JPS6364029B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluorescent lamp in which brightness unevenness is improved by improving the shape of a reflective film.

Conventional fluorescent lamps, for example in flat fluorescent lamps, have a phosphor layer on the inner surface, as shown in Figure 1.
The peripheries of the molded glass containers 2 and 3 coated with a uniform coating are adhered, and electrodes 7 consisting of a filament support wire 4, a tungsten filament 5, and a glass bulb 6 are welded to both ends of the glass containers 2 and 3. While the other end of the wire 4 is connected to the base pin 8, a predetermined amount of mercury and inert gas is sealed in the discharge space 9 in the molded glass containers 2 and 3, and the electrical circuit is as shown in FIG. The electrodes 10 are connected to each other through a load 11, and the starter 12 is connected between the electrodes 7.

When the fluorescent lamp 13 is turned on, a so-called hot spot is generated between the two electrodes 7, and a discharge is started and maintained at the shortest distance between the two electrodes. , 3 is not diffused over the entire area but is concentrated in the center, which causes the problem that the brightness becomes high only in the center, resulting in so-called uneven brightness. In addition, as shown in FIG. 2, in order to control light distribution, there are some cases in which a reflective film 14 made of titanium dioxide or the like is formed between the inner surface of one molded glass container 2 and the phosphor 1; It has not yet been possible to completely eliminate uneven brightness.

The present invention eliminates these conventional drawbacks, controls the distribution of excited visible light by improving the shape of the reflective film, makes the inner surface of the lamp emit light uniformly, and prevents uneven brightness. The purpose is to provide a new fluorescent lamp.

Hereinafter, one embodiment of the present invention will be explained according to the drawings. Fig. 4 shows a cross section perpendicular to the tube axis direction of a flat fluorescent lamp, and the cross section with the inner surface coated with the phosphor 1 is approximately U-shaped. The horizontal bent part 2a of the molded glass container 2, whose inner surface is coated with a reflective film 14 made of phosphor 1 and titanium dioxide, etc., is adhered to the horizontal bent part 3a of the molded glass container 3 using a low melting point vitreous adhesive or the like. There is.

The molded glass container 2 forms an inclined light emitting surface 2b in which the base of the horizontal bent portion 2a is bent inward at an angle of θ ₁ with respect to the horizontal plane, and the upper end of this inclined light emitting surface 2b is bent inward with respect to the horizontal plane at an angle of θ ₄ An inclined light emitting surface 2c is formed which is bent at an angle, and the cross section is symmetrical with respect to a vertical line passing through the discharge center (light source center) O located in the discharge space 9 in the figure.

According to the inventor's experiments, the relationship between θ ₁ and θ ₄ is as follows:
In FIG. 4, the curved light emitting surface 3 of the molded glass container 3
b Horizontal distance between both ends is 2L (mm), molded glass container 3
Assuming that the horizontal distance d (mm) between the end of the curved light emitting surface 3b and the bent part of the horizontal bent part 3a is, It is desirable to set θ ₁ so that the relationship holds true,
Furthermore, it was confirmed that it is optimal to set θ ₄ =5° to 10°.

In addition, in the figure, θ ₂ indicates the angle formed by the upper end R of the inclined light emitting surface 2b of the molded glass container 2 and the center portion Q of the curved light emitting surface 3b of the molded glass container 3,
θ ₃ indicates the angle that the extension line of the inclined light emitting surface 2b makes between the upper end R of the inclined light emitting surface 2b and the discharge center O, and according to the inventor's experiment, there is a difference between θ ₂ and θ ₃ . It was confirmed that it is optimal to set θ ₂ and θ ₃ such that the relationship θ ₂ =θ ₃ holds true.

Next, the shape of the reflective film according to the present invention was confirmed by the inventor's theory and experiments as described below. That is, ABCD in Fig. 5a shows a cross section of the glass container of a flat fluorescent lamp taken at a cut plane perpendicular to the tube axis direction. When the discharge center (light source) O is set on the perpendicular bisector,
Experiments have confirmed that it is optimal to form virtual image light sources 0′, 0″ on the extension line of AB and CD.In order to obtain virtual image light sources 0′, 0″, virtual image light sources 0° P that satisfies PO=P0' at the perpendicular bisector of the straight line 0'O connecting the discharge center O,
A half-line connecting the above A with a straight line and starting from A
All you need to do is find APX, and in the same way, find the reflective mirror surface DX starting from point D. In this reflective mirror surface DX, the angle ∠OAX (θ ₁ ) of the reflective mirror surface for obtaining the virtual image light source 0' at the discharge center O is 45° according to the law of reflection. However, in actual reflective flat lamps,
As shown in FIG. 4, if the horizontal distance between both ends of the curved light emitting surface 3b is 2L (mm), and the horizontal distance between the end of the curved light emitting surface 3b and the bent part of the horizontal bent part 3a is d (mm),
As mentioned above, to obtain the virtual image light source 0' with the discharge center 0, θ ₁ = 45° = tan ^-1 L/L (distance L (mm) of OX in Fig. 5a), therefore, the horizontal distance When becomes L + d, if θ ₁ = tan ^-1 L/L + d, the brightness near point B will increase, so the most suitable angle ∠OAX (θ ₁ ) between the above two is experimentally determined. ,
As a correction for horizontal distance d (mm) A preferable brightness was obtained by selecting the value of θ ₁ as follows.

Next, the electron beam emitted from the discharge center O is BC
In order to avoid focusing on the center Q of
Angle of incidence on APX ∠OPX and reflective mirror surface APX
Find the point R where ∠ORX = ∠QRA is established between the angle ∠QRA formed by the reflected electron beam passing through the center Q of BC, and the reflecting mirror surface APX
cutting or bending. Even in reflective mirror DX
Similarly find R' and cut or bend. This point R
is selected so that the light from the virtual image light source 0' increases the brightness on the left side in the drawing from the center Q, especially in order to increase the brightness near B. Therefore, the left half of the inclined light emitting surface 2c was selected to increase the brightness of the left half of the curved light emitting surface 3a, and similarly the right half of the inclined light emitting surface 2c was selected to increase the brightness of the right half of the curved light emitting surface 3a.

Furthermore, the electron beam emitted from the discharge center O
In order to avoid focusing on the center Q of BC,
As shown in Figure c, the reflective mirror surfaces APX and DX are bent inward with the boundaries R and R', and the bending angle is set at an experimental value of 5° to 10° with respect to the horizontal plane.
This angle θ ₄ is an angle for reflecting the light from the discharge center O toward the end of the lamp, and was determined experimentally in consideration of the moldability of the glass.

Based on the above theory and experimental values, the shape of the reflective film 14 in the above-mentioned example was determined.

FIG. 6 shows the experimental results of measuring the surface brightness distribution of the curved light emitting surface 3b in the molded glass containers of the reflective flat plate lamp of the present invention and the conventional reflective fluorescent lamp. The surface brightness distribution of the reflective flat lamp of the present invention is represented by the (a) curve, and the surface brightness distribution of the conventional reflective fluorescent lamp is represented by the (b) curve, with the inner tube width of the lamp being taken as the axis. In this experiment, both
The experiment was carried out by setting 2L=100 mm, d=5 mm, the vertical distance l between the center Q of the curved light emitting surface 3b of the molded glass container 3 and the discharge center O to l=20 mm, and the distance between the electrodes to 260 mm. From this experimental result, it was found that in the lamp of the present invention, the luminous intensity is almost uniform over the entire area of the light emitting surface, whereas in the conventional lamp, the light is focused directly below the discharge center O, and the luminous intensity varies markedly depending on the position of the light emitting surface. Confirmed In this experiment, the radius of curvature of the curved light emitting surface was 400 mm. This radius of curvature is small,
For example, when the radius of curvature is around 100 mm, the brightness at the center is higher than the surrounding area, and when the radius of curvature is around 400 mm to 500 mm, the brightness is almost uniform over the entire curved light emitting surface.
If it becomes about 1000 mm, problems will arise regarding the brightness of the glass container.

In the above-described embodiment, the shape of the reflective film was mainly explained, but since the lighting method and electric circuit are the same as those of the conventional example, a description of their operation will be omitted.

As described above, the present invention provides a specially shaped reflective film on the fluorescent lamp container, such as a molded glass, to make the brightness of the light emitting surface uniform over the entire area, thereby eliminating the brightness unevenness of conventional fluorescent lamps of this type. This has the effect of providing a high-quality lighting fixture, and since the shape of the reflective film is simply a bent container, there is an advantage that the container can be manufactured.

[Brief explanation of drawings]

Figure 1 is a perspective view of a conventional fluorescent lamp; Figure 2 is a perspective view of a conventional fluorescent lamp;
The figure is a longitudinal side view near the line X-X' in Figure 1.
FIG. 3 is a circuit diagram of a fluorescent lamp, FIG. 4 is a vertical side view of a fluorescent lamp showing an embodiment of the present invention, and FIG. 5 is a conceptual diagram showing a procedure for deriving the shape of a reflective film according to the present invention. FIG. 6 is an experimental diagram showing the effect of the fluorescent lamp according to the present invention in comparison with a conventional lamp. 1... Phosphor, 2, 3... Container, 14... Reflective film.

Claims (1)

[Scope of Claims] 1. In a flat fluorescent lamp in which a pair of containers are coupled together facing each other, a first container having a reflective film on its inner surface has horizontal bends protruding outward approximately horizontally at both ends thereof. 2a, and an inclined light emitting surface 2b bent inward at a first angle θ ₁ with respect to the horizontal bent portion 2a, and an inclined light emitting surface 2b bent inward with respect to the horizontal surface at an upper end portion of the inclined light emitting surface 2b. The second container has _a horizontal bent portion corresponding to the horizontal bent portion 2a of the first container. 3a, a first container comprising the inclined light emitting surface 2b, a curved light emitting surface 3b facing the inclined light emitting surface 2b on both sides thereof, and a bent portion connecting the curved light emitting surface 3b and the horizontal bent portion 3a; The angle between the upper end of the inclined light emitting surface 2b and the center of the curved light emitting surface 3b of the second container is θ ₂ , and the extension line of the inclined light emitting surface 2b is at the upper end of the inclined light emitting surface 2b, When the angle formed with the discharge center is θ ₃ , θ ₂ =θ ₃ , and the first angle θ ₁ is the horizontal distance between both ends of the curved light emitting surface 3b.
2L (mm), and the horizontal distance of the bent part is d (mm), A fluorescent lamp characterized in that the second angle θ ₄ is set at 5° to 10°.