightness distribution even if the shape of the reflection plate is changed, and the optical density of the diffusion plate 4 is locally changed as in the high brightness part. If the luminance distribution is flattened by changing to, there is a problem that the overall luminance level is lowered.

Means for Solving the Problems The fluorescent lamp, the reflection, so that the direction connecting the tube axis of the positive column part in the virtual image of the fluorescent lamp generated by the reflector in the plane crossing the tube diameter of the fluorescent lamp and the observation direction are different Place plates and diffusers.

Function The decrease in brightness at the edge of the backlight light source can be improved.

EXAMPLE FIG. 1 shows a cross-sectional view across a lamp tube diameter and a virtual image 9 produced by a reflector in a lighting device for a backlight according to an example of the present invention. In FIG. 1, the reflection plate 2 and the diffusion plate 3 are arranged so as to surround the fluorescent lamp 1. The bending angle of the reflector is 45 °, and in the fluorescent lamp 1, the straight line connecting the tube axes of the positive column portion of the virtual image 9 generated by the reflector 2 is an angle of 25 ° with respect to the direction (Z direction) for observing the backlight. Are arranged to have.

As shown in FIG. 1, at the position A on the upper surface of the diffusion plate 3 in the central part of the fixture, the fluorescent lamp 1 itself can be seen from the Z direction (direction in which the backlight is observed) as in the conventional example, and at the position B at the end of the fixture. Shows a virtual image of the fluorescent lamp 1 generated by the reflector 2. As described above, in the embodiment of the present invention shown in FIG. 1, the virtual image of the fluorescent lamp 1 generated by the fluorescent lamp 1 itself or the reflecting plate 2 is arranged more densely than in the conventional example in all the fixtures. The brightness distribution is close to uniform.

FIG. 2 shows the luminance distribution in the transverse direction (X direction) of the lamp tube diameter in the lighting fixture according to the present embodiment. As shown in FIG. 2, at the end of the backlight luminaire according to the present embodiment, the decrease in brightness is reduced as compared with the conventional example.

The above effect is obtained by forming an angle φ between the direction connecting the tube axis of the positive column part in the virtual image of the fluorescent lamp 1 generated by the reflector 2 and the direction of observing the backlight (Z direction) on a plane that crosses the lamp tube diameter. Depends on In FIG. 3, the horizontal axis represents the angle φ, and the vertical axis represents the ratio of the fluorescent lamp 1 itself or the sum of the portions where the virtual image 9 cannot be seen from the Z direction with respect to the entire fixture length in the transverse direction of the lamp tube diameter. As shown in FIG. 3, as the angle φ increases, the ratio of the lamp itself or the portion where the virtual image cannot be seen decreases, and the light source approaches a uniform light source on the upper surface of the diffusion plate 3. Similar investigations are performed on the reflection plate 2 for various other shapes, and the fluorescent lamp 1 is arranged between the reflection plate 2 and the diffusion plate so that the angle φ is different by 5 ° or more. It has been confirmed by calculation and experiments that the effect of preventing the decrease in luminance is remarkable.

Since the present invention guides light to a position on the diffusion plate that is not illuminated by the direct light of the lamp by utilizing the virtual image of the reflection plate, the instrument length L in the X direction is the fluorescent lamp tube diameter R and the X direction. It must be larger than the product R · N with the number N of positive column parts included.

In the embodiments of the present invention, the reflector 2 is described as a combination of flat reflectors, but the same effect can be obtained by combining curved reflectors.

In the embodiment of the present invention, the fluorescent lamp in which the ends of the two positive column parts are joined has been described. However, the ends of the plurality of positive column parts are joined and the tube axes of the respective positive column parts are on one plane. The fluorescent lamp thus configured has the same effect.

In the embodiment of the present invention, the fluorescent lamp in which the positive column portion is joined has been described, but it goes without saying that the same effect can be obtained also in a fluorescent lamp in which the discharge column is lengthened by bending the positive column portion. .

EFFECTS OF THE INVENTION In a lighting device for a backlight that uses a fluorescent lamp, a decrease in brightness at the end of the device in the transverse direction of the fluorescent lamp tube diameter is reduced, and the brightness distribution of the light emitting surface can be made uniform.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section in a transverse direction of a lamp tube diameter and a virtual image generated by a reflector in a backlight illuminator according to an embodiment of the present invention, and FIG. 2 is a diffusion of the backlight illuminator according to the present embodiment. FIG. 3 is a diagram showing the luminance distribution in the transverse direction of the lamp tube diameter on the upper surface of the plate, and FIG. 3 is an angle formed by the plane including the tube axis of the positive column portion of the virtual image and the observation direction of the backlight in the fluorescent lamp generated by the reflector. FIG. 4 is a diagram showing an example of the ratio of the entire fixture length in the transverse direction of the fluorescent lamp tube diameter to the total sum of the fluorescent lamp itself or a portion in which a virtual image cannot be seen from the observation direction. FIG. 4 is a configuration diagram of a conventional backlight illuminator, FIG. 5 is a structural diagram of a fluorescent lamp, FIG. 6 is a diagram showing a luminance distribution in a transverse direction of a lamp tube diameter in a conventional backlight luminaire, and FIG. 7 is a conventional backlight. It is a diagram showing a virtual image caused by transverse cross-section and the reflector of the lamp tube diameter in preparative luminaire. 1 ... Fluorescent lamp, 2 ... Reflector, 3 ... Diffuser, 9 ...
... Virtual image produced by reflector

Claims (2)

[Claims] 1. A fluorescent lamp having a plurality of positive column parts, and a reflector and a diffuser surrounding the fluorescent lamp,
The fluorescent lamp, the reflecting plate and the diffusing plate are arranged so that the observation direction is different from the direction connecting the tube axis of the positive column in the virtual image of the fluorescent lamp generated by the reflecting plate in a plane crossing the tube diameter of the fluorescent lamp. Lighting equipment characterized by: 2. An instrument length L across the diameter of the fluorescent lamp tube,
The luminaire according to claim 1, wherein the tube diameter R of the fluorescent lamp and the number N of positive columns included in the transverse direction of the tube diameter of the fluorescent lamp have a relationship of R · N <L.