JPH06273666A - Lens for projector lamp - Google Patents

Abstract

PURPOSE:To provide the lens for projector lamp which has a satisfactory optical performance and has FNO<=1 to be bright and is superior in productivity and is produced at a low cost and is light-weight. CONSTITUTION:This lens has a convex aspherical shape on the illumination side and has a spherical or aspherical shape on the light source side and is a single plastic lens, where a Fresnel face is formed, and satisfies conditions d/f<0.4 and 0.15<c/d<1 where (d), (f), and (c) are the thickness of the center of the lens, the focal length of the lens, and the inter-face distance at a maximum light height on the axis respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination lens,
In particular, the present invention relates to a lens for a projector lamp, which has excellent optical performance and is very bright with F _NO ≦ 1.

[0002]

2. Description of the Related Art Generally, a lens for a projector lamp is often used for a vehicle headlight and the like, and it is important not only to have optical performance but also to withstand a harsh environment of use and to have high reliability. . Especially when it is used for vehicle headlights, the lens is arranged immediately before the lamp, so that the temperature becomes considerably high. For this reason, single-lens aspherical glass lenses have conventionally been used for projector lamp lenses.

[0003]

However, the single lens aspherical glass lens is usually manufactured by press molding using a mold. Therefore, when manufacturing a lens with a large aperture, there is a problem that the mold life is shortened because the molding cycle is long and the molding temperature is high. That is, in the conventional lens for a projector lamp including a single-lens aspherical glass lens, the initial and running costs are high, and the mass productivity is not good. Further, recently, when a lens for a projector lamp is used particularly for a vehicle headlight, a large-diameter glass lens is not preferable because it is heavy in weight from the viewpoint of reducing the weight of each component.

The present invention has been made in view of such conventional problems, and is a lightweight projector lamp which has good optical performance, is bright with F _NO ≤1, is excellent in productivity, and can be manufactured at low cost. A lens for use is provided.

[0005]

[Means for Solving the Problems] In recent years, many plastic materials with particularly excellent heat resistance have been developed, and plastic lenses can be easily produced by injection molding to produce highly accurate large-diameter aspherical lenses. , If you devise its shape,
The molding cycle can be made very short and it is excellent for mass production.

The present invention focuses on the advantages of this plastic lens, and in order to solve the above-mentioned problems, the illumination side (front side)
Is a convex aspherical shape, and the light source side (rear surface) is spherical or aspherical and has a Fresnel surface. (1) d / f <0.4 (2) 15 <c / d <1, where: d: center thickness of lens f: focal length of lens c: inter-plane distance at maximum axial ray height The lens for projector lamp is configured so as to satisfy the conditions. did.

Here, as a plastic material for forming the lens of the present invention, a material having heat resistance such as PMMA resin or PC resin is most suitable.

[0008]

The above conditions in the present invention will be described below. The conditions (1) and (2) are both conditions in consideration of productivity in manufacturing a plastic lens. The condition (1) is a condition regarding the center thickness of the lens. d
When / f is 0.4 or more, that is, when the center thickness of the lens is large, the moldability is deteriorated, and it becomes difficult to manufacture a highly accurate lens due to the influence of molding shrinkage, and the cost is increased.

The condition (2) is a condition regarding the lens shape (thickness of wall thickness). When c / d becomes 0.15 or less,
That is, when the difference in thickness between the center and the periphery of the lens becomes large, the moldability becomes poor as in the case of the condition (1), and it becomes difficult to manufacture a highly accurate lens due to the influence of molding shrinkage, resulting in high cost. It becomes a factor of. On the other hand, c / d is 1
When it becomes the above, that is, when the curvature on the light source side (rear surface) becomes large, the depth of the Fresnel shape in the optical axis direction becomes deep, and the incident light ray from the light source enters the plane parallel to the optical axis, which deteriorates the performance. In addition, the amount of transmitted light also decreases, which is not preferable.

According to the lens for a projector lamp of the present invention having the above-mentioned structure, the optical performance is good, the brightness is F _NO ≤1, and the Fresnel surface is formed on the spherical or aspherical surface to manufacture the lens. By considering ease of use, the productivity will be excellent and the cost will be low, and since it is a single-lens plastic lens, it will be lightweight even with a large aperture.

[0011]

EXAMPLES Examples of the present invention will be described below. here,
r ₁ and AS 1 are the curvature radius and aspherical surface coefficient on the illumination side (front surface), r ₂ and AS 2 are the curvature radius and aspherical surface coefficient on the light source side (rear surface), r ₃ and AS, respectively.
3 is the radius of curvature and aspherical coefficient of the Fresnel surface formed on the light source side (rear surface) surface, d is the lens center thickness, and n
_d is the refractive index of the lens.

Further, the aspherical shape is expressed by the following equation 1 where C is the paraxial curvature of the vertex, K is the conic constant, and A _i is the aspherical coefficient in an orthogonal coordinate system with the optical axis direction as the X axis. It is a rotationally symmetric aspherical surface.

[0013]

[Equation 1]

As shown in FIG. 11, the Fresnel surface shape is composed of a central zero zone 1 and a continuous edge zone 2 outside thereof, and the continuous edge zone 2 extends between the pitches 3 on the extension of the curved surface of the zero zone 1. A straight line with a slope connecting both ends.

[0015]

Embodiment 1 FIG. 1 is a side view showing a lens for a projector lamp of this embodiment, which lens is made of PMMA resin. FIG. 2 is a spherical aberration diagram of the projector lamp lens of the present embodiment. F _NO = 0.8 f = 100 d / f = 0.12
c / d = 0.65 Fresnel shape (zero zone 0, pitch 0.2) r ₁ = 49.6034 d = 12 n _d =
_{1.49154 r 2 = 50.0000 r 3 =} -4993.0000 AS1 AS2 AS3 K -1 -0.5 0 A 4 0.5969E-06 0 -0.1241E-06 A 6 -0.3962E-10 0 _{-0.2849E-10 A 8 0.1353E-13} 0 0.1949E-14 A 10 0.1416E-18 0 0.5545E-18

[0016]

[Embodiment 2] FIG. 3 is a side view showing a lens for a projector lamp according to this embodiment, which lens is made of PMMA resin. FIG. 4 is a spherical aberration diagram of the projector lamp lens of the present embodiment. F _NO = 0.8 f = 100 d / f = 0.35
c / d = 0.17 Fresnel shape (zero zone 0, pitch _{0.2) r 1 = 49.6530 d =} 35 n d =
_{1.49154 r 2 = 105.0000 r 3 =} -3754.9000 AS1 AS2 AS3 K -1 -0.5 0 A 4 0.5680E-06 0 -0.1176E-06 A 6 -0.4767E-10 0 _{-0.2593E-10 A 8 0.1140E-13} 0 0.2519E-14 A 10 -0.4372E-18 0 0.6348E-18

[0017]

[Embodiment 3] FIG. 5 is a side view showing a lens for a projector lamp according to this embodiment, which lens is made of PC resin. FIG. 6 is a spherical aberration diagram of the projector lamp lens of the present embodiment. F _NO = 1.0 f = 100 d / f = 0.2 c
/D=0.26 Fresnel shape (zero zone 0.5, pitch _{0.5) r 1 = 58.4732 d =} 20 n d =
_{1.58583 r 2 = 150.0000 r 3 =} 27261.0000 AS1 AS2 AS3 K -1 -0.5 0 A 4 0.3334E-06 0 -0.5613E-07 A 6 -0.6171E-10 0 - _{0.2271E-10 A 8 0.1332E-13} 0 0.3299E-14 A 10 0.4713E-18 0 0.1206E-17

[0018]

[Embodiment 4] FIG. 7 is a side view showing a lens for a projector lamp according to this embodiment. This lens is made of PC resin. FIG. 8 is a spherical aberration diagram of the projector lamp lens of the present embodiment. F _NO = 0.9 f = 100 d / f = 0.08
c / d = 0.93 Fresnel shape (zero zone 0, pitch _{0.2) r 1 = 58.5029 d =} 8 n d = 1.
_{58583 r 2 = 63.0000 r 3 =} 40638.0000 AS1 AS3 K -1 0 A 4 0.3897E-06 -0.7127E-07 A 6 -0.5870E-10 -0.2532E-10 A 8 0. _{1256E-13 0.1939E-14 A 10} 0.1227E-18 0.4454E-18

[0019]

[Embodiment 5] FIG. 9 is a side view showing a lens for a projector lamp according to this embodiment, which lens is made of PC resin. FIG. 10 is a spherical aberration diagram of the projector lamp lens of the present embodiment. F _NO = 0.75 f = 100 d / f = 0.28
c / d = 0.25 Fresnel shape (zero zone 1, pitch _{0.3) r 1 = 54.5033 d =} 28 n d =
_{1.58583 r 2 = 80.0000 r 3 =} 634.1200 AS1 AS2 AS3 K -1 -0.5 0 A 4 0.4917E-06 0 -0.1170E-06 A 6 -0.5156E-10 0 - _{0.2766E-10 A 8 0.1086E-13} 0 0.2039E-14 A 10 -0.4546E-18 0 0.4695E-18

[0020]

As described above, according to the projector lamp lens of the present invention, the optical performance is good, and F _NO ≤1.
With a bright and spherical or aspherical surface on which a Fresnel surface is formed, considering ease of manufacturing, it has excellent productivity and low cost. Therefore, it is lightweight even with a large diameter.

[Brief description of drawings]

FIG. 1 is a side view showing a lens for a projector lamp according to a first embodiment of the present invention.

FIG. 2 is a spherical aberration diagram of the lens for projector lamps of Example 1.

FIG. 3 is a side view showing a lens for a projector lamp according to a second embodiment of the present invention.

FIG. 4 is a spherical aberration diagram of the projector lamp lens of the second example.

FIG. 5 is a side view showing a lens for a projector lamp according to a third embodiment of the present invention.

FIG. 6 is a spherical aberration diagram of the projector lamp lens of the third embodiment.

FIG. 7 is a side view showing a lens for a projector lamp according to a fourth embodiment of the present invention.

FIG. 8 is a spherical aberration diagram of the projector lamp lens of the fourth embodiment.

FIG. 9 is a side view showing a lens for projector lamps of Example 5 of the present invention.

FIG. 10 is a spherical aberration diagram of the projector lamp lens of the fifth example.

FIG. 11 is a side view showing a Fresnel surface shape in the present invention.

[Explanation of symbols]

 1 Zero zone 2 Continuous edge zone 3 Pitch

Claims (1)

[Claims] 1. A single-lens plastic lens having a convex aspherical surface on the illumination side and a spherical or aspherical surface on the light source side and forming a Fresnel surface is (1) d / f <0.4 (2) 0.15 <c / d <1, where d: center thickness of lens f: focal length of lens c: inter-plane distance at maximum ray height on axis For projector lamp characterized by lens.