JP2008226542A - Projection lens for projector-type headlight - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a conventional projector-type headlight uses a glass plano-convex lens as a projection lens, which cannot avoid generating chromatic aberrations giving rise to coloring felt around light and darkness boundaries. <P>SOLUTION: A light source is to be an LED to lower its calorific value, and the projection lens is made to withstand the heat radiation from the light source, even with an achromatic lens (achromat), formed of transparent resin of high refraction and high dispersion and transparent resin of low refraction and low dispersion, so that coloring will not occur even under light distribution characteristics, for instance, at a part such as lightness and darkness boundary lines where coloring is easily felt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a headlight, and more specifically, is called a projector-type headlight, and is a second-focused light on which an image of a light source placed at the first focal point of a reflecting surface having a spheroidal surface is formed. A head that has a light-shielding plate through which light having a desired light distribution characteristic passes is installed in the vicinity, and is enlarged and projected in the irradiation direction by a projection lens in which the shape of the light that has passed through the light-shielding plate is aspheric. This relates to the configuration of the projection lens of the light.

  FIG. 9 shows an example of the configuration of a conventional projector-type headlight 90 of this type, and a light-emitting metal ellipsoid 91 having a power consumption of about 40 W is adopted as a light source, and a spheroid surface rotated on the long axis side. A light emission source 91 a such as an arc is disposed at the position of the first focal point of the reflecting mirror 92.

  By doing so, the light from the light source 91a arranged at the first focal point converges at the position of the second focal point of the spheroid reflecting mirror 92, so that it is in the vicinity of the second focal point. A shade 93 that shields the light reflected by the lower half of the spheroid reflector 92 is provided, and only the light reflected by the upper half of the spheroid reflector 92 is allowed to pass. (However, in this headlight 90, the shade 93 is movable so that the light distribution characteristics can be switched.)

  Therefore, the light beam after passing through the shade 93 has a semicircular cross section in the lower chord, and is enlarged and projected in the irradiation direction by the projection lens 94 with the irradiation direction vertically and horizontally reversed. . Therefore, the irradiation light as the projector-type headlight 90 does not include any upward light, and can prevent the driver of the oncoming vehicle from being dazzled. Since the projection lens 94 generates a large amount of heat from the metal halide discharge lamp 91, an aspheric lens obtained by molding glass with a press is used in consideration of heat resistance.

  However, in recent years, the performance of LEDs has been improved, and it has become possible to realize a high-brightness lamp with low power consumption. Therefore, as shown in FIG. It is out.

In this case as well, basically, the light reflected by the upper half of the spheroid reflecting mirror 82 is selectively passed through the shade 83 to form a light distribution, and the projection lens 84 expands and reverses the irradiation direction. This is the same in that the light is projected and the light distribution as the headlight 80 is obtained. However, when the light source is the LED 81, it is easy to radiate light mainly in the direction of the upper half, so that the spheroid reflecting mirror 82 only needs to be substantially upper half, so that heat dissipation becomes easier. There are also benefits. In the figure, reference numerals 86 and 87 denote auxiliary reflectors.
JP 2002-056708 A JP 2005-276805 A

  However, in the above-described conventional projector-type headlights 80 and 90, the projection lenses 84 and 94 are formed in a convex lens shape with glass as a single material in order to cope with heat generated from the light source. Therefore, when the light emitted from one point of the second focal point is projected, there arises a problem that on the light distribution pattern, a chromatic aberration of the convex lens causes a portion that is colored more than that defined in the light distribution standard. It was.

  In order to solve this problem, conventionally, shades 83 and 93 have been increased in thickness. That is, by increasing the thickness of the shades 83 and 93, the light reflected at the respective positions before and after the thickness surface is transmitted through the portions in the projection lenses 84 and 94 while being mixed. They were mixed to prevent specific color development.

  However, by doing so, a specific color is not generated in the irradiated light, but the thickness of the shades 83 and 93 should be increased so that the projection lenses 84 and 94 should be originally reached. Light is blocked by the thickness of the shades 83 and 93. Or the phenomenon that the ratio of the light reflected in the direction shifted | deviated from the direction aimed at irradiation also arises, and the problem that the light quantity which should become effective was not a little lost also had arisen.

  The present invention has been made in view of the above-described conventional problems. Since the light source is changed to the LED, the heat resistance required for the projection lens can be reduced. A projection lens for a projector-type headlight as a light source, wherein the projection lens includes a biconvex lens employing a low refraction / low dispersion resin member and a meniscus lens employing a high refraction / high dispersion resin member. By providing a projection lens for projector-type headlights, which is a projection lens formed by two-color molding or insert molding, it is possible to color the light distribution characteristics as an achromatic lens (achromat). It solves the problem as something that does not cause spoilage.

  According to the present invention, by using two types of transparent resin members having different refractive indexes and dispersion ratios, a projection lens that is a combination of a biconvex lens and a meniscus lens is formed by two-color molding or insert molding. By superimposing the complementary colors red light and blue light and achromatizing, it is possible to realize a projector-type headlight that does not cause coloring in the light distribution characteristics, and it is excellent in improving the quality of this type of headlight There is an effect.

  Below, this invention is demonstrated in detail based on embodiment shown in a figure. 1 is a projection lens for a projector-type headlight according to the present invention. As described above, the projection lens 1 has an LED as a light source, and the projection lens 1 has low heat resistance. Since it has become possible, a colorless and transparent resin member is selected as a material for forming the projection lens 1.

  At the same time, using two types of resin members with different refractive indexes and dispersion ratios, the two lenses 1A and 1B are bonded to each other, and by devising the shape of each lens, a so-called achromatic lens (achromat) = Two-color achromatic), so that the light distribution characteristic is not colored even when the thin shade 2 is used.

  Here, when the configuration of the projection lens 1 is described in more detail, the projection lens 1 is configured by combining two lenses as described above. In this embodiment, the projection lens 1 is a combination of the two lenses. 1 is, for example, a biconvex lens 1A having a convex surface on both sides formed of a resin member having a refractive index (1.49) and dispersion (Abbe number 58), such as methacrylic resin, and a higher refractive index than the biconvex lens 1A ( 1.58), which is formed by a combination of meniscus lenses 1B having one surface formed of, for example, polycarbonate resin which is a dispersion (Abbe number 31) being a convex surface and the other surface being a concave surface.

  At this time, the bonding surface H of the concave surface side of the meniscus lens 1B formed of a resin member having a high refractive index and the biconvex lens 1A formed of a resin member having a lower refractive index than that of the lens 1A, 1B is formed as a spherical surface having the same curvature, and in this embodiment, as described in the formation method described later, the air layer is completely in close contact with the air layer.

  In carrying out the present invention, as described above, the biconvex lens 1A is not limited to methacrylic resin and the meniscus lens 1B is not limited to polycarbonate resin, and the meniscus lens 1B side is formed of cycloolefin resin. As a general trend, the larger the difference in the refractive index between the two lenses 1A and 1B, the higher the achromatic effect, and according to the results of trial production by the inventor, the combination of methacrylic resin and polycarbonate resin is optimal. Results were obtained.

  2 and 3 show an example of a process for forming the lens 1 described above. First, a mold 20 for forming the meniscus lens 1B is prepared, and a polycarbonate is formed in the mold 20. Resin is injected by means such as injection molding, and the meniscus lens 1B is formed in the mold 20.

  At this time, the mold 20 for forming the meniscus lens 1B can be divided into a front half part 20a that forms a convex part and a part that forms a concave part 20b. When the molding of the meniscus lens 1B is completed, the latter half 20b is removed.

  As shown in FIG. 3, instead of the mold of the latter half portion 20b, the second latter half portion 20c, which is a die formed with the convex surface of the rear surface of the biconvex lens 1A, is formed in the previous step. It is attached to a mold 20a that holds the meniscus lens 1B. Therefore, a gap having the same shape as that of the biconvex lens 1A exists in the inside where the front half 20a and the second half 20c are combined.

  Therefore, if methacrylic resin is injected into the gap of the second rear half 20c, the methacrylic resin is filled into the gap having the same shape as the biconvex lens 1A, and the biconvex lens 1A is formed by a so-called two-color molding method. At this time, since the meniscus lens 1B is in close contact with the mold 20a at the time of the previous molding, the lenses 1A and 1B are completely connected without including an air layer or bubbles between them. It will be formed closely.

  In the above manufacturing process, for example, a flange 1C for mounting the projection lens 1 is also formed at the same time. Further, for example, the meniscus lens 1B (or the convex lens 1A may be used) is formed in advance by another mold (not shown), and the first half 20a and the second second half 20c of the mold 20 described above are formed. Of a so-called insert mold, in which a meniscus lens 1B is fitted into a portion corresponding to the front half portion 20a of a mold having a shape combined with a pair, and methacrylic resin is injected into a space corresponding to the biconvex lens 1A. It may be formed by a method.

  As shown in FIG. 4, the flange 1C for attaching the projection lens 1 to the lens holder 3 of the lamp 10 and the like at the same time is projected, for example, by using the manufacturing process of the both lenses 1A and 1B described above. The lens 1 can be provided at the periphery of the lens 1 and is preferable from the viewpoint of reducing the number of man-hours.

  Here, the advantage of forming the biconvex lens 1A and the meniscus lens 1B in close contact with each other as described above will be described as an achromatic effect even if there is a gap between the opposing surfaces of the two lenses 1A and 1B. It is said that almost the same action and effect can be obtained. However, since it is said that the transmission efficiency as a lens decreases as the number of contact surfaces with the atmosphere orthogonal to the light traveling direction increases, the two lenses 1A and 1B are interposed between the two lenses 1A and 1B as in the present invention. Adhering so as not to include the layer is advantageous from the viewpoint of improving the transmittance.

  4 to 6 utilize the fact that the projection lens 1 is made of resin according to the present invention, so that partial microfabrication by a mold or the like is facilitated, for example, the projection lens 1 and the lens. 4 is an example in which a light transmitting portion 1D for decoration or special light distribution in which the front and back surfaces are parallel is provided between the outer circumferences of the flange 1C supported by the holder 3, and the projection lens shown in FIG. The translucent part 1D is provided between the effective part E as 1 and being supported by the lens holder 3, and the translucent part 1D is provided with, for example, a knurled cut 4 having a radial shape, a concentric shape or the like. Is.

  In this manner, when the light source is turned on, the knurled cut 4 shines in a ring shape, and various decorative effects that were impossible with a glass projection lens can be easily obtained. Since the cut 4 may be formed in the mold 20a, the cut 4 can be carried out without causing any special cost increase.

  FIG. 5 shows an example in which the light transmission part 1D is used to obtain a light distribution for reading, for example, a guide sign installed across an expressway. And a portion supported by the lens holder 3 and a part such as the upper side is provided with a translucent portion 1E that makes light go straight or refracts upward appropriately.

  As shown in FIG. 6, the reflecting mirror 11 of the vehicular lamp 10 to which the projection lens 1 provided with the translucent part 1E shown in FIG. 5 is attached is positioned at a position corresponding to the translucent part 1D. Is provided with a small reflection surface 11a that reflects light from the light source 12 upward, and the light from the reflection surface 11a is emitted to the outside through the light projecting unit 1D.

  FIG. 7 shows an example of the light distribution characteristic of the lamp formed in this way, and a normal light distribution characteristic HL is projected from the horizontal line to the lower half, and the oncoming vehicle is not dazzled. On the upper side, a light distribution characteristic HH for label reading appears.

  FIG. 8 shows the appearance of the lamp 10 formed according to the present invention, which has the same shape as a projector-type headlight that has been used in the past, and the projection lens 1 is made of a transparent resin. There is no sense of discomfort for the viewer.

It is sectional drawing which shows the structure of the projection lens which concerns on this invention. It is explanatory drawing which similarly shows the 1st process of the formation method of the projection lens which concerns on this invention. It is explanatory drawing which similarly shows the 2nd process of the formation method of a projection lens. It is explanatory drawing which shows another embodiment of the projection lens which concerns on this invention. It is explanatory drawing which shows another embodiment of the projection lens which concerns on this invention. It is sectional drawing which shows the example of a structure of the lamp | ramp which employ | adopted the projection lens by another embodiment. It is explanatory drawing which shows the example of the light distribution characteristic by the projection lens obtained by another embodiment. It is a perspective view which shows the external appearance of the headlamp which employ | adopted the projection lens of this invention. It is explanatory drawing which shows the example of the projection lens which uses the conventional discharge lamp as a light source. It is explanatory drawing which shows the example of the projection lens which uses the conventional LED as a light source.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Projection lens 1A ... Biconvex lens 1B ... Meniscus lens 1C ... Flange 1D, 1E ... Translucent part 2 ... Shade 3 ... Lens holder 4 ... Knurled cut 10 ... Lamp 11 ... Reflective surface 11a ... Small reflective surface 20 ... Mold 20a ... first half 20b ... second half 20c ... second half

Claims (4)

  A projection lens for a projector-type headlight using an LED as a light source, wherein the projection lens is a biconvex lens employing a low refraction / low dispersion resin member and a meniscus lens employing a high refraction / high dispersion resin member. A projection lens for a projector-type headlight, wherein the projection lens is formed by two-color molding or insert molding.   The outer diameter portion of the projection lens is provided with a flange portion having a function of attaching the projection lens to the projector type headlight and an optical function other than the projection lens. Item 5. A projection lens for a projector-type headlight according to Item 1.   The resin member employed for forming the projection lens is a combination of any one of polycarbonate resin, methacrylic resin, cycloolefin resin, and polystyrene resin that is transparent and thermoplastic. A projection lens for a projector-type headlight according to claim 1 or 2.   The projection lens for a projector type headlight according to any one of claims 1 to 3, wherein the biconvex lens is a methacrylic resin, and the meniscus lens is a polycarbonate resin.

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