JP2015032439A - Vehicle headlight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle headlight capable of achieving distribution of chromaticity of emitted light sufficiently within a standard white chromaticity range.SOLUTION: A vehicle headlight includes: a white light source that includes a semiconductor light-emitting element and a phosphor; and an optical system that includes a reflector radiating light emitted from the white light source forward. The reflector includes an absorption film on a reflection surface, and the absorption film has optical characteristics that chromaticity of light transmitted by standard light A satisfies 0.4≤x and 0.1≤y≤0.4 on chromaticity coordinates (CIE1931). The absorption film shifts the chromaticity of the light emitted from the white light source to reddish side.

Description

  The present invention relates to a vehicular headlamp including a reflector, and more particularly to a vehicular headlamp using a white light-emitting light source including a phosphor as a light source.

  Patent Document 1 discloses a vehicular lamp using a white light emitting device including a semiconductor light emitting element and a phosphor.

JP 2011-108672 A

  In a vehicular lamp using a white light emitting device including a phosphor as in Patent Document 1, a chromaticity distribution exists in the light distribution. This chromaticity distribution is mainly due to an optical path difference in which excitation light passes through the phosphor region in the white light emitting device. The light distribution of the vehicle headlamp is required to satisfy the white range on the CIE chromaticity diagram stipulated by laws and regulations, and the chromaticity distribution of the white light emitting device as the light source is also within this white range. It was designed to fit.

  However, if the chromaticity distribution of the white light emitting device does not have a margin with respect to the white range specified by the regulations, the chromaticity distribution of the light distribution of the vehicle headlamp also has a margin with respect to the white range specified by the regulations. There wasn't.

  Further, due to manufacturing variations of white light emitting devices, a chromaticity distribution is also generated in the light emission of each white light emitting device. Therefore, the white range on the CIE chromaticity diagram in which the chromaticity of the light distribution of the vehicle headlamp is regulated by law. The problem was difficult to meet.

  Therefore, it has been necessary to use a white light emitting device in a predetermined chromaticity range with a margin in the range stipulated by laws and regulations as a light source. In other words, the chromaticity range of a white light emitting device that can be used as a light source is limited, and there is a need for a strict selection of only white light emitting devices that are used as a light source within a predetermined chromaticity range. It was.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicular headlamp that solves the above-described problems and that can easily satisfy the white range on the CIE chromaticity diagram in which the chromaticity of the light distribution is stipulated by law. To do.

  The vehicle headlamp of the present invention includes a white light source including a semiconductor light emitting element and a phosphor, and an optical system including a reflector that emits light emitted from the white light source to the front of the vehicle with a predetermined light distribution, The reflector includes an absorption film on a reflection surface. The absorption film has optical characteristics such that the chromaticity of the light transmitted through the standard light A is 0.4 ≦ x and 0.1 ≦ y ≦ 0.4 on the chromaticity coordinates (CIE1931). In particular, the light absorbing film has optical characteristics such that the chromaticity of light transmitted through the standard light A is 0.4 <x <0.55 and 0.25 <y <0.35 on the chromaticity coordinates (CIE1931). It is preferable to have.

  Moreover, in a reflector provided with a top coat on the reflection film, the absorption film can be constituted by containing a dye that absorbs light of a predetermined wavelength in the top coat.

  According to the vehicle headlamp of the present invention, the chromaticity of the light distribution can easily satisfy the white range on the CIE chromaticity diagram defined by the law. And the chromaticity range of the white light source which can be used as a light source can be made wide compared with the conventional vehicle headlamp.

It is a figure which shows the principal part of the vehicle headlamp of the Example of this invention. (A) It is a schematic sectional drawing of the principal part of the white light source in the vehicle headlamp of the Example of this invention. (B) It is a schematic sectional drawing of a part of reflector in the vehicle headlamp of the Example of this invention. (A) It is a schematic diagram of the white light source explaining the chromaticity distribution in the white light source in the vehicle headlamp of the Example of this invention. (B) It is a figure explaining chromaticity distribution in the light distribution pattern of the vehicle headlamp of the Example of this invention. It is a figure explaining the chromaticity distribution in the white light source in the vehicle headlamp of the Example of this invention. It is a figure explaining the chromaticity distribution in the light distribution of the vehicle headlamp of the Example of this invention. (A) It is a figure explaining the modification of the reflector in the vehicle headlamp of this invention. (B) It is a figure explaining the modification of the white light source in the vehicle headlamp of this invention. It is a figure explaining the chromaticity distribution in the light distribution of the vehicle headlamp of the comparative example of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. As long as there is no description, it is not restricted to these embodiments.

  Hereinafter, a vehicle headlamp according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of a vehicle headlamp 10 according to an embodiment of the present invention.
This vehicle headlamp 10 includes a plurality of white light sources 1 and an optical system including a reflector 2 and is used as a fog lamp.

  As shown in FIG. 2A, one white light source 1 includes a semiconductor light emitting element 3 and a layer 4 containing a phosphor. For example, a blue LED chip having an emission peak wavelength of 430 nm to 490 nm and a yellow phosphor having an emission peak wavelength of 550 nm to 600 nm can be used.

  In particular, an InGaN-based blue LED chip having a peak wavelength of light emission with a high emission efficiency of 470 nm to 475 nm, and a YAG having an excitation light rate due to light emission from the blue LED chip and a peak wavelength of light emission with a high emission efficiency of 555 nm to 575 nm. Phosphors such as phosphors and silicate phosphors can be suitably used. According to this white light source, the coordinate values (x, y) on the chromaticity coordinates (CIE1931) are (0.30, 0.28), (0.40, 0.39), (0.40, 0). .41) and (0.30, 0.36), white light emission in a chromaticity range surrounded by a straight line can be obtained.

  In this embodiment, the white light source is composed of a blue light emitting InGaN LED chip and a yellow light emitting YAG phosphor.

  As shown in FIG. 2B, the reflector 2 is configured by sequentially laminating a reflective film 6 and a color topcoat (absorbing film) 7 on a molded resin substrate 5. The reflective film 6 is made of a highly reflective metal film such as Al or Ag, and forms a reflective surface. The reflector 2 irradiates the front of the vehicle with the radiated light from the white light source on its reflecting surface. The reflector 2 that forms the optical system has a reflecting surface that forms a paraboloid, and the focal line thereof is arranged so as to substantially coincide with the line shape in which a plurality of white light sources are arranged.

  The color top coat (absorbing film) 7 is made of a resin containing a dye that absorbs light of a predetermined wavelength, and protects the reflecting film 6 with a function of absorbing part of the emitted light from the white light source 1. It has the function to do. The color top coat 7 has a chromaticity of light transmitted through the standard light A (light from the standard light source A) of 0.4 ≦ x and 0.1 ≦ y ≦ 0.4 on the chromaticity coordinates (CIE1931). It has the following optical characteristics and is reddish. In particular, the color top coat has optical characteristics such that the chromaticity of the light transmitted through the standard light A is 0.4 <x <0.55 and 0.25 <y <0.35 on the chromaticity coordinates (CIE1931). It is preferable to have. The standard light A has a color temperature of 2856K and has a spectral distribution of a general incandescent lamp. The chromaticity of the standard light A is x = 0.476, y = 0.0 on the chromaticity coordinates (CIE1931). 4074.

  As shown to Fig.3 (a), the one white light source 1 is comprised so that the light emission from LED chip 3 may pass the layer 4 containing a fluorescent substance, the blue light from an LED chip, and an LED chip White light emission is obtained by mixed light with yellow light obtained by converting a part of the light emission from the phosphor. The light emitted from the white light source has a difference in white color due to an optical path difference passing through the layer containing the phosphor. Of the three light beams from the LED chip shown in FIG. 3A, the light beam L1 traveling directly above the central LED chip passes through the layer containing the phosphor as compared with the other light beams L2 and L3. Since the optical path is short, the emission color is blue. The chromaticity of the emitted light from the white light source is distributed on a line segment connecting the chromaticity of the LED chip and the luminescence of the phosphor on the chromaticity coordinates.

  As shown in FIG. 3 (b), the irradiation light of the fog lamp 10 of this embodiment forms a light distribution pattern of the fog lamp on the virtual screen in front of the vehicle. This light distribution pattern satisfies the fog lamp orientation standard, the light irradiation range is below the horizontal reference line HH line, and there is a light-dark boundary line (cut-off line) in the vicinity of the HH line. It is formed. Also in the light distribution pattern, a chromaticity distribution is generated due to the chromaticity distribution of the emitted light from the white light source. For example, the chromaticity of light on the cut-off line (the chromaticity of the portion indicated by the point A in FIG. 3B) and the chromaticity of the high light intensity region at the center of the light distribution pattern (at the point B in FIG. 3B). The chromaticity of the light on the cut-off line is yellow.

  FIG. 4 shows the chromaticity distribution of the emitted light from one white light source 1 used in this embodiment on the chromaticity coordinates (CIE1931). The chromaticity was observed with the viewing angle of the white light source 1 changed by 10 degrees. The chromaticity of the light emitted from the white light source is x = 0.313 and y = 0.313 (shown as black circles in FIG. 4) closer to blue on the chromaticity coordinates, and x = 0.337, y closer to yellow. = 0.357 (indicated by black circles in FIG. 4).

  In FIG. 4, the white range R defined by the ECE rule (ECE48) is indicated by a solid line. The light distribution of the vehicle headlamp is required to satisfy the white range R defined by this rule. The white range R has (0.310, 0.283), (0.443, 0.382), (0.500, 0.382), (0.500, 0.440), (0.453, 0.440), and (0.310, 0.348).

  Further, in FIG. 4, a white range S preferable for satisfying the light distribution of the vehicle headlamp with a chromaticity margin with respect to the white range R is indicated by a dotted line. This white range S has (0.315, 0.292), (0.370, 0.333), (0.370, 0.382), (0.315, 0.346) is a range surrounded by a straight line. That is, it is preferable that the chromaticity distribution in the light distribution of the vehicle headlamp falls within the white range S. The white range S is a range in which both the x value and the y value are within 0.005 with respect to the boundary line defining the white range R on the chromaticity coordinates, and the x value is 0.370. The range is as follows.

  The chromaticity of the emitted light from the white light source of this embodiment is distributed within the white range R defined by the ECE rule (ECE48). However, the blue side ends (0.313, 0.313) in the chromaticity distribution of the emitted light do not satisfy the optimum white range S.

  FIG. 5 shows the chromaticity distribution in the light distribution pattern of the fog lamp 10 of this embodiment and the chromaticity distribution of the white light source 1 shown in FIG. Since the chromaticity distribution in the light distribution pattern of the fog lamp 10 appears on the reference line V in the vertical direction, the measurement results of 8 points (including both ends and the center) on the V line are plotted in FIG. The light emitted from the fog lamp 10 is emitted from the white light source 1 after passing through the color top coat 7. That is, a part of the light emitted from the white light source 1 having a predetermined wavelength is emitted from the color top coat 7. Is absorbed by. In this embodiment, on the chromaticity coordinate, x = 0.330 and y = 0.313 on the blue side (indicated by black circles in FIG. 5) to x = 0.362 and y = 0.358 on the yellow side. It is distributed on a straight line until it is displayed by a black circle in FIG. That is, the chromaticity of the light on the cut-off line indicated by point A in FIG. 3B is x = 0.362 and y = 0.358, and the light intensity in the center of the light distribution pattern indicated by point B is high. The chromaticity is x = 0.330 and y = 0.313.

  The chromaticity distribution in the light distribution pattern of the fog lamp 10 of the present embodiment is in the white range R defined by the ECE rule (ECE48), and the white range having a chromaticity margin with respect to the boundary line indicating the white range. Distributed within S. The chromaticity distribution in the light distribution pattern being in the white range S means that all the chromaticities of the light constituting the light distribution pattern are in the white range S.

  The chromaticity distribution in the light distribution pattern of the fog lamp 10 is distributed in a chromaticity range from red as compared with the chromaticity distribution of the white light source 1.

  As for the chromaticity at both ends of the chromaticity distribution in the light distribution pattern, the x coordinate is shifted by 0.005 or more in the plus direction as compared with the chromaticity at both ends of the chromaticity distribution of the white light source. The chromaticity at the end on the yellow side of the chromaticity distribution in the light distribution pattern has an x value on the chromaticity coordinate (CIE 1931) of 0 compared to the chromaticity at the end on the yellow side of the chromaticity distribution of the white light source. .025 shift, and the chromaticity at the end of the blue side is shifted by 0.017 in the x value on the chromaticity coordinate (CIE1931) compared to the chromaticity at the end of the blue side of the chromaticity distribution of the white light source. doing.

  In other words, by providing the color top coat, even when the chromaticity distribution of the white light source falls within the standard white range R, the chromaticity at the end of the yellow side of the chromaticity distribution in the light distribution pattern can be reduced. The x value on the chromaticity coordinate (CIE1931) can be larger than the chromaticity at the end of the chromaticity distribution of the white light source in the range of 0.005 to 0.03, and the light distribution of the fog lamp The chromaticity distribution in the pattern can be within the white range S with a margin. Therefore, by using a reflector having a color top coat, it is possible to easily satisfy the white range R on the CIE chromaticity diagram stipulated by laws and regulations for the light distribution chromaticity of the vehicle headlamp. . Compared to conventional vehicle headlamps that do not have a color top coat, the chromaticity range of white light sources that can be used as a light source can be widened, and the white light source does not require the same rigorous selection as before. It can be.

  In particular, by providing a color top coat, the chromaticity of the fog lamp can be expressed by the coordinate values (x, y) on the chromaticity coordinates (CIE1931) of (0.315, 0.292), (0.370, 0.333). , (0.370, 0.382), (0.315, 0.346) can be included in a range S surrounded by a straight line, and there is a margin in the white range R defined by the ECE rule (ECE48). You can hold it.

  Further, even when the chromaticity distribution of the white light source is out of the standard white range R, the chromaticity distribution in the light distribution pattern of the fog lamp can be within the white range R and the white range S). .

  The shift amount of the chromaticity of the light distribution pattern with respect to the chromaticity of the light emitted from the white light source is the x value of the chromaticity coordinates of the yellow side end and the blue side end when the respective chromaticity distributions are compared. It is preferably 0.005 or more and 0.03 or less, and particularly preferably 0.01 or more and 0.025 or less. This is because the irradiation light of the fog lamp can be surely distributed with a margin within the standard white range, and the decrease in light intensity can be suppressed.

  The shift amount of the chromaticity by the color top coat and the shift direction on the chromaticity coordinates can be adjusted by the type, concentration, thickness of the color top coat layer, and the like.

  Note that the vehicle headlamp of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications are made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the fog lamp is described as the vehicle headlamp. However, the present invention can be applied to all vehicle headlamps such as a headlamp and a daytime running lamp.

  For example, in the above-described embodiments, the optical system including the reflector is described as the optical system. However, the present invention can also be applied to a projector-type optical system that includes a reflector and a projection lens.

  For example, in the above embodiment, an LED chip is used as the semiconductor light emitting element, but an LD (laser diode) chip can be used instead of the LED chip.

  For example, in the above-described embodiment, the reflector 2 using the color top coat 7 having the function of protecting the reflection film as the absorption film has been described. For example, as shown in FIG. A reflector having a protective film (clear top coat) 9 laminated thereon may be used.

  For example, in the above embodiment, the reflector has been described with a three-layer structure in which the reflective film 6 and the color topcoat 7 are sequentially laminated on the molded resin substrate 5, but an appropriate layer may be laminated for function addition. For example, an undercoat layer may be provided.

  For example, in the above embodiment, a white light source in which a phosphor layer having a substantially uniform thickness is disposed on a semiconductor light emitting element is used, but the shape and position of the phosphor layer can be changed as appropriate. For example, a white light source in which a dome-shaped phosphor layer is disposed on a semiconductor light emitting element as shown in FIG. It may be more yellow than the degree.

  For example, in the above embodiment, a blue light emitting LED chip is used as the semiconductor light emitting element and a yellow light emitting phosphor is used as the phosphor, but an ultraviolet light emitting LED chip is used as the semiconductor light emitting element, and a blue light emitting phosphor and a yellow light emitting phosphor are used as the phosphor. It is good also as a structure to use.

For example, in the above embodiment, the color top coat which is an absorption film is formed in the entire region of the reflector, but may be formed in a part of the region.
[Comparative example]

  Below, the vehicle headlamp of the comparative example of this invention is demonstrated. The vehicle headlamp of the comparative example is obtained by changing the color top coat in the embodiment to a clear top coat. Except for changing the color top coat to a clear top coat, it has the same configuration as the vehicle headlamp of the example. The clear top coat is made of resin and functions as a protective film for the reflective film. The clear topcoat differs from the color topcoat in that it does not contain a dye that absorbs light of a predetermined wavelength.

  The chromaticity distribution of the white light source in the vehicle headlamp of the comparative example is as shown in FIG. 4 as in the example, and x = 0.313, y = 0. It is distributed on a straight line from 313 to x = 0.337 and y = 0.357 closer to yellow.

  FIG. 7 shows the chromaticity distribution in the light distribution pattern of the vehicle headlamp of the comparative example. Eight points (including both ends and the center) on the reference line V in the vertical direction are yellow from x = 0.313 and y = 0.315 (shown by black circles in FIG. 7) closer to blue on the chromaticity coordinates. It was distributed on a straight line until x = 0.345 and y = 0.367 (shown by black circles in FIG. 7). The chromaticity of the light irradiated on the cut-off line is x = 0.345 and y = 0.367, and the chromaticity of the light irradiated on the high luminous area at the center of the light distribution pattern is x = 0. 313, y = 0.315.

  The chromaticity distribution in the light distribution pattern of the vehicle headlamp of the comparative example was almost the same as the chromaticity distribution of the white light source. The slight difference in the chromaticity distribution seems to be due to the clear top coat.

And although the chromaticity distribution in the light distribution pattern of the vehicle headlamp of the comparative example is within the white range R defined by the ECE rule (ECE48), there is a margin with respect to the boundary line indicating the white range R. It became nothing. In the chromaticity distribution, the chromaticity of the blue end and the yellow end both have a chromaticity margin and are suitable for satisfying the light distribution of the vehicle headlamp, that is, the coordinate value ( x, y) is surrounded by a straight line connecting (0.315, 0.292), (0.370, 0.333), (0.370, 0.382), (0.315, 0.346) Was out of range.

1: White light source 2: Reflector 3: Semiconductor light emitting element 4: Phosphor 5: Substrate 6: Reflective film 7: Color top coat (absorbing film)
8: Absorption film 9: Clear top coat 10: Vehicle headlamp

Claims (5)

A white light source comprising a semiconductor light emitting element and a phosphor;
An optical system including a reflector that irradiates light emitted from the white light source forward;
The reflector includes an absorption film on a reflection surface,
The absorption film has optical characteristics such that chromaticity of light transmitted through the standard light A is 0.4 ≦ x and 0.1 ≦ y ≦ 0.4 on chromaticity coordinates (CIE1931). Vehicle headlamps. The light emission of the white light source and the irradiation light of the vehicle headlamp each have a chromaticity distribution,
The chromaticity of the end portion on the yellow side in the chromaticity distribution of the irradiation light of the vehicle headlamp is compared with the chromaticity of the end portion on the yellow side in the chromaticity distribution of the light emission of the white light source,
2. The vehicle headlamp according to claim 1, wherein an x value on a chromaticity coordinate (CIE1931) is large in a range of 0.005 to 0.03. The light emission of the white light source and the irradiation light of the vehicle headlamp each have a chromaticity distribution,
In the chromaticity distribution of the irradiation light of the vehicle headlamp, the coordinate values (x, y) on the chromaticity coordinates (CIE1931) are (0.315, 0.292), (0.370, 0.333). , (0.370, 0.382), (0.315, 0.346) within a white range surrounded by a straight line,
3. The vehicle headlamp according to claim 1, wherein a part of the chromaticity distribution of light emission of the white light source is outside the white range. The reflector includes a base, a reflective film, a top coat,
The vehicular headlamp according to any one of claims 1 to 3, wherein the top coat includes a dye that absorbs light having a predetermined wavelength to form the absorption film. The semiconductor light emitting device is an InGaN-based blue LED having a light emission peak wavelength of 470 nm or more and 475 nm or less,
The vehicular headlamp according to any one of claims 1 to 4, wherein the phosphor is a yellow light-emitting phosphor having an emission peak wavelength of 555 nm or more and 575 nm or less.

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