JPS6146938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improved lens for a sealed beam light bulb.

[Technical background of the invention and its problems]

Hitherto, commonly used sealed beam light bulbs are constructed so that a predetermined light distribution is obtained by diffusing the direct light from the filament and the reflected light from the reflector using a lens. is normal. This type of light bulb is particularly required to diffuse the projected light at a predetermined angle through a lens, and this has been an important problem in the past.

However, as shown in Figure 1, conventional lenses
Lens element 1 having a convex inner surface except for the center of lens 1
1 is formed in large numbers. This lens element 11 has a substantially circular shape when viewed from the front, and since the light incident on this element 11 is uniformly diffused radially, there is no need to regulate its position with respect to the reflecting surface, which is very preferable.

However, since the thickness of the lens 1 is slightly different between the center of the lens and other parts, some distortion occurs during lens manufacture (by press molding). Although distortion can be removed to some extent through post-processing, it is difficult to remove it completely.
This causes cracks due to heat shock during sealing with the reflecting mirror, lowering yield, and causing damage to the bulb after it is completed. Therefore, it is desirable that the thickness of the entire lens 1 be as uniform as possible;
Since it is necessary to provide 1,..., the difference in wall thickness cannot be avoided.

On the other hand, as described above, this lens 1 is press-molded, but the shape of the mold becomes complicated, and the finished lens 1 has some defects. That is, if the lens elements 11, . However, it is difficult to accurately form a large number of concave portions in a press mold, or the height of the lens element 2 must be increased in order to obtain a predetermined light distribution angle using only the lens element 2. The mold also has to be molded accordingly, making it difficult to manufacture. Further, when press molding is performed, a small amount of air remains in each concave portion of the mold. If this remains as wrinkles or bubbles on the top of each lens element 11 after the lens 1 is molded, light transmission will be poor and the transmittance in this area will decrease, resulting in a decrease in luminous flux. I felt warm and unwell.

[Purpose of the invention]

The present invention is a sealed beam type that has a lens with good diffusion performance that does not cause wrinkles or wrinkles on the lens and has little interference with light transmission, and is also resistant to thermal shock and has improved formability by reducing the difference in wall thickness of the lens. The purpose is to provide light bulbs.

[Summary of the invention]

The present invention relates to a light bulb in which a filament is enclosed in a pulp formed by sealing a lens to an opening of a reflecting mirror, in which the lens is provided with a large number of concave lens elements on its inner surface, and a microscopic structure is formed on the surface of the concave portion. The gist of this invention is a sealed beam light bulb that is characterized by forming an uneven diffusing surface.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to the drawings. Fig. 2 shows a sealed beam type light bulb, in which 2 is a lens reflector, 1 is a glass lens sealed to the front opening of this reflector 2, and by hermetically sealing both, the pulp 3 is formed. In addition, inside the pulp 3, there is a tungsten filament 4, which is a light source, along with an inert gas such as argon or nitrogen.
is included. Note that 5 is a cap attached to the end of the reflecting mirror 2. The lens 1 has a structure as shown in FIGS. 3 and 4. The outer surface of the lens 1 is a smooth curved surface to which little dust adheres, and the inner surface is formed into a curved surface having approximately the same curvature as the outer surface. Further, lens elements 13, . . . consisting of a large number of concave portions are formed around the inner surface of the lens 1, excluding the central portion 12. This lens element 13 is formed in a circular shape when viewed from the top or bottom surface so that all the light passing through this lens element 13 can be equally diffused. Further, a large number of fine rough surfaces 14, . . . are formed on the concave surface of the lens element 13, as shown in an enlarged view in FIG.

With the above configuration, a good diffusion function was obtained even though the difference in wall thickness was small in the same lens 1.

Incidentally, the unevenness of the finely rough surfaces 14, . . . of the lens elements 13, . The reason for this is that if the roughness is less than 1 μHmax, no rough surface will be formed on the surface, and the diffusion effect due to this rough surface will disappear. On the other hand, if the roughness exceeds 70 μHmax, the original shape of the lens element 13 will be distorted and the original diffusion function of the lens will not be exhibited. In experiments conducted by the present inventors, the diffusion effect was good when the surface roughness was in the range of 6 μHmax to 50 μHmax, but it could be put to practical use in the range of 1 μHmax to 70 μHmax.

Note that it is also possible to obtain a diffusion effect by deepening the concave portion of the lens element 13, but in that case, the sixth
As shown in the figure, the difference between the original wall thickness (b) and the wall thickness of the recess (a) becomes large, creating a large difference in wall thickness throughout the lens 1, which makes the lens vulnerable to thermal shock. When sealing 1 and a matching reflector 2,
It is unwell because it causes cracks.

As described above, in the present invention, the difference in wall thickness between the concave portion and the non-concave portion of the lens 1 can be reduced by providing finer rough surfaces on the surfaces of the lens elements 12, . This made it possible to realize this goal.

Next, specific examples will be described. A large number of lens elements 13, which were circular when viewed from the top or bottom, were formed by pressing on the curved inner surface of the lens 1 having a wall thickness of approximately 4 mm. The size of the concave portion of the lens elements 13, . . . is approximately 3.7 mm in diameter and approximately 0.5 mm in depth. Then, a fine rough surface with a roughness of about 6 μHmax was formed on the concave portion surfaces of the lens elements 13, . A reflecting mirror 2 with a filament 4 attached thereto was sealed to the lens 1 thus formed to form a sealed beam type light bulb as shown in the second figure.

Then, in order to confirm the diffusion effect of the lens 1, a red laser beam with a diameter of about 2 mm was applied to the lens element 13.
The transmitted and diffused light was measured by placing a screen approximately 50 cm away. According to this measurement, we were able to obtain a diffusion effect of approximately 0.8 to 2.4 degrees in the radial direction. Compared to the diffusion effect due only to the concave portion of the lens element, this corresponds to when the depth of the lens element is approximately 0.8 mm, and the depth of the lens element can be made sufficiently shallow. In other words, it has become possible to reduce the depth from 0.8 mm to 0.5 mm. Therefore, since the difference in the thickness of the lens can be made smaller, the lens can be made more resistant to thermal shock.

Next, other embodiments will be described. As in the above embodiment, the lens elements 13, . . . were circular, with a diameter of about 3.7 mm and a depth of 0.3 mm. The concave surfaces of the lens elements 13, . . . have roughness of approximately
When the lens 1 was constructed by forming a rough surface of 60 μHmax, it was possible to obtain almost the same diffused light distribution as in the above embodiment. In this case, the lens elements 13,...
The original shape is almost never destroyed. Moreover, it became possible to reduce the depth of the lens elements 13, . . . to 0.3 mm, and good results were obtained.

〔Effect of the invention〕

As described in detail above, the present invention provides a shielded beam type characterized in that a large number of concave lens elements are provided on the inner surface of the lens, and a finely uneven diffusing surface is formed on the concave surface. Since it is a light bulb, the lens element is made into a concave part so that it does not become thicker than the basic wall thickness of the lens, so that the lens flows easily in the mold during press molding of the lens, and it is easy to mold, and there are no wrinkles or bubbles. can suppress the occurrence of Furthermore, since the lens element is concave, the mold has a convex portion, so the mold can be fabricated with high precision and easily. In addition, a rough surface can be easily formed on the mold by electric discharge machining.

Furthermore, in the present invention, the lens element is not only made of a concave portion, but also has a rough surface with fine irregularities formed on the surface of the concave portion to bring about a diffusion effect.
Since the depth of the concave portion of the lens element can be made shallow, that is, the difference in lens thickness is reduced, the occurrence of distortion is reduced, and the thermal shock resistance can be improved.

With this configuration of the present invention, it is possible to provide a sealed beam light bulb that has various advantages, such as excellent light diffusion performance and strength of the lens, and ease of manufacturing and improved productivity. be.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a cross section of a lens used in a conventional light bulb, Figs. 2 to 5 show embodiments of the present invention, and Fig. 2 is a partially cutaway sectional front view of a sealed beam type light bulb. Fig. 3 is an explanatory diagram showing a cross section of the lens, Fig. 4 is a bottom view of the lens, Fig. 5 is an enlarged sectional view of the main part of the lens, and Fig. 6 is a sectional view of the main part to explain the lens configuration. . 1... Lens, 2... Reflector, 13... Lens element (concave portion), 3... Bulb, 14... Diffusion surface, 4... Filament.

Claims (1)

[Scope of Claims] 1. A light bulb in which a filament is enclosed in a pulp formed by sealing a lens in an opening of a reflecting mirror, in which the lens is provided with a large number of lens elements each having a concave shape on its inner surface, and the concave portion A sealed beam light bulb that is characterized by a diffuser surface with fine irregularities formed on its surface. 2 The fine diffusion surface of the concave part of the lens element is 1μ
The sealed beam light bulb according to claim 1, characterized in that it has an uneven surface with a roughness of Hmax to 70 μHmax.