JPH0272504A - Car lighting fixture lens with fresnel lens - Google Patents

Abstract

PURPOSE:To enable engraving the circumferentially continued Fresnel steps by forming Fresnel steps in which radial plotting lines are enlarged ultimately to a minute surface, and twistedly continuing the structural line and structural surface mutually in the joint part of the circumferentially adjacent Fresnel steps. CONSTITUTION:On a lens member 1 consisting of a secondary curved surface having a curvature r1 (not shown in fig) in one direction and a curvature r2 (not shown in fig) in the vertically crossed direction thereto, concentric plotting lines C are concentrically drawn at an equal pitch from the center O of the lens, and a plurality of circular Fresnel step design section 2 are plotted by these lines and a plurality of radial plotting lines R equally divided in the circumferential direction. The circular Fresnel step design section 2 is made minute until a flat lens part 8 is structurally dissolved, and the Fresnel steps 3 are constituted so that the structural line and structural surface of circumferentially adjacent Fresnel steps 3 are mutually continued, and the circumferentially adjacent Fresnel steps 3 are twistedly continued. Hence, Fresnel steps having the circumferentially continued refraction type prism surface and reflecting prism surface can be constituted.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a vehicle lamp having a Fresnel lens in which Fresnel steps consisting of a refractive prism and a reflective prism are formed continuously in the circumferential direction on a non-planar plate. This relates to lenses for use in

[Conventional technology]

Conventionally, a Fresnel step consisting of a refractive prism and a reflective prism formed on the lens plate of a Fresnel lens is generally flat or spherical even if curved, and the lens axis is the optical axis. It is limited to those that form a rotation shape consistent with . In such a structure, each Fresnel step could be easily formed by radial quadratic design.

However, in recent years, lens devices such as outer lenses and inner lenses used in vehicle lights such as automobile taillights and sidemarker lights have been designed with complex curved shapes that follow the outer shape of the vehicle in order to reduce the aerodynamic drag of the outer shape of the vehicle. A vehicle lens has been proposed in which a Fresnel lens is constructed by providing a mosaic of many Fresnel steps on the lens surface of the lens.

[Problem to be solved by the invention]

However, in the structure of the Fresnel lens mentioned above, the Fresnel steps are designed and configured for each design section, so the ridgeline direction of the Fresnel steps with respect to the circumferential direction is different, and the diffusely reflected light at the boundary is noticeable and appears on the lens surface. This has the problem of spoiling the beauty of the Fresnel pattern.

The present invention was devised in view of the above-mentioned problems, and an object of the present invention is to provide a vehicle lamp lens having a Fresnel lens in which continuous Fresnel steps are carved in the circumferential direction on a lens plate material having an arbitrary curved surface. That is.

[Means to solve the problem]

In order to achieve the above object, a lens for a vehicle lamp having a Fresnel lens according to the present invention has the following features: a concentric circular marking line drawn on a lens member forming a plane or a desired curved surface; A radial dividing line passing through the center divides the lens member surface into a large number of arcuate Fresnel step design sections, and in each Fresnel step design section, the transmitted light from the focal point of the lens passes through a refractive prism or a reflective prism. In a prism lens having a refractive prism surface and a reflective prism surface in which the peak angle of each Fresnel step and the slope of the pure white ridge line are designed and shaped so as to emit a substantially parallel beam, the radiation dividing line is ultimately increased. By doing so, a Fresnel step with a microscopic surface is constructed.
Moreover, the gist is to make the structural lines and structural surfaces at the joint portions of circumferentially adjacent Fresnel steps continue in a meandering manner.

[Effect]

The lens for a vehicle lamp having a Fresnel lens according to the present invention has the arcuate Fresnel step design sections individually partitioned as described above arranged in parallel along the partition line in a circular pattern on the lens surface. By ultimately increasing the division line within the designable range and making the Fresnel step design division that makes up the Fresnel step into a microscopic surface, the mountain angle of each Fresnel step and the slope of the white ridgeline can be carved. A Fresnel lens can be constructed in which the resulting refractive prism surface and reflective prism surface have continuous Fresnel steps in the circumferential direction.

〔Example〕

Hereinafter, a specific design principle of engraving Fresnel steps in a lens for a vehicle lamp having a Fresnel lens according to the present invention will be explained.

As shown in Fig. 1, a lens member l consisting of a quadratic curved surface with a curvature rl in one direction and a curvature r2 in a direction perpendicular thereto is placed at equal pitches (pitch width P) from the center O of the lens.
A large number of arc-shaped Fresnel step design sections 2 are created by drawing a circular circular section vAC in the circular shape, and by dividing the concentric circular section line C equally in the circumferential direction passing through the center O. compartmentalize.

FIG. 2 is an enlarged view of one of the arcuate Fresnel step design sections 2, and the arcuate Fresnel step design section 2 has concentric circular section lines CI, C2 and radial section lines R1. , R2. The Fresnel step 3 designed and constructed in the arcuate Fresnel step design section 2 will be explained with reference to FIGS. 3 and 4.

First, as shown in FIG. 3, a ray I11 from a focal point F located on the optical axis of the lens member 1 is transmitted through the center of the Fresnel step 3, and the optical axis is aligned within the radiation section SR. The inclination angle α of the inner slope 4 and the inclination angle β of the outer slope 5 are designed so as to constitute a refraction prism and a reflection prism that are controlled to emit light rays 12 parallel to the Fresnel step. Determine the apex angle γ of 3.

Next, as shown in FIG. 4, while maintaining this apex angle γ, the transmitted light 'l'
The angle of inclination (θ) of the top ridgeline 6 with respect to the lens member 1 is designed so that Al2 is parallel to the optical axis.

At this time, a plane lens portion 8 is designed between the outer valley line 7 formed at the valley position of the outer slope 5 and the concentric circular division line C2.

The above inclination angles α and β are the inclination angles with respect to the orthographic projection line, so the top T is T = α + β, and since α, β and γ are fixed, it is possible to cut it with a 3-axis milling machine. Become.

In the above Fresnel step design method, since each Fresnel step 3 is configured discontinuously on a three-dimensional curved surface, arc-shaped Fresnel step design sections are divided in the radial direction and the circular direction on the lens member surface. In this case, a two-dimensional design can be performed by dividing the light beam in the direction in which it crosses the Fresnel step 3 and in the tangential direction.

The present invention is based on the above engraving design principle, and by increasing the number of radial division lines R to the limit that can be engraved, the arcuate Fresnel step design division 2 is made minute until the flat lens portion 8 is structurally eliminated. In addition, the structural lines and structural surfaces of circumferentially adjacent Fresnel steps 3 are continuous with each other, and the circumferentially adjacent Fresnel steps 3 are configured to meander continuously.

When forming the Fresnel step 3 by engraving based on the engraving design principle of the three-dimensional Fresnel step described above, the Fresnel step 3 of each arcuate Fresnel step design section 2 is
The inclination angle α of the inner slope 4 and the inclination angle β of the outer slope 5
Since the value changes continuously, cutting can be performed by moving a so-called five-axis cutting tool in the circumferential direction while controlling fiL according to the design value, and scanning in the surface direction.

〔Effect of the invention〕

Since the lens for a vehicle lamp having a Fresnel lens according to the present invention is configured as described above, even if the lens member has a curved surface with different curvatures in two directions, the lens structure on the quadratic curve can easily achieve the desired shape. In addition to being able to obtain transmission control light, the structure is continuous in the circumferential direction, reducing diffused reflection of the lens, and the Fresnel steps are continuous in the circumferential direction, making it possible to form a mold. It also has characteristics such as excellent moldability.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a lens member showing a design section of a Fresnel step in a lens for a vehicle lamp having a Fresnel lens according to the present invention (al and an enlarged view showing the shape of a Fresnel step cut into the design section). Perspective view (b
), Figure 2 is an enlarged perspective view showing a three-dimensional Fresnel step, Figure 3 is an explanatory diagram (a) showing the radial design direction of the Fresnel step and its enlarged sectional view (b), and Figure 4 is a circle of the Fresnel step. Explanatory diagram showing the circumferential design direction (al and its enlarged sectional view (b). 1... Lens member 2... Arc-shaped Fresnel step design section 3... Fresnel step 4... Inner slope 5. ...Outer slope 6...Top ridgeline 7...Outer valley line
8... Flat lens part patent applicant Koito Seisakusho Co., Ltd. Agent Patent attorney front 1) Kazuo 1... Lens member 2... Arc-shaped flange design area both 3... Fresnel step 4...・Inner slope 5...Outer slope 6...1r1 part ridgeline 7...Outer valley line 8...Plane lens part 1...Lens member 2...Circular Fresnel Stee, Bu design section 3...・Fresnel step 4...Inner slope 5...Outer slope 6...Top ridge line 7...Outer valley line 8...Plane lens part E...Lens part 4th...Inner slope 5 ...Outside @ slope 6...Top ridgeline 7...Outside valley line 8...'V surface lens part l...Lens member 2...Circular flange design section 3...・Fresnel step 4...Inner slope 5...Outer slope 6...Top ridge line 7...Outer valley line 8...Plane lens part

Claims (1)

[Claims] The lens member surface is divided into a large number of arcuate Fresnel step design sections using concentric circular partition lines drawn on the lens member forming a flat or desired curved surface and radial partition lines passing through the center of the concentric circular partition lines. At the same time, in each Fresnel step design section, the angle of the crest of each Fresnel step and the ridgeline of the ridge are adjusted so that the transmitted light from the focal position of the lens passes through the refractive prism or the reflective prism and exits as a substantially parallel beam. In a Fresnel lens having an inclined refractive prism surface and a reflective prism surface, the radiation division line is ultimately increased to form a Fresnel step that is as small as possible, and adjacent to each other in the circumferential direction. A lens for a vehicle lamp having a Fresnel lens characterized in that structural lines and structural surfaces at joints of Fresnel steps are meandering and continuous.