JPH071685Y2 - Lens for vehicle lamp having elliptical Fresnel lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a processing design technique for forming an elliptical Fresnel step composed of a refraction prism and a reflection prism. The present invention relates to a vehicle lamp lens that constitutes a Fresnel lens (hereinafter referred to as “elliptical Fresnel lens”).

[Conventional technology]

Conventionally, a Fresnel step formed of a refraction-type prism and a reflection-type prism formed on a lens plate material of a Fresnel lens generally forms a concentric circle in its front shape as shown in FIG. Is configured.

However, in recent years, many lenses that form tail lights of automobiles into other vehicle lights have a particularly thin rectangular outer shape for the purpose of reducing aerodynamic resistance of the outer shape of the vehicle body. There is a demand for a lens having a quadric surface having a curved surface (having no axis of rotation). Therefore, conventionally, in the case of a rectangular lens plate material such as a vehicle lamp lens, as shown in FIG. 10, for example, a mold 52 for molding the lattice-shaped prism portion 51 is provided with a core 53 constituting the Fresnel lens portion 50. It was molded using the fitted ones.

[Problems to be solved by the device]

Therefore, in this type of vehicle lamp lens, the molding patterns of the Fresnel lens part 50 and the prism part 51 are generally different, which is subject to design restrictions that result in discontinuity, and due to the core structure. However, there is a problem in that mold cooling is poor and molding defects are likely to occur.

The present invention has been made in view of the above problems, and a Fresnel formed in a three-dimensional direction having different curvatures in two directions and having an elliptical pattern adapted to the plate surface of a rectangular lens plate material. It is an object of the present invention to propose a technique for engraving steps and to provide a vehicle lamp lens having the elliptical Fresnel lens.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a lens for a vehicle lamp having an elliptical Fresnel lens according to the present invention, a concentric elliptical pitch base line is drawn at an appropriate pitch on a lens member surface forming a flat surface or a quadric surface, and In a large number of elliptic arc-shaped Fresnel step design sections intersecting the elliptic pitch baseline with a large number of radiating section lines passing through the center of the elliptical pitch base line, the transmitted light from the back side focal point of the lens incident on each Fresnel step design section So as to form a substantially parallel light beam through a refraction prism or a reflection prism,
The inclination angle of the inner slope of the Fresnel step and the inclination angle of the outer slope are designed to determine the apex angle, and each slope is cut to form Fresnel steps of each chevron, and along the elliptical pitch base line. The gist is that the Fresnel steps of the respective mountain shapes are continuously arranged in parallel.

[Action]

The lens for vehicle lighting equipment having the elliptical Fresnel lens,
Since Fresnel steps are arranged in parallel along the elliptical pitch baseline of the lens surface divided into each Fresnel step design section, an elliptical Fresnel step stripe pattern can be obtained from the front of the lens member, and Fresnel lens and prism In the configuration of the vehicle lighting device lens having a portion, the molding patterns of both processed portions can be formed into an elliptical striped pattern to provide a continuous design.

〔Example〕

Hereinafter, a specific design principle of a Fresnel step in a vehicle lamp lens having an elliptical Fresnel lens according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, for example, a step pattern 3 is engraved on a pattern flat plate 2 as a basic Fresnel lens pattern on a quadric surface such that the rotation axis orthogonal to the surface coincides with the optical axis of the lens. The step pattern 3 is orthographically projected onto a lens member 4 such as a lens cover for a vehicle lighting tool having a quadric surface by aligning the optical axes L with each other. The step pattern 3 is divided into a large number of concentric elliptic pitch base lines C1, C2 ... Having an appropriate pitch drawn with the optical axis L position on the pattern flat plate 2 as the center O, and equally divided in the circumferential direction passing through the center O. .., and the orthographic projection lines are the lines indicated by the symbols C and R on the surface of the lens member 4. The present invention is based on the concentric elliptical pitch baseline C
, C2, and a large number of Fresnel step design sections 1 divided by a large number of radiations R1, R2, ...
The Fresnel step 5 is designed so that the transmitted light from (1) passes through a refraction prism or a reflection prism to form a substantially parallel light flux.

Therefore, when the lens member 4 is a flat plate, the elliptical pitch base line on the pattern flat plate 2 and the radiation form the same pattern by the orthographic projection line projected on the lens member 4.
In this embodiment, a quadric lens member 4 having different curvatures in different directions will be described.

FIG. 2 shows the cross sections of the adjacent radial sections at the positions R1 and R2 of the orthographically projected lens member 4, which are superimposed on each other. The cross section is shown with a subscript 2. Therefore, the lens member is also indicated as 41 or 42.

The structure of the adjacent Fresnel step 5 between the elliptical pitch base lines C1 and C2 will be described with reference to FIGS. 3 and 4. Rays 1 and l2 from the focal point F on the optical axis L of the lens member 4
However, each of the Fresnel step design sections 1 is configured so as to form a refraction system prism and a reflection system prism that obtain light rays l′ 1 and l′ 2 parallel to the optical axis L via the end of the Fresnel step 5. Inclination angles α1 and α2 at both ends of the inner slope 6
Then, the inclination angles β1 and β2 at both ends of the outer slope 7 are designed to determine the apex angles γ1 and γ2 at both ends of each Fresnel step 5.

Since the inclination angles α1, α2 and β1, β2 are inclination angles with respect to the orthographic projection line, the respective apex angles γ1, γ2 are γ1 = α1 + β1 γ2 = α2 + β2, respectively.

Therefore, the tilt angle change amount α1 → α2 and β1
→ β2, and the variable is each Fresnel step design section 1
During Fresnel step cutting, the angle of the cutting tool can be changed by a milling machine or the cutting position can be gradually changed to start cutting. Since the Fresnel steps 5 thus formed are continuously arranged in parallel along the elliptical pitch base line C, the entire Fresnel step fringes form an elliptical Fresnel step fringe.

Next, FIGS. 5 and 6 show the structure of the Fresnel step 5 having another structure. The Fresnel step 5 configured in each Fresnel step design section 1 first has the structure shown in FIG. As shown in (b), the lens member 4
Refraction prism for controlling the light ray 1 from the focal point F on the optical axis L to pass through the central portion of the Fresnel step 5 and become a light ray l2 parallel to the optical axis L in the radiation section SR. In order to construct a reflection prism, the inclination angle α of the inner slope 6 and the inclination angle β of the outer slope 7 are designed to determine the apex angle γ of the Fresnel step 5.

Next, as shown in FIGS. 8A and 8B, this apex angle γ
The lens member 4 is arranged so that the transmitted ray 12 is parallel to the optical axis L in the tangential plane SC in the elliptic pitch base line C direction while maintaining
The inclination angle θ of the top twill line 8 with respect to is configured.

At this time, the flat lens portion 10 is formed between the outer valley line 9 formed at the valley position of the outer slope 7 and the elliptical pitch base line C2.

Since the tilt angles α and β are tilt angles with respect to the orthographic projection line, the apex angle γ is γ = α + β, and α, β and γ are fixed.

Since the Fresnel steps 5 thus formed are juxtaposed along the elliptical pitch base line C, the entire Fresnel steps 5 form an elliptical Fresnel step fringe.

[Effect of device]

Since the lens for vehicle lighting equipment having the elliptical Fresnel lens according to the present invention is configured as described above, the Fresnel steps are arranged in parallel along the elliptical pitch base line of the lens surface divided into each Fresnel step setting section. , An elliptical Fresnel step stripe pattern can be obtained from the front surface of the lens member, and when forming a lens for vehicle lighting equipment having a Fresnel lens portion and a prism portion, the molding patterns of both processed portions are continuously formed into an elliptical stripe pattern. It can be a design.

Further, even if the lens member is a curved surface having different curvatures in two directions, it is possible to easily cut the Fresnel step having a three-dimensional structure by the milling machine, so that it is possible to reduce the processing cost of the vehicle lamp lens. Therefore, the practical effect after implementing the present invention is extremely large.

[Brief description of drawings]

1 and 2 are explanatory views showing the principle of a lens for vehicle lighting equipment having an elliptical Fresnel lens according to the present invention, and FIG. 3 is a lens member showing a first design example of a Fresnel step having a three-dimensional structure. Partially cutaway front enlarged view, FIG. 4 is an enlarged perspective view showing the Fresnel step, and FIG. 5 is a partially cutaway front enlarged view of a lens member showing a Fresnel step having another three-dimensional structure. FIG. 7 is an enlarged perspective view showing the Fresnel step, FIG. 7 shows a second design example of the Fresnel step having a three-dimensional structure, (a) is an explanatory view, (b) is a sectional view of a main part, FIG. 8 shows a second design example of a Fresnel step having the same three-dimensional structure. (A) is an explanatory view, (b) is a sectional view of a main part, and FIG. 9 is a conventional circular core circular Fresnel step structure. Front view of a lens for vehicle lighting equipment having FIG. 10 is a sectional view of an essential part of the molding die. 1 ... Fresnel step design section 3 ... Step pattern, 4 ... Lens member 5 ... Fresnel step, 6 ... Inner slope 7 ... Outside slope, 8 ... Twill line 9 ... Outside valley line, 10 ... Flat lens part

Claims (1)

[Scope of utility model registration request] 1. A concentric elliptical pitch base line is drawn at an appropriate pitch on a surface of a lens member forming a flat surface or a quadric surface, and the elliptical pitch base line is formed by a large number of radial division lines passing through the center of the elliptic pitch base line. In each of a number of elliptic arc-shaped Fresnel step design sections that are cross-sectioned, each of the Fresnel step design sections is configured so that the transmitted light from the back side focal point of the lens exits a substantially parallel light flux through a refraction prism or a reflection prism. In addition, the inclination angle of the inner slope of the Fresnel step and the inclination angle of the outer slope are designed to determine the apex angle, and each slope is cut to form each Fresnel step of each chevron. A lens for a vehicle lighting device having an elliptical Fresnel lens, characterized in that Fresnel steps of the respective mountain shapes are continuously arranged in parallel.