JPH0139363Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a lens for a vehicle lamp.

In order to diffuse the irradiated light beam, the lens of the vehicle lamp has a convex fisheye cut b on the inner surface of the lens a as shown in Fig. 1A, or a concave fisheye cut as shown in B. c is often applied.
In this case, P is the pitch of the fisheye cut, R is the radius of curvature of the fisheye cut, and α is the diffusion angle.In the case of an automobile lamp, the vertical direction is The angle is approximately 10 degrees, and the horizontal direction is approximately 20 degrees. For this reason, the radius of curvature R of the fisheye cut often differs between the top and bottom, left and right sides, and it is necessary to process the fisheye cut using a special cutter.

According to such a conventional fisheye cut, the pitch P of the fisheye cut is changed in order to obtain a roughness when lighting.
Increasing the lens a also increases the thickness of the lens a, and increasing the pitch also increases the weight of the lens a. Furthermore, processing and polishing fisheye cuts takes a long time and is inefficient.
Making the mold was also difficult.

The object of the present invention is to provide a lens for a vehicle lamp that is thinner and lighter and can be easily produced, thereby overcoming the conventional disadvantages.

The gist of the configuration of the present invention that achieves this objective is that the front face is polygonal and a large number of extremely small Fresnel lenses with a lens cut pitch of 0.3 mm or less are assembled vertically and horizontally without gaps.

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments. In general, the resolving power of human vision is approximately 40 to 60" in visual angle, and the distance d at which the ring-shaped pattern of the Fresnel cut can be felt and the pitch P of the Fresnel cut is d = P / tan 40 to 60". =3438P~5155P...(1) The following relational expression holds true, and the distance for evaluating the external design of a lamp is usually around 1 mm, so
In this invention, the cut of the lens is not noticeable when viewed from this distance, and in order to improve the appearance, the above relational expression (1) is used.
Therefore, the pitch P is set to 0.3 mm or less. 1 is a lens element with a rectangular front surface and a convex Fresnel cut 1a with a pitch of 0.3 mm or less and a focal length F on the outer surface (the surface opposite to the light source), and a large number of these lens elements are assembled vertically and horizontally. The lens 2 is configured in such a shape. The following relational expressions hold between the external dimensions A and B of the lens element 1, the diffusion angles α _A and α _B , and the focal length F: A=2F・tanα _A B=2F・tanα _B (2) In the figure, C indicates the center of each Fresnel cut 1a.

FIG. 2B shows an embodiment in which the lens element 1' has a hexagonal shape when viewed from the front. In this case, as in the lens element 1, a convex Fresnel cut with a pitch of 0.3 mm or less and a focal length F is cut on the outer surface. and by setting the dimensions to A and B, the above relational expression (2) can be obtained.
It is possible to form a lens 2' that satisfies the following.

In addition, FIG. 6 shows a very small Fresnel cut 11 similar to that described above on the inner surface (surface on the light source side) of the lens element 11.
An example in which a is applied is shown, and the diffusion angle α is
The irradiation light can be diffused by using

Furthermore, FIG. 7 shows an embodiment in which the extremely small Fresnel cut 21a formed on the lens element 21 is concave, and in this case also, the light can be diffused at the diffusion angle α.

In addition, a mold (referred to as a pin) in which an extremely small pitch Fresnel lens cut of the lens element is formed on the tip surface.
A mold can be easily manufactured by preparing a large number of molds and bundling them together when molding a lens. In this way, the mold (pin) is treated as a standard product and can be used again.

To mold lenses using the press method, a large number of electroformed products are made using the mold (pin) as a master.
Next, a mold (stamper) for molding is formed by electroforming using the master material that connects these parts into a lens shape, and by compressing the plastic sheet material with this mold, the desired lens can be made.

As explained above, the lens of the present invention has a polygonal front face and a large number of extremely small Fresnel lenses with a lens cut pitch of 0.3 mm or less, so the lens thickness can be reduced, and the basic It may be in the form of a film with a wall thickness of 1 mm or less, and it is possible to reduce the weight of the lens. Furthermore, it is convenient if a large number of basic lens element molds are made in advance so that a mold for molding the lens can be easily manufactured by combining them when necessary. In the case of conventional fisheye cuts, the mold polishing process took a long time, but by converting the fisheye cut into an extremely small Fresnel cut, the mold polishing process is no longer necessary. In addition, since the refraction angle can be freely set for each step of the ultra-small Fresnel cut, it is possible to cut not only convex lenses but also concave lenses, which increases the degree of design freedom and improves the lighting feeling and light distribution performance of the lamp. I'm raising it. Furthermore, since the pitch of the Fresnel lens is 0.3 mm or less, the cut is not conspicuous, and the appearance of the lens is similar to that of a conventional fisheye cut.

[Brief explanation of the drawing]

Figure 1 A and B are both explanatory diagrams of the conventional example, and Figure 2
Figures A and B are both front views of the lens according to the present invention, Figure 3 is a front view of the lens element, and Figure 4 is the front view of the lens element.
5 is a sectional view taken along the Y-Y line, FIG. 6 is a sectional view of a lens showing an embodiment in which a lens cut is formed on the inner surface, and FIG. 7 is a sectional view taken along the line Y-Y. FIG. 1... Lens element, 1a... Fresnel cut,
2...Lens.

Claims (1)

[Scope of utility model registration request] The front face is polygonal and the lens cut pitch is 0.3mm.
A lens for a vehicle lamp characterized by having a shape in which a large number of the following extremely small Fresnel lenses are assembled vertically and horizontally without gaps.