JPS6250944B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a sealed beam light bulb with an improved lens element. [Technical background of the invention and its problems] Generally used diffused sealed beam light bulbs for projecting light diffuse the light from the filament that hits the reflective surface of the reflector using a lens. Usually, the light source is constructed so that a predetermined light distribution can be obtained. This light bulb is particularly required to have visible light emitted from a reflective surface through a lens be diffused at a predetermined angle by the lens, and this has been a problem in the past. However, in the conventional lens, as shown in FIG. 1, a large number of protruding lens elements 11, . . . are formed on the inner surface of the lens 1 except for the center thereof. These lens elements 11,... are approximately circular when viewed from the front (top) or back (bottom), and these elements 11,...
Since the light incident on the reflective surface is uniformly diffused and diffused in a radial manner, there is no need to regulate the position relative to the reflective surface, which is very preferable. However, since the thickness of the lens 1 is slightly different between the center and other parts, some distortion occurs during lens manufacturing (by press molding). These distortions can be removed to some extent through post-processing, but it is difficult to remove them completely, so they may crack due to thermal shock during sealing with the reflector, lowering the yield, or causing damage to the bulb after it is completed. This is the cause of Therefore, lens 1 should be used as much as possible.
Although it is desirable that the overall thickness be uniform, since it is necessary to provide the lens elements 11, etc., the occurrence of thickness differences cannot be avoided. On the other hand, as explained earlier, this lens 1 is press-molded, but in this case, the shape of the press mold becomes complicated, wrinkles are formed on the finished lens 1, or residual air remains on the lens 1 as bubbles. Difficulties arise. That is, when the lens 1 has a convex shape, many recesses are formed in the press mold, but it is difficult to form these recesses accurately on a flat surface, or the lens element 1
Element 1 to obtain a predetermined light distribution angle only with 1,...
Since the height of 1,... must be increased, the mold is also formed accordingly, making it difficult to manufacture the mold. Furthermore, when pressed, a small amount of air remains in the recesses of each mold. This is lens 1
If foam remains on the top of each lens element 11, . . . , the transmission of light is poor and the transmittance at this portion is reduced, resulting in a disadvantage that a decrease in luminous flux is likely to occur. [Object of the Invention] The present invention provides a lens with good diffusion performance, which does not cause wrinkles or wrinkles on the lens, has little interference with light transmission, is resistant to thermal shock, and has improved moldability by reducing thickness differences in the lens. An object of the present invention is to provide a sealed beam type light bulb having the following characteristics. [Summary of the Invention] The present invention relates to a lens having a lens element formed by press molding to form a smooth curved surface on the outer surface and a plurality of substantially spherical concave portions spaced apart from each other on the inner surface, and a light source. A sealed beam light bulb characterized by a sealed beam with a reflector attached to it.'' [Embodiments of the Invention] Examples of the present invention will be described with reference to FIGS. 2 and 3. 1 is a press-molded glass diffuser (flat type) lens with a diameter of approximately 123 mm, and its outer surface has a smooth curved surface that attracts little dust. In addition, a window 12 is formed in the center of the inner surface,
Around this window 12, a large number of lens elements 13, . This lens 1 has a large number of lens elements 13, . . . provided on the inner surface of the lens by excavating it so that it does not become thicker than the basic wall thickness. For example, when the wall thickness of the lens 1 is about 4 mm, the lens elements 13, . . . has a spherical shape with a diameter of approximately 4.0 mm and a depth of approximately 0.8 mm, and is circular when viewed from the front (top) or back (bottom). Furthermore, a step portion 1 is provided on the outer peripheral edge of the lens 1 to prevent the engagement between the two from moving in the radial direction when sealing with the reflecting mirror.
4 is formed. FIG. 4 shows a sealed beam light bulb according to the present invention, in which 2 is a glass reflector, 3 is a tungsten coil filament that serves as a light source and is attached to the base of reflector 2, and the front opening of reflector 2 is A bulb 4 is formed by hermetically sealing the lens 1 to the portion. Note that this valve 4 is filled with an inert gas such as argon or nitrogen.
Further, 5 is a cap attached to the end of the reflecting mirror 2. The present invention provides a lens 1 having the above-mentioned structure, in which a large number of lens elements 13, . is obtained. Further, the lens 1 has a large number of lens elements 1.
3, . . . are formed to be rotationally symmetrical, and a stepped portion 14 having no convex (and concave) engagement key for alignment is formed at the peripheral sealing portion of the lens 1 and the reflecting mirror. Therefore, since the light distribution is approximately circular and the light emission is the same in any direction with respect to the rotational direction of the lens 1, there is no need for regulation in the circumferential direction of the lens 1, making it easy to manufacture the lens 1. Become. In addition, in experiments conducted by the present inventors, defects such as bubbles and wrinkles occurred during lens molding, and defects occurred during sealing work with a reflecting mirror for conventional lenses with a convex surface formed on the inner surface and the present lens with a concave surface formed on the inner surface. The occurrence of crack defects is as follows, and with the configuration of the present invention, the number of defects was reduced. The lens has an outer diameter of approximately 123mm.
The wall thickness at the center is approximately 4 mm.

〔Effect of the invention〕

As described in detail above, the present invention is constructed by sealing and assembling a lens having a plurality of substantially spherical concave lens elements spaced apart from each other on its inner surface and a reflecting mirror having a light source attached thereto. This is a sealed beam type light bulb characterized by the fact that the light that enters and passes through the lens element on the inner surface of the lens is evenly diffused and radiated to the outside of the lens, and a transparent part is formed between each of the above-mentioned concave parts. To obtain a light bulb with good diffused light distribution that does not make the lens surface sparkle when the light bulb is on or off, and is not unsightly for advertising lighting, window lighting, etc. In addition, since the lens element is made into a recess with an almost spherical shape so that it does not become thicker than the basic wall thickness of the lens, the difference in wall thickness of the lens is reduced, which reduces the occurrence of distortion and improves thermal shock resistance. can. Furthermore, when press-molding lenses, the glass flows well in the mold, making the molding easy, and the generation of wrinkles and bubbles can be suppressed. Furthermore, since the lens elements are spaced apart and have a concave shape, there is a convex portion on the mold side, so that the design and manufacturing process of the mold can be performed accurately and easily. 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 enlarged side sectional view of a main part showing a lens for a conventional sealed beam light bulb; FIGS. 2 and 3 are an enlarged side sectional view and front view of a main part showing a lens used in a sealed beam light bulb of the present invention; FIG. 4 is a partially cutaway side view of the sealed beam type light bulb of the present invention. 1... Lens, 13... Lens element.

Claims (1)

[Claims] 1. A lens formed by press molding to form a smooth curved surface on the outer surface and a lens element consisting of a large number of approximately spherical concave portions spaced apart from each other on the inner surface, and a reflecting mirror to which a light source is attached. A sealed beam light bulb characterized by being sealed with and.