PROJECTOR-TYPE HEADLIGHT FOR VEHICLES

Abstract: The projector-type headlight for vehicles has a dish-shaped relector (10) with a concave mirror surface (10a) comprising a multiplicity of small surface elements and a light source (12) arranged with its light axis on the axis (Z) of the reflecting mirror. A portion of the light rays reflected by the reflector are obstructed by a shade (16) which has an optically effective edge making a light/dark interface. This edge is disposed near the meridional image surface of a convex lens (14) disposed within the path of the light beam shaped by the shade.

Description: The present invention relates to a projector type headlamp for vehicles in accordance with the preamble of claim 1. It has been necessary for the headlamp for vehicles, particularly automobiles to have a distribution pattern such that the front of own lane is brightly illuminated and further any dazzling is not given to the automobiles running on the opposite lane. There has been proposed a so-called projector type headlamp as a headlamp having the distribution pattern satisfying such requirement mentioned above, a simple lens arrangement, and a compact size. For example, U.S. Patent No. 4,511,955 (see also EP-A-0 094 518) discloses the headlamp of such type in which the reflecting surface of the reflector is formed in a revolutional ellipse and the luminosity distribution of a pattern is dependent on the formation of the reflector even though a particular distribution pattern can be obtained. Namely, it is possible to change the luminosity distribution of the distribution pattern in a constant range by changing the eccentricity of the ellipse, however it is the luminosity distribution inherent in an ellipse and it has a constant similarity. EP-A2-0 153 485 discloses a projector type headlamp for vehicles having a reflecting mirror formed in a dish-like shape and having an inner surface as a reflecting surface, a light source an optical axis of which is coincident with the axis of said reflecting mirror, a shade having an edge optically effective for making a light-dark boundary by blocking a portion of the light emitted from said light source and reflected by said reflecting surface, and a convex lens disposed within a region defined by the light beams formed by said shade. The reflecting surface is elliptically shaped, with the eccentricity of the ellipse increasing from the vertical axial center cross section to the horizontal axial center cross section in order to provide a scattering of light in the lateral direction. An increased light scattering may be achieved by providing light scattering elements in certain regions for scattering the light in a horizontal direction. The luminosity distribution pattern is thus generally determined, in the prior art, by the formation (a revolutional ellipse surface, a revolutional parabolic surface) of the reflector's surface, so that there is not sufficient freedom in design for obtaining a desired luminosity distribution. The object of the present invention is to present a novel headlamp of the projector type in which the above-mentioned drawbacks of the conventional headlamp of the projector type are eliminated. The other object of the present invention is to present a headlamp in which the reflecting surface of the reflector is composed of a great many minute face elements connected with each other continuously and smoothly, where the orientation of each face element is different from each other so as so obtain a desired luminosity distribution, and is setable voluntary to a distribution pattern having a desired luminosity distribution. Still an object of the present invention is to present a projector type headlamp in which the orientation of each face element is decided such that the maximum luminosity region in the distribution pattern is substantially not affected by any influence of a shade for providing a light-dark boundary. The reflecting surface of the reflector of the projector type headlamp of the present invention is not the surface decided by a geometrical surface such as a revolutional ellipse surface and a revolutional parabolic surface, but is composed of a great many minute face elements connected with each other continuously and smoothly; the orientation of each face element is previously decided such that the light incident from a light source is reflected toward the vicinity of the meridional image plane of the lens and a predetermined luminosity distribution can be obtained at the position of the shade. By this the distribution pattern having a desired luminosity distribution can be obtained voluntarily. The orientation of the face element with respect to an optical axis can be decided such that the light incident from the light source is reflected to the vicinity of the meridional image surface of the convex lens, and the distance between the optical axis and the point at which the reflected light from each face element is reached on the meridional image surface, can be obtained as a function of a distance between each face element and the plane substantially perpendicular to the meridional image surface and including the optical axis. By selecting the function suitably, it is possible to increase the luminous intensity of the central portion, and to increase the solid angle, and further to increase the meridional luminous intensity, thereby effectively utilizing the reflected light. Furthermore, it is also possible to decide the orientation of each face element to the optical axis such that the incident light from the light source is reflected toward the vicinity of the meridional image surface of the lens, and then the maximum luminosity region can be formed above the shade's edge. Therefore, the reflected light can be utilized to the maximum extent, since the maximum luminosity region of the distribution pattern is not blocked substantially by the shade's edge for providing the light-dark boundary. In the drawings, Figs. 1 to 15 show a first embodiment of the projector type headlamp of the present invention, in which Fig. 1 is a side view schematically showing the construction of the headlamp, Fig. 2 is a plane view of the same, Fig. 3 is a front view of the same, Figs. 4 and 5 are views for explaining the optical characteristic of the reflector of the present invention, Fig. 6 is a schematic front view showing the arrangement of the reflecting surface of a reflector composed of a plurality of face elements, Fig. 7 is a schematic enlarged view showing a quarter of the reflecting surface of the reflector shown in Fig. 6, Fig. 8 is a view showing the function X s = 0.5 X n for deciding the luminosity distribution, Fig. 9 is a view for explaining the optical characteristic of each face element by using the function of Fig. 8, Fig. 10 is a schematic view for showing the distribution pattern, Fig. 11 is a schematic view showing the luminosity distribution of the distribution pattern, Fig. 12 is a view for explaining the optical characteristic of each face element in the case where the function for deciding the luminosity distribution is set to X s = 0.125 X n ², Fig. 13 is a schematic view showing the luminosity distribution in the case of X s = 0.125 X n ², Fig. 14 is a schematic view showing a distribution pattern in the position of a shade and Fig. 15 is a schematic view showing the distribution pattern at a distance of 10 m from the light source. Fig. 16 is a schematic side view showing a headlamp using a plate-like shade. Figs. 17 to 19 are views showing a second embodiment of the projector type headlamp of the present invention, in which Fig. 17 is a view for explaining the optical characteristic of the reflector, Fig. 18 is a schematic front view showing the arrangement of each face element composing the surface of the reflector and Fig. 19 is a schematic view showing a luminosity distribution. Figs. 20 and 21 are views showing a third embodiment of the projector type headlamp of the present invention, in which Fig. 20 is a view for explaining the optical characteristic of the reflector and Fig. 21 is a schematic front view showing the arrangement of each face element composing the reflecting surface of the reflector. Figs. 22 and 23 are views showing a fourth embodiment of the projector type headlamp of the present invention, in which Fig. 22 is a view for explaining the optical characteristic of the reflector and Fig. 23 is a schematic front view showing the arrangement of each face element composing the reflecting surface of the reflector. Figs. 24 and 25 show a fifth embodiment of the projector type headlamp of the present invention, in which Fig. 24 is a schematic view for showing the distribution pattern on the shade showing the positional relationship between the maximum luminosity region and the edge of the shade and Fig. 25 is a schematic view for showing the distribution pattern at a distance of 10 m from the light source. The embodiments of the projector type headlamp of the present invention will be explained hereinafter. Figs. 1 to 15 show a first embodiment of the present invention. In the figures, numeral 10 denotes a reflector formed as a concave mirror but not formed in a particular curved surface such as a revolutional parabolic surface and a revolutional ellipse surface. The center axis of the reflector 10 is the Z axis as shown in Fig. 1, and the optical axis of a convex lens 14 is aligned with the center axis of the reflector 10. Numeral 12 denotes a halogen bulb including a filament F as a light source, and the center of the filament F is arranged to be on the Z axis and in parallel with the X axis. A shade 16 is disposed between the reflector 10 and the convex lens 14, and the edge 15 positioned at the topmost end thereof is disposed at the vicinity of a meridional image line a-b of the convex lens 14. Actually, the meridional image surface is a portion of an approximate sphere, and the curve indicated as a-b in Fig. 2 shows an intersection between the horizontal plane (X-Z plane) including the optical axis and the approximate sphere. The reflecting surface 10a of the above-mentioned reflector 10 is adapted to reflect the light beam coming from the light source F to the meridional line a-b of the convex lens 14. As shown in Fig. 3, the shade 16 has an edge 18 slanted such that the edge is spaced apart from the meridional image line a-b located on X-Z plane, and the edge 18 is arranged to pass through a portion of the light reflected from the reflecting surface 10a and directed in the downward direction. The light beam passing the shade 16 is condensed by the convex lens 14 as mentioned hereinafter and emitted forwardly. The reflecting surface 10a of the reflector 10 according to the present invention is not a geometrically determined curved surface such as a revolutional ellipse surface or a revolutional parabolic surface, but composed of a plurality of minute face elements for reflecting the light beam coming from the light source to a predetermined portion or a predetermined point apart from the light source. Its details will be explained specifically hereinafter. Referring to Fig. 4 there is schematically shown a profile of the portion at which the reflecting surface 10a of the reflector 10 crosses the X-Z plane, where X, Y and Z axes denote horizontal, vertical and the center axes of the reflector 10, respectively. The light source F is disposed on the Z axis apart from the center 0 of the reflector 10 with a predetermined distance, and the orientation N of a face element Q n is decided such that the light reflected on the face element Q n of the reflecting surface 10a is directed to the point S on the meridional image line a-b of the convex lens 14 as three-dimensionally shown in Fig. 5. Similarly, the light reflected on the face element located on the center O of the reflecting surface 10a is directed to the point S₁ on the meridional image line a-b through the light source F, and the light reflected on an other face element Q m apart form the face element Q n is directed to the point S₂ on the meridional image line. As mentioned above, the orientation of each of face elements Q n and Q m is decided. Fig. 6 schematically shows the arrangement of the face elements in view of the Z axis, Fig. 7 shows the quarter portion in Fig. 6 in an enlarged scale. Each face element has a minute region ΔS having the area of ΔX · ΔY (Δx = Δy = 0.2 mm and ΔS = 0.4 mm² in this embodiment), and a minute face element Q₀ is disposed at the position corresponding to the center O. At the position corresponding to X = 0, there are continuously disposed many face elements from Q₀ to Q₁ in the positive direction of the Y-axis except the face element Q₀, further to Q₂ in the negative direction. The orientation of each member of the face element groups as represented by these Q₁-Q₀-Q₂ is actually sequentially decided on the basis of the face element Q₀, and the orientation of each face element is decided such that all of the light beams reflected on the face elements are concentrated to the point S₁ on the meridional image surface crossing the optical axis. On the basis of the orientation of each face element of the group Q₁-Q₀-Q₂, the orientation of each of the face element groups (± Δx) adjacent to the face element group Q₁-Q₀-Q₂ is decided, and the light reflected on the face element corresponding to x = + Δx and the light reflected on the face element corresponding to x = - Δx are respectively concentrated at different points on the meridional image surface spaced apart from each other by a predetermined distance between positions in the minus and plus directions, respectively. Each orientation of each face element is thus decided, and all light reflected on the face element group Q₃-Q n -Q₄ on the position X = _ X n having the distance X n from the center O is concentrated at point S on the meridional image surface having the distance X s from the optical axis. (In the figure a portion of the face element group corresponding to X = + X n is omitted for the sake of simplicity.) Furthermore, the light reflected on the face element group including the face element Q m apart from the optical axis is adapted to be concentrated at the point S₂ on the meridional image plane having a larger distance from the optical axis than the point X s . The relationship between the above-mentioned X n and X s is decided by the fact how the desired luminosity distribution L along the meridional image line a-b is set. For example, X s can be expressed as a function of X n as follows. X s = f(X n ) The function f(X n ) may be of several types such as a first order linear function, a second order linear function, a high order linear function or an exponential function, and further the function f(X n ) may be a conbination thereof. For example, if f(X n ) = 0.5X n , X₃ becomes X s = 0.5X n (Fig. 8). In this case, when X n = 2, X s = 1 and when X n = 4, X s becomes 2. In the reflector 10, the light reflected on the face elements located at the region - 2 ≦ X n ≦ 2 is concentrated at the region - 1 ≦ X s ≦ 1 on the meridional image plane, similarly the light reflected by the regions 2 ≦ X n ≦ 4 and - 4 ≦ X n ≦ -2 is concentrated at the region 1 ≦ X s ≦ 2 and - 2 ≦ X s ≦ -1 on the meridional image plane respectively. Referring to Fig. 10, a distribution pattern on a test screen provided at the vicinity of the meridional image plane is schematically shown as an equiillumination, and the luminosity distribution at that time is shown in Fig. 11, where the lines H-H and V-V show the horizontal and vertical direction of the screen, respectively. In a normal condition of the headlamp for automobiles, the luminosity distribution as shown in Fig. 11 is insufficient, and it is desirable that a high luminosity is obtained at the central portion. Then, if f(X n ) = 0.125X n ² is used, the light reflected on the face elements at the region - 2 ≦ X ≦ 2 at the reflector 10 is concentrated at the region - 0.5 ≦ X s ≦ 0.5 of the meridional image plane as shown in Fig. 12, and this is higher at the central luminosity than in the case of X s = 0.5X n ². The luminosity distribution L shown by a solid line in Fig. 13 is corresponding to the case of X s = 0.125X n ². In order to further increase the central luminosity, it is possible to express X s by a high-order linear function of X n and further by an exponential function of X n , therefore a suitable function may be used for obtaining a desired distribution characteristic. In this selection of the function, several luminosity distribution characteristics may be without any limitation due to the above examples within the mode that the maximum luminosity can be obtained at the central portion and the luminosity is symmetrically reduced in the right and left directions with increasing distance from the center. Working for forming each face element having a different orientation as mentioned above is effected by an NC working machine. The light reflected on each face element of the reflector 10 formed so as to obtain the center luminosity suitable as mentioned above is projected by the convex lens 14 in the condition that a portion of the light is blocked by the shade 16 having the upper edge at the vicinity of the meridional image plane a-b. Namely, as shown in Fig. 14, the upper half of the pencil passes through the above portion of the upper edge portion 15 of the shade 16 and the most part of the lower half is blocked by the shade 16 as shown by the solid line, and the light beam located above the slanted end portion 18 is allowed to pass as shown by dotted lines. Numeral 100 denotes the maximum luminosity region. The pencil projected forwardly by the convex lens 14 has a pattern inverted from the pattern as shown by the dotted lines in Fig. 14. Referring to Fig. 15, there is shown the equiillumination curve of the distribution pattern, when the screen is disposed at a position spaced apart from the light source F by 10 meters and a halogen bulb of H3 12 V/ 55 W in EC standard is used as the light source F. The hatched area 20 denotes the light portion blocked by the shade 16 and the edge provides a light-dark boundary 19 to the pencil 17 formed by the convex lens 14. In this embodiment, the orientation of each face element of the reflector is decided such that all light reflected on each face element is directed to a point on the meridional image line a-b of the convex lens 14, but it is possible to set the orientation of each face element such that each reflected light is directed to a point disposed between the meridional image surface and the sagittal image surface of the lens 14. Furthermore, it is also possible to form a shade 16′ as shown by the dotted line in Fig. 16 as a plate perpendicular to the optical axis, and in this case a convex lens 14′ having a curvature larger than the convex lens in the first embodiment may be used and the convex lens 14' may be disposed such that the plate 16′ is in contact with the meridional image line a′-b′. By this, a similar effect can be expected within the actually required tolerance in comparison with the above-mentioned enbodiment in which the shade is curved along the meridional image line a-b of the convex lens. Referring to Figs. 17 and 18, there is shown an arrangement of face elements composing the reflector and the optical characteristic of the reflector in a second embodiment made of an optical system similar to the first embodiment. In this embodiment, the reflecting surface 10a of the reflector 10 is devided by the planes 100 (X = - D₁) and 101 (X = D₁) into a central reflection portion M and marginal reflection portions C, the two planes 100 and 101 are parallel with the plane (Y-Z plane) perpendicular to the meridional image line a-b of the convex lens 14, including the optical axis, and spaced apart from the optical axis by a distance D₁. The orientation of the face element Q n in the center reflection portion M is decided such that the light from the optical source F is reflected to the point S on the meridional image line. The orientations of face elements located at the same distance from the plane including the optical axis and in parallel with the meridional image line substantially are concentrated at the same point onthe meridional image line a-b. For example, the light reflected not only on the face element Q n located on X = - X n but also on the face elements Q₃ and Q₄ located on the same X = - X n , is concentrated at the same point S (X = - X s ) on the meridional image plane. Therefore, the orientation of other face elements in the central reflection portion M is decided by introducing a suitable function for satisfying X s = f(X n ) by means of the manner as mentioned in the first embodiment. The function f may be selected preferably as a second order linear function such as X s = 0.125 X n ². The orientation of each face element in the marginal reflection portions C is decided such that all light from the optical source is reflected to the point S₁ (X = 0) on the meridional image plane a-b. This means that the marginal reflection portions C compose a portion of the revolutional ellipse surface 30 having a primary focus at the optical source F and a secondary focus at the point S₁. The light incident from the light source F to the marginal reflection portions C is reflected in the direction as shown by the arrows A and B to be concentrated at the point S₁, and the luminosity distribution due to those light beams is shown by the dotted line 31 in Fig. 19. If a desired luminosity distribution L is as shown by the solid line in Fig. 19, the orientation of each face element in the central reflection portion M of the reflector should be decided such that the luminosity distribution is subtracted with the luminosity distribution due to the marginal reflection portions C from the luminosity distribution L. In actual manufacturing, the orientation of the face elements at the vicinity of the center portion is calculated such that the light emitted from the light source F to the vicinity of the center O of the reflector is reflected to the direction as shown by the arrows E and F (i.e. the direction in which the light is directed to the point comparatively shifted from the point S₁ at which the optical axis crosses the meridional image line a-b). Namely, the orientation of each face element located at the vicinity of the center O of the central reflection portion M should be decided by using a modified function without using the above-mentioned linear function. However, in the case where the formation of the vicinity of the center O is made similar to that one of the first embodiment, the light incident to the vicinity of the center O is reflected to the point comparatively adjacent to the point S₁ of the meridional image surface, therefore the luminosity distribution on the shade becomes in actual fact such that the luminosity distribution L is added to the luminosity distribution due to the revolutional ellipse surface 30 as shown by the dotted line 31, thereby, increasing further the luminosity at the central portion of the shade. Referring to Figs. 20 and 21 there are shown the optical characteristic of the reflector and the disposition of each face element in a third embodiment of the present invention, composed of a similar optical system as the first embodiment as mentioned above. In this embodiment, the reflecting surface 10a of the reflector 10 is divided into a central reflection portion M′ and marginal reflection portions C′ by two planes 102 (X = - D₂) and 103 (X = D₂) parallel with the plane (Y-Z plane) approximately perpendicular to the meridional image line a-b of the convex lens and spaced apart from the optical acis by the equidistance D₂, respectively. The orientation of each face element of the central reflection portion M′ is decided such that all light incident from the light source is directed to the point S₁ (X = 0) at which the optical axis crosses the meridional image line a-b. This shows that the face element located in the central reflection portion M′ of this embodiment forms approximately a portion of the revolutional ellipse surface having a first focus at the light source F and a second focus point at the point S₁, as similar to the marginal reflection portion C in the second embodiment. On the other hand, each face element in the marginal reflection portion is decided by introducing the function suitably satisfying the equation X s = f(X n ) similar to the face element in the central reflection portion M of the above-mentioned embodiment, and the function such as X s = 0.125X n ² is selected. Since the central reflection portion of the reflector is approximately formed by a portion of the revolutional ellipse surface 40, the reflected light is concentrated to the cross point S₁ between the optical axis and the meridional image line a-b thereby increasing the central luninosity distribution with respect to the left and right directions, therefore there is provided some degree of freedom with respect to the setting of the orientation N of each face element Q n in the marginal reflection portion C′ of the reflector 10. Namely, the desired luminosity distribution is obtained in the vicinity of the shade by the central reflection portion M′ of the revolutional ellipse surface 40, therefore it is possible to freely control the orientation of each face element Q n in the marginal reflection portions C′ thereby obtaining different luminosity distributions in the vicinity of the shade. Especially, the light incident from the light source F is effectively reflected to the vicinity of the shade by the marginal reflection portions C′, therefore the light is utilized effectively. Referring to Figs. 22 and 23 there are shown the optical characteristic of the reflection and the distribution of each face element in a fourth embodiment of the present invention, composed of a similar optical system as the first embodiment mentioned above. The reflecting surface 10a of the reflector is composed of a central reflection portion M″, two intermediate reflecting portions B adjacent to the central reflection portion M", two marginal reflection portions C″ adjacent to the intermediate reflecting portions B, respectively. The central reflection portion M" and the intermediate reflecting portions B are divided by two planes 104 (X = - D₃) and 105 (X = D₃) which are parallel to the plane including the optical axis and perpendicular to the meridional image plane a-b and are spaced apart from the optical axis by the same distance. The intermediate reflecting portions B and the marginal reflection portions C′ are divided by two planes 106 (X = - D₄) and 107 (X = D₄), respectively. The curved surface 50 of the central reflection portion M″ is formed in a horizontal section as a portion of a parabola having a focus F at the light source F, and is formed in a vertical section as a portion of an ellipse having a first focus at the light source F and a second focus at the meridional image line. Namely, this is the same as deciding the orientation of the face element by applying a first order linear function expressed by X s = X n (- D₃ < X n ≦ D₃). The curved surface 50 is formed such that all of the light incident from the light source F on the portions having the distance Di (0 ≦ Di ≦ D₃) from the Y-Z plane, is reflected to the direction parallel to the Y-Z plane and concentrated at the common point Si having a distance from the optical axis on the meridional image line. Therefore, there is provided a distribution pattern such that the light is distributed to the wider extent of the peripheral portion of the shade 16. The orientation of each face element in the marginal reflection portions C″ is decided such that the light incident from the light source F is concentrated to the cross point S₁ of the meridional image line. Such face elements are approximately formed as a portion of the revolutional ellipse surface 40 having the first focus at the light source F and the second focus at the point S₁. Namely, it is featured with X s = 0 (X n ≦ - D₄ or X n ≧ D₄). Furthermore, the orientation of each face element in the intermediate reflecting portions B is decided in view of a contribution to the desired luminosity distribution due to the reflected light in the central reflection portion M″ and the marginal reflection portions C″. The X s in the case where - D₄ < X n < - D₃ or D₃< X n < D₄ isexpressed as X s = f(X n ), and there is selected a function for giving the orientation of each face element Q n so as to obtain a luminosity in which the contribution due to the light reflected on the revolutional ellipse surface 40 and the contribution due to the light reflected on the curved surface 50 are subtracted from the luminosity distribution on the shade. In the embodiment, the curved surface 50 is formed such that the central reflection portion M″ is, in a horizontal section, a portion of a parabola having a focus at the light source F, and in a vertical section, a portion of an ellipse having a first focus at the light source F and a second focus at the point of marginal reflection portion. The curved surface 50 is formed so as to at least have a parabola in the horizontal section, and it is not necessary to have a parabola in the vertical section. The reflecting surface in the conventional case where the reflecting surface is formed by only a revolutional ellipse surface, is shown by the dotted line 41 in Fig. 22. The thickness of the reflector in the direction of the optical axis is reduced by the reflecting surface of this embodiment. In each embodiment as mentioned above, as shown in Figs. 14 and 15 the light reflected at each face element of the reflector provides a distribution pattern having a light shade boundary 19 formed by the edges 15 and 18 of the shade 16, and a portion of the reflected light to be concentrated to the maximum luminosity region 100 is blocked by the shade 16 because the edge 15 of the shade 16 is located on the horizontal plane including the optical axis. In order not to lose the reflected light to be concentrated at the maximum luminosity region by using the optical system similar to that of the first embodiment, it is necessary that the orientation of each of the face elements composing the reflecting surface is decided such that the center of the maximum luminosity region 100 is formed above the edge 15 of the shade 16. Fig. 24 shows a schematic distribution pattern at the position of the shade 16 as mentioned above. There is disposed an optical system where the light source F is disposed on the axis of the reflector, the optical axis of the convex lens 14 is coincident with the axis of the reflector, and further the edge 15 of the shade 16 is disposed along the meridional image line a-b. A halogen bulb of H3 12V/55W of EC standard is used for the light source F, and the halogen bulb has a filanent of 5.5 mm in length and 0.8 mm in diameter In the case where the distance between the center of the light source F and the center O of the reflector of the first embodiment is 15 mm, and the distance from the light source F to the cross point S₁ between the optical axis and the meridional image surface is 50 mm, it is recognized that the distance h between the center of the maximum luminosity region 100 in the position of the shade 16 and the edge 15 of the shade 16 is about 2 mm. Specifically, the orientation of each face element is decided such that the light incident from the light source F is directed to the point on the curve a″-b″ of the meridional image line located above the curve a-b of the meridional image plane by about 2 mm. The distribution pattern at the position spaced apart from the light source F by 10 m is as shown in Fig. 25, and the proportion that the maximum luminosity region 100 is blocked by the shade 16 is reduced, thereby effectively utilizing the light emitted from the light source F. With respect to the above mentioned h the above effects are recognized within the region of 0.5 mm ≦ h ≦ 5 mm, however no effect is obtained in the region of h < 0.5 mm and h > 5 mm in actual fact. In the embodiment of the headlamp for vehicles of the present invention as mentioned above, the wording "vicinity of the meridional image surface of a convex lens" means the region including the meridional image surface per se and until the sagittal image plane of the convex lens substantially. Furthermore, a halogen bulb having a filament is used as a light source in the above embodiment, however a discharge lamp may be used.

Claims: 1. A projector type headlamp for vehicles comprising a reflecting mirror (10) formed in a dish-like shape and having an inner surface as a reflecting surface (10a), a light source (12) having a filament (F) so disposed that at least part of the filament (F) is coincident with the axis of said reflecting mirror (10) a shade (16) having an edge optically effective for making a light-dark boundary by blocking a portion of the light emitted from said light source (F, 12) and reflected by said reflecting surface (10a), and a convex lens (14) disposed, with its optical axis aligned with the centre axis of the reflecting mirror (10), within a region defined by the light beams formed by said shade (16). characterized in that the upper edge of said shade (16) is disposed at the vicinity of a meridional image line (a-b, a″-b″) of said convex lens (14), defined by the intersection of the meridional image surface with a horizontal plane and that said reflecting surface (10a) is formed by a great many minute face elements (Q₀, Q₁, Q₂, Q₃, Q₄, Q n , Q m ) smoothly connected with each other, each orientation (N) of each of said face elements (Q₀-Q m ) with respect to said optical axis being decided in such a manner that the light incident from said light source (F, 12) is reflected to the vicinity of said meridional image line (a-b) and a desired luminosity distribution (L) can be obtained at the position of said shade (16). 2. A projector type headlamp for vehicles according to Claim 1, wherein said reflecting surface (10a) is composed of a plurality of face element groups (Q₁-Q₀-Q₂) disposed at both sides of a vertical plane (Y-Z) including said optical axis (Z) with a predetermined distance, each said face element group (Q₁-Q₀-Q₂) being composed of many face elements located equidistant from said vertical plane (Y-Z), the orientation of each face element of said element group being decided such that the light from said light source (F) is concentrated at the same point (S₁, S) at the vicinity of said meridional image line (a-b) of said lens (14), and the distance X s between said optical axis and said points (S₁, S) being given as a function of the distance X n between each of said face element group and said vertical plane (Y-Z). 3. A projector type headlamp for vehicles according to Claim 1, wherein said orientation of each of said face elements is decided such that the light incident from said light source (F) is reflected to the vicinity of said meridional image line (a-b) to form a maximum luminosity region (100) above the said upper edge of said shade (16). 4. A projector type headlamp for vehicles according to Claim 3, wherein said meridional image line (a″-b″) is defined by the intersection of the meridional image surface with a horizontal surface located above said optical axis to form said maximum luminosity region above the edge of said shade. 5. A projector type headlamp for vehicles according to Claim 2, wherein said reflecting surface (10a) is divided into a central reflection portion (M) and marginal reflection portions (C) by two planes (100, 101) parallel with the said vertical plane (Y-Z) and spaced apart from each other and spaced from said optical axis by a predeterminted distance (D₁), the orientation of each face element in said central reflection portion (M) being decided such that X s = 0 and the orientation of each face element in said marginal reflection portions (C) being decided such that X s is expressed by a linear function of X n . 6. A projector type headlamp for vehicles according to Claim 2, wherein said reflecting surface (10a) is divided into a central reflection portion (M′) and marginal reflection portions (C′) by two planes (102, 103) parallel with the said vertical plane (Y-Z) and spaced apart from each other and spaced from said optical axis by a predetermined distance (D₂), the orientation of each face element of said central reflection portion (M′) being decided such that X s is expressed by a linear function of X n , and the orientation of each face element in said marginal reflection portions (C′) being decided such that X S = 0. 7. A projector type headlamp for vehicles according to Claim 2, wherein said reflection surface is divided into a central reflection portion (M″), intermediate reflection portions (B) and marginal reflection portions (C″) by two planes (104, 105) parallel with the said vertical plane (Y-Z) and spaced apart from each other and spaced from the optical axis by a predetermined distance (D₃), and further by two other planes (106, 107) parallel with said vertical plane (Y-Z) and spaced apart from each other and spaced from said optical axis by a distance (D₄) larger than said predetermined distance (D₃), the orientation of each face element in said central reflection portion (M″) being decided such that X s = X n , the orientation of each face element in said intermediate reflection portions (B) being decided such that X s is expressed by a linear function of X n , and the orientation of each face element in said marginal reflection portions (C″) being decided such that X s = 0. 8. A projector type headlamp for vehicles according to any one of claims 1 to 3, wherein said shade is formed as a plate (16′) arranged perpendicular to said optical axis and said convex lens (14′) is disposed such that said plate (16′) is in contact with said meridional image line (a′-b′).

Inventors: NAKATA, YUTAKA
Applicants: ICHIKOH INDUSTRIES LIMITED
Application year: 1986
Main classification: F21M3
IPC codes: F21V7