Search

EP-3857283-B1 - PROJECTING OPTICAL SYSTEM AND LUMINOUS MODULE FOR A VEHICLE

EP3857283B1EP 3857283 B1EP3857283 B1EP 3857283B1EP-3857283-B1

Inventors

  • ALBOU, PIERRE

Dates

Publication Date
20260513
Application Date
20190926

Claims (13)

  1. Optical projection system (2) of a vehicle lighting module, characterized in that it consists of: - an input optical group (3) comprising at least one lens, capable of receiving light rays from a light source and making them converge, said input optical group (3) consists either of a lens (31) provided with an aspherical input diopter (311) or an aspherical output diopter (312) or of two spherical lenses (32,33); - an intermediate optical group (4) which consists of a first meniscus-type lens (41), directly receiving light rays from the input optical group (3), and a second lens (42) having a convex output diopter (422), the meniscus cavity of the first lens (41) being oriented away from the second lens (42); - an output optical group (5) which consists of a third meniscus-type lens (51), directly receiving light rays from the intermediate optical group (4), and a fourth biconvex or plano-convex lens (52) whose plane diopter is turned toward the third lens (51), the meniscus cavity of the third lens (51) being oriented toward the fourth lens (52).
  2. Optical projection system (2) according to one of the preceding claims, in which the input diopter (311) of the input optical group (3) is convex.
  3. Optical projection system (2) according to one of the preceding claims, in which the input diopter of the second lens (42) is convex, concave or plane, or in which the second lens (42) is a meniscus.
  4. Optical projection system according to one of the preceding claims, in which the input diopter of the second lens (42) has a radius of curvature greater than that of the output diopter (422) of the second lens (42).
  5. Optical projection system (2) according to one of the preceding claims, in which the first lens (41) is made of Flint glass.
  6. Optical projection system (2) according to one of the preceding claims, in which the second lens (42) is made of Crown glass.
  7. Optical projection system (2) according to one of the preceding claims, in which the third lens (51) is made of Flint glass.
  8. Optical projection system (2) according to one of the preceding claims, in which the fourth lens (52) is made of Crown glass.
  9. Optical projection system (2) according to one of the preceding claims, in which the lenses of the intermediate optical group (4) and the output optical group (5) all have spherical diopters.
  10. Automotive lighting module comprising a light source (1) and an optical projection system (2) according to one of the preceding claims and which is configured to produce an output light beam (6), emitted by an output diopter (512) of the output optical group (5), from light from the at least one light source (1) and entering directly into the optical projection system (2).
  11. Module according to the preceding claim, comprising at least one other light source (1) associated with the optical projection system (2) to produce the output light beam (6).
  12. Module according to the preceding claim, in which the light sources (1) are symmetrically spaced around an optical axis (7) of the optical projection system (2).
  13. Module according to one of claims 10 to 12, configured so that the maximum sharpness of the projected beam is located between the middle and two-thirds of a horizontal projection angular sector at the level of the optical axis.

Description

The present invention relates in particular to an optical projection system and a vehicle lighting module. A preferred application is in the automotive industry, for vehicle equipment, particularly for the creation of devices capable of emitting light beams, also known as lighting and/or signaling functions, generally complying with regulations. For example, the invention can enable the production of a segmented light beam, notably for use in front-of-vehicle lighting and/or signaling functions. In particular, the invention can generate a high beam supplement (associated with a basic beam that is wholly or at least mostly projected below a horizontal cutoff line of the type used for the low beam function), with the high beam supplementing the basic beam to complete it above the cutoff line. Advantageously, this high beam supplement is adaptive, activating or deactivating certain parts of the overall projected beam, for example, for anti-glare functions. Vehicle signal and/or lighting devices are lighting systems that include one or more light sources and a lens that closes the light. In simple terms, the light source emits light rays to form a beam that is directed towards the lens, which then transmits the light to the outside of the vehicle. These functions must comply with regulations, particularly regarding light intensity and visibility angles. The lighting modules known to date are designed to emit light fulfilling a lighting function, for example: a dipped beam, mostly directed downwards (there are usually minority parts of the beam which are upwards and which illuminate above the horizon), sometimes still called dipped beam and used in case of presence of other vehicles on the roadway; a road beam without interruption, and characterized by maximum illumination in the axis of the vehicle; a lighting beam for foggy weather, characterized by a flat cutoff and a large illumination width. These functions typically relate to a forward projection. Recently, technologies have been developed to produce a segmented, also called pixelated, beam for adaptive lighting functions, such as those described in UNECE Regulation 123. This is particularly relevant for a "highway supplement" lighting function, which is generally based on multiple lighting units, each containing a light-emitting diode (LED). These LEDs can be individually controlled. The beam, resulting from the different beam segments produced by each LED, is projected using an optical projection system that typically includes one or more lenses. In this description, a segmented beam is defined as a beam whose projection forms an image composed of beam segments, each segment of which can be illuminated independently. A pixelated light source can be used to form these segments. In some cases, particularly in floor-based writing applications using digital micromirror arrays (DMDs), the pixel count is exceptionally high (over 100,000 pixels), and the projection optical system does not require a large numerical aperture. However, the use of high-resolution technologies (over 100,000 pixels) significantly impacts the final cost of the lighting system. To achieve a pixelated, glare-free beam over a wide area, a large numerical aperture is desirable. At the same time, a large aperture must not compromise the quality of the emitted beam, particularly in terms of chromatic aberration. The present invention aims to remedy at least partially this problem. It is known from the document US2003/0112525 A cinematographic projection system whose projection objective comprises a lens assembly forming a so-called double Gauss structure, preceded upstream by a field lens and coupled downstream with a Fraunhofer-type lens doublet. However, this system has a small aperture (1:1.9 or f/1.9) and a significant size (between 100 and 400 mm), resulting in low flux efficiency and mechanical integration difficulties for applications in automotive lighting. The invention aims to provide an efficient and compact optical system for automotive lighting modules. The invention is defined by the claims. Thanks to the lens combination of the invention, the optical system provides a large numerical aperture, i.e., with an aperture number N<1. In particular, the input optical group functions as a field lens, increasing this aperture. Furthermore, the plurality of lenses allows for a precise selection of materials, such as glass, particularly for adjusting chromatic aberration corrections; chromatic aberration control is especially important for adaptive beam applications where the contrast within the beam is high (between illuminated and unilluminated areas). Moreover, this lens combination ensures a compact optical system, advantageously less than 75 mm along the optical axis. Finally, this lens combination has the advantage that the system's exit pupil is located on the outermost diopter and therefore does not require a diaphragm. In a preferred case, the lighting module participates in di