Vehicular headlamp having reflector for controlling luminous intensity distribution pattern

• US 5,171,082 A
• Filed: 01/23/1992
• Issued: 12/15/1992
• Est. Priority Date: 01/28/1991
• Status: Expired due to Term

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Watanabe, Takao
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): HEYMAN, LEONARD
• Application Number:
  US07/824,774
• Time in Patent Office: 327 Days
• Field of Search: 362/61, 362/346, 362/304, 362/215
• US Class Current: 362/518
• CPC Class Codes: F21S 41/14 characterised by the type of light source
• CPC Class Codes: F21S 41/334 the reflector consisting of patch like sectors
• CPC Class Codes: F21V 7/048 with facets structure

Abstract

A vehicular headlamp having a reflector with the capability for controlling the luminous intensity distribution so as to attain a balance between the spread of light in luminous intensity distribution in the horizontal direction and the brightness required in the central part of the distribution. The reflecting surface of the reflector is divided into a plurality of regions in accordance with the necessary action of controlling the luminous intensity distribution. Some of these regions are each formed as an assembly of hyperbolic paraboloidal reflecting elements that form a luminous intensity distribution pattern that is broadly diffused in the horizontal direction, others of the reflecting regions are each formed as an assembly of elliptic paraboloidal reflecting elements that chiefly contribute to the formation of the central area of the luminous intensity distribution pattern, while still another reflecting region is formed as an assembly of bilobate hyperboloidal reflecting elements and, depending on the position of the selected light source (high or low beam) the latter region contributes to the formation of the central area of the luminous intensity distribution pattern of the high beam while contributing to the formation of a cut line that is characteristic of the low beam and that is inclined to the horizontal line of the luminous intensity distribution pattern of the low beam.

Claims

1. A reflector for a headlamp comprising a reflecting surface divided into a plurality of reflecting regions, and at least one of a high-beam light source and a low beam light source positioned in such a way that a central axis thereof extends parallel to the optical axis of said reflecting surface, wherein:

(a) each of said reflecting regions is formed as an assembly of reflecting elements;

(b) each of said reflecting elements has a shape of one of a hyperbolic paraboloid, an elliptic paraboloid and a bilobate hyperboloid depending upon the region of said reflector in which the reflecting element is located, said reflecting elements being fixed to a reference member to form the entire part of said reflecting surface;

(c) ones of said reflecting regions having a high diffusing quality in the luminous intensity pattern of an output beam from said headlamp in the horizontal direction are composed of hyperbolic paraboloidal reflecting elements;

(d) ones of said reflecting regions that contribute to the formation of a central part of said luminous intensity distribution pattern are composed of elliptic paraboloidal reflecting elements; and

(e) a reflecting region contributing to the formation of said central part of said luminous intensity distribution pattern for a high beam while contributing to the formation of a cut line inclined with respect to the horizontal line of said luminous intensity distribution pattern for a low beam is composed of bilobate hyperboloidal reflecting elements.

2. The headlamp of claim 1, wherein said reference member is a paraboloid of revolution.

3. The headlamp of claim 1, wherein each of said segments is positioned in such a way that a line normal to the center of the segment extends along a vector pointing in a direction parallel to the optical axis of said reflecting surface at a point on said reference member to which the segment is attached.

4. The headlamp of claim 1, wherein segments are arranged on said base member in such a way that a line normal to the center of each segment lies parallel to the optical axis of said reflecting surface.

5. The headlamp of claim 1, wherein the direction of a line normal to the center of each elliptic or hyperbolic paraboloidal segment is inclined closer to the optical axis.

6. The headlamp of claim 1, wherein said segments are arranged on said base member in such a manner that continuity between adjacent segments is maintained.

7. The headlamp of claim 1, wherein the light source is of an H₄ halogen C8 type.