JP2011146133A - Head lamp for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small head lamp for a vehicle providing a light distribution suitable for frontward lighting of a vehicle. <P>SOLUTION: The head lamp includes a reflector 2 of pyramid tube type whose front end opening 21 is larger than a rear end opening 22, an LED1 arranged at the rear end opening 22 of the reflector 2, and a projection lens 3 arranged to face the front end opening 21 of the reflector 2. The reflector 2 includes upper, lower, left, and right reflecting surfaces 2r, 2d, 2l, and 2r each having a parabolic shape with LED1 as a focal point. The projection angle of the light emitted from the reflector 2 is larger in lateral direction than in vertical direction. The front end edge of the lower reflecting surface 2d has such shape as corresponds to cutoff line of low beam distribution. The upper reflecting surface 2u has preferably a cut 23 from the front end edge toward rear side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a headlamp for a vehicle such as an automobile, and more particularly to a headlamp using a semiconductor light emitting element such as an LED (light emitting diode) as a light source.

  Various types of automobile headlamps using semiconductor light-emitting elements such as LEDs as light sources have already been proposed. In recent years, further reduction in size and weight of such headlamps has been demanded. In order to meet such demands, it is considered to configure a headlamp using a CPC (Compound Parabolic Concentrator). As described in Patent Document 1, this CPC is configured as a cone-shaped reflector whose ridgeline is a parabola or a shape close to this, and an LED is arranged in a small-diameter rear end opening, The light emitted from is reflected by the inner surface of the CPC and emitted from the front opening having a large diameter. By using this CPC, it becomes possible to project the light emitted from the LED with high efficiency, and it is possible to realize illumination with high luminous intensity even if the whole is downsized.

JP 2007-235079 A

  When the present inventor has configured a headlamp of an automobile using such a CPC, it is possible to irradiate light at a high luminous intensity to a predetermined region centered on the optical axis due to the reflection characteristics of the CPC. It was effective in achieving the objectives of miniaturization and weight reduction. However, since the light emission characteristic of CPC is highly condensing and uniform, the light irradiation area has a circular light distribution even when the light projected from the CPC is projected through the lens. At the same time, a clear light / dark boundary portion having a circular shape at the boundary between the irradiated region and the non-irradiated region is likely to occur. Therefore, when it is intended to construct a low beam light distribution of an automobile using this CPC, it is difficult to obtain a light distribution that is narrow in the vertical direction and wide in the left and right direction, and the light / dark boundary portion is along the upper edge of the so-called irradiation region. It is difficult to use as a cut line, and a light / dark boundary part also occurs in the area immediately before the own vehicle, so that the illumination of the area closer to the own vehicle than the light / dark boundary part becomes insufficient, and the headlamp of the automobile It has become clear that there are problems to be solved in these respects in order to apply as

  An object of the present invention is to provide a small and lightweight vehicle headlamp that can obtain a light distribution suitable for front lighting of a vehicle using a CPC or a reflector having a shape close thereto.

  The present invention provides a reflector formed in a prismatic cylinder shape having a front end opening larger than the rear end opening, a light emitting element disposed in the rear end opening of the reflector, and a front end opening of the reflector. The reflector is composed of upper, lower, left and right reflecting surfaces with a parabolic shape whose cross section in the axial direction is the focus of the light emitting element, and the light emitted from the front end opening has an emission angle in the left and right direction. It is characterized by being configured to be larger than the emission angle in the vertical direction.

  In the present invention, the front end edge of the lower reflecting surface of the reflector is preferably formed in a shape corresponding to the cut-off line of the low beam light distribution, and the rear focal point of the projection lens is preferably arranged in the vicinity of the front end edge. . Moreover, it is preferable that a notch is formed in the upper reflection surface of the reflector from the front edge toward the rear.

  According to the present invention, illumination with a light distribution pattern having a wider irradiation range in the left-right direction than in the up-down direction is possible, and a light distribution headlamp suitable for illuminating the front of the vehicle can be configured. In particular, a head capable of low beam light distribution having a required cut-off line by forming the front end edge of the lower reflection surface of the reflector in a shape corresponding to the cut-off line and arranging the rear focal point of the projection lens in the vicinity of the front end edge. A lamp can be configured. Furthermore, by forming a notch in the upper reflecting surface of the reflector, it is possible to configure a light distribution headlamp in which the luminous intensity is suppressed and the luminous intensity gradient is relaxed without producing a clear brightness boundary in the near-front illumination.

The longitudinal cross-sectional view along the lamp | ramp optical axis of the lamp unit of embodiment of this invention. The external appearance perspective view of the principal part of a lamp unit. The expansion perspective view and front view of a reflector. The vertical cross section of a reflector, a horizontal cross section, and an optical path figure. The pattern diagram of low beam light distribution and high beam light distribution. The top view which shows the modification of a notch.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view along a lamp optical axis showing a schematic configuration of an embodiment in which the present invention is applied to a headlamp of an automobile, particularly a headlamp with low beam distribution. Although not shown in the drawing, a lamp housing is composed of a container-shaped lamp body and a transparent front cover attached to the front opening of the lamp body, and the lamp unit LU shown in FIG. Decorated. The lamp unit LU includes a light source 1, a reflector 2, and a projection lens 3. The light emitted from the light source 1 is reflected by the reflector 2, and further refracted by the projection lens 3 and passes through the front cover. It is comprised so that it may irradiate toward the front area of a car. The projection lens 3 has a function of condensing light. Here, the projection lens 3 has a function of condensing in the vertical direction, and is configured as a cylindrical lens having a function of diffusing in the horizontal direction. .

  FIG. 2 is an external perspective view of the main part of the lamp unit LU. Referring to FIGS. 1 and 2, a unit base 4 made of a metal plate or the like is provided. 1 is supported, and the reflector 2 is supported on a rear horizontal wall 42 by a retainer 43. The projection lens 3 is supported by a lens frame 45 on the front horizontal wall 44 of the unit base 4. A heat sink 46 for radiating heat generated by the light source 1 is integrally provided on the rear surface of the rear side wall 41 of the unit base 4. The light source 1 is composed of an LED, but here it is composed of a surface-emitting LED having a rectangular light emitting surface. As shown in the enlarged perspective view of FIG. 3A, the reflector 2 includes four reflecting surfaces 2u, 2d, 2l, and 2r on the top, bottom, left and right when viewed from the front, and the front end opening 21 is the rear end opening. The rear end opening 22 is formed to be approximately equal to the outer dimension of the LED 1 and the LED 1 is attached thereto. The projection lens 3 is a convex lens and faces the front end opening 21 of the reflector 2.

  The reflector 22 will be described in detail. The reflector 22 is formed in a horizontally long rectangle having a horizontal dimension larger than a vertical dimension when viewed from the front. The two upper and lower reflecting surfaces 2u, 2d constituting the reflector 2 are axisymmetric with respect to the central axis of the reflector 2, that is, the reflector optical axis Rx, and the shape when cut in the vertical direction is shown in FIG. As shown in (), all are formed as parabolas. The upper reflective surface 2u is formed as a parabola with the lower edge of the rear opening 22 as a focal point Fu, and the lower reflective surface 2d is formed as a parabola with the upper edge of the rear opening 22 as a focal point Fd. The reflection surface is extended. Also, the two left and right reflecting surfaces 21 and 2r are similarly symmetrical with respect to the reflector optical axis Rx, and the shape when cut in the horizontal direction is formed as a parabola as shown in FIG. 4B. . The left reflecting surface 21 is formed as a parabola with the right end of the LED 1 disposed in the rear opening 21 as a focal point Fl, and the right reflecting surface 2r is formed as a parabola with the left end of the LED 1 as a focal point Fr. The reflecting surface is extended vertically. Further, the left and right reflecting surfaces 21 and 2r have a large inclination angle with respect to the reflector optical axis Rx, and when reflected from the LED 1, as described later, the reflecting surfaces 21 and 2r are configured to reflect at a larger angle than the upper and lower reflecting surfaces 2u and 2d. ing.

  When the reflector 2 is viewed from the front of the front end opening 21 in FIG. 3B, the right edge r is a left edge l with the front edge of the lower reflecting surface 2d as a boundary at the substantially central position in the left-right direction. The left and right edge portions are formed at different heights so as to be lower, and the center edge portion c including this center position is inclined obliquely upward to the left. Due to the inclined shape of the central edge c, a step 2dd extending along the reflector optical axis Rx from the front end opening 21 toward the rear is formed at the center in the left-right direction of the lower reflecting surface 2d. This constitutes a so-called cut-off line when performing illumination with a low beam light distribution. Further, an arc-shaped notch 23 is formed on the upper reflection surface 2u of the reflector 2 from the front end opening 21 toward the rear. The shape and size of the notch 23 are determined according to the light distribution characteristics of the low beam light distribution to be designed as will be understood from the description to be described later.

  In addition, the LED 1 is disposed in the rear end opening 22 of the reflector 2 such that the center of the light emitting surface coincides with the reflector optical axis Rx. The projection lens 3 is set at a position where the lens central axis, that is, the lens optical axis deviates vertically and parallel to the reflector optical axis Rx, and the rear focal point Fp of the projection lens 3 is that of the reflector 2. The front end opening 21 is arranged so as to coincide with or substantially coincide with the central edge c of the front end edge of the lower reflective surface 2d of the lower end surface 21d. This lens optical axis is the lamp optical axis Lx of the lamp unit.

  According to the lamp unit LU of this configuration, as shown in the horizontal optical path in FIG. 4B, when the LED 1 emits light, part of the light emitted from the light emitting surface of the LED 1 is left reflective surface 2l and right reflective surface 2r. The left reflecting surface 21 and the right reflecting surface 2r are configured as paraboloids that focus on the left and right ends Fl and Fr of the LED 1 of the rear end opening 22, and are reflected as parallel light beams. Then, the light is emitted from the front end opening 21 of the reflector 2 toward the projection lens 3. Further, another part of the light emitted from the LED 1 is emitted as direct light toward the projection lens 3 through the front end opening 21. By appropriately designing the length of the reflector 2 in the direction along the reflector optical axis Rx and the opening dimension in the left-right direction of the front end opening 21, the angle θ2 at which the reflected light is emitted and the angle θ21 at which the direct light is emitted are equal. can do. As a result, these light beams are incident on the projection lens 3 as a light beam having an incident angle within θ2 (= θ21), and are refracted and projected forward. Therefore, the incident angle θ2 and the focal point of the projection lens 3 are reflected. The illumination light has a horizontal spread angle calculated based on distance, refractive index, and the like. For example, the left and right regions are irradiated to 45 ° regions.

  On the other hand, as shown in the vertical optical path in FIG. 4A, part of the light emitted from the light emitting surface of the LED 1 is projected onto the upper reflecting surface 2u and the lower reflecting surface 2d, respectively. Since the reflecting surface 2d is a parabolic surface with the lower edge and upper edge of the rear end opening 22 as focal points Fu and Fd, respectively, it is reflected as a parallel light beam and directed from the front end opening 21 of the reflector 2 toward the projection lens 3. Are emitted. Further, another part of the light emitted from the LED 1 is emitted as direct light toward the projection lens 3 through the front end opening 21. By appropriately designing the length of the reflector 2 in the direction along the reflector optical axis Rx and the vertical opening size of the front end opening 21, the angle θ1 at which the reflected light is emitted and the angle θ11 at which the direct light is emitted are equal. can do. As a result, these lights are incident on the projection lens 3 as light fluxes having an incident angle within θ1 (= θ11), and are refracted and projected forward. For example, it irradiates an area of 22 ° above and below. However, since the notch 23 is formed in the upper reflecting surface 2u from the front end opening 21 toward the rear, the light passing through the notch 23 is emitted at an incident angle θ12 larger than θ1, and the projection lens 3 It is incident on the upper region of.

The light emitted from the front end opening 21 of the reflector 2 is irradiated forward by the projection lens 3 to form a predetermined light distribution pattern. Of the light emitted from the front end opening 21, the upper limit area of the light distribution pattern Light, that is, light emitted along the front end edge of the lower reflecting surface 2d of the reflector 2 before being inverted upside down by the projection lens 3, has different heights at the left and right edge portions r and l of the front end edge and the center. Since the edge c has an inclined shape and the front end edge is disposed in the vicinity of the rear focal point fp of the projection lens 3, the lens of the projection lens 3 is formed as an optical pattern corresponding to the shape of the front end edge. The light is irradiated on the optical axis, in other words, on the lamp optical axis Lx. As a result, as shown in FIG. 5A, a low-beam light distribution pattern Lo having a cut-off line COL corresponding to the shape of the front end edge is formed at the upper light / dark boundary.

Further, of the light emitted from the front end opening 21, the light incident on the upper region of the projection lens 3, that is, the light reflected by the lower reflection surface 2 d emitted along the front end edge of the upper reflection surface 2 u of the reflector 2 and Since direct light emitted upward from the LED 1 has a notch 23 formed at the front edge, it is emitted upward through the notch 23 and is projected at an angle θ 12 larger than the incident angle θ 1. 3 is incident on the upper region. The light that has passed through the notch 23 is irradiated by the projection lens 3 onto a region below the lens optical axis, that is, the lamp optical axis Lx, and is below the low beam light distribution pattern Lo shown in FIG. The side illumination area, that is, the near-front area of the vehicle is further expanded to the near-front area An of the vehicle, and a light distribution pattern in which the brightness gradient is relaxed without emphasizing the bright / dark boundary is formed.

As described above, the low beam light distribution pattern Lo obtained by the lamp unit LU according to the embodiment is light distribution suitable for front illumination of a vehicle that is narrow in the vertical direction and illuminates a wide area in the horizontal direction. In addition, the area near the lamp optical axis Lx that illuminates the far front area has a required cut-off line shape with a clear light / dark boundary, and the lower area that illuminates the near front area has a reduced lightness gradient and illumination over a wide range. It becomes. As a result, it is possible to illuminate the far front area brightly while preventing dazzling of the preceding and oncoming vehicles, and to illuminate the near front area over a wide range with appropriate brightness that is not excessively bright. Can be obtained. In this lamp unit LU, all of the light emitted from the LED 1 is used for low beam light distribution, so that the light use efficiency can be increased. Therefore, even if a small or low power consumption LED is used, illumination is performed at a high intensity. The light distribution pattern to be performed can be obtained. Further, a shade for obtaining a low beam light distribution pattern is unnecessary, and the lamp unit can be reduced in size and weight.

Here, the shape of the front end edge of the lower reflecting surface 2d of the reflector 2 is not limited to the shape of the embodiment, and although not shown, the left edge on the left side of the front end edge is simply inclined with respect to the left-right center position. You may make it a shape. In this case, as shown in FIG. 5B, a low beam light distribution pattern Lo2 having a cut-off line COL whose left region is inclined obliquely upward to the left from the lamp optical axis Lx is obtained.

Further, the notch formed in the upper reflecting surface 2u of the reflector 2 is not limited to the arc shape of the embodiment, but a rectangular notch 23A as shown in a plan view in FIG. 6A or FIG. ) May be formed as a triangular notch 23B, and can be designed in an appropriate shape according to the light intensity and the width when illuminating the near front. Further, as shown in FIG. 6C, a cutout 23C in which the cutout amount in the central region is reduced may be used. In particular, in the case of the notch 23C in FIG. 6C, the irradiation light intensity of the area Ann just before the vehicle shown by a broken line in FIG. 5A is somewhat reduced, and the area Ann just before is too bright. Prevents loss of visibility. In particular, it is advantageous in reducing visibility due to road surface reflected light during rainy weather or the like and preventing dazzling of other vehicles.

The embodiment shows an example applied to low beam light distribution, but the shape of the front end edge of the lower reflection surface 2d of the reflector 2 is a simple linear shape, and the position of the rear focal point Fp of the projection lens 3 is appropriately set. By adjusting, as shown in the light distribution pattern in FIG. 5B, it is also possible to realize a high beam light distribution Hi that includes a region above the lamp optical axis Lx and does not have an upper edge region cut-off line. . Even in this case, if the notch 23 is formed in the upper reflection surface 2u of the reflector 2, the near-front region An can be illuminated with a lightness gradient that does not cause a bright / dark boundary.

The light emitting element in the present invention is not limited to the LED, and any semiconductor light emitting element such as a laser diode can be applied as the light source of the headlamp of the present invention.

  The present invention can be applied to a small headlamp using a light emitting element as a light source.

1 Light source (LED)
2 Reflector 3 Projection lens 4 Unit base 21 Front end opening 22 Rear end opening 23 Notch 2u Upper reflection surface 2d Lower reflection surface 2r Right reflection surface 2l Left reflection surface Rx Reflector optical axis Lx Lamp optical axis (lens optical axis)

Claims (4)

  A reflector formed in a prismatic cylinder shape whose front end opening is larger than the rear end opening, a light emitting element disposed in the rear end opening of the reflector, and a projection lens disposed opposite to the front end opening of the reflector The reflector is composed of upper, lower, left and right reflecting surfaces with a parabolic shape whose cross section in the axial direction is the focal point of the light emitting element, and the light emitted from the front end opening has an emission angle in the left and right direction. A vehicular headlamp characterized by being configured to be larger than an emission angle in the vertical direction.   The front end edge of the lower reflection surface of the reflector is formed in a shape corresponding to a cut-off line of low beam light distribution, and the rear focal point of the projection lens is disposed in the vicinity of the front end edge. The vehicle headlamp according to claim 1.   3. The vehicle headlamp according to claim 1, wherein a notch is formed in the upper reflection surface of the reflector from the front edge toward the rear. The vehicle headlamp according to any one of claims 1 to 3, wherein the reflector, the light emitting element, and the projection lens are integrally assembled to form a lamp unit.

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