CN115574286B - Free-form surface symbol projection lighting device for vehicle - Google Patents

Free-form surface symbol projection lighting device for vehicle Download PDF

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CN115574286B
CN115574286B CN202211587405.0A CN202211587405A CN115574286B CN 115574286 B CN115574286 B CN 115574286B CN 202211587405 A CN202211587405 A CN 202211587405A CN 115574286 B CN115574286 B CN 115574286B
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free
form surface
lens
illumination
light
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CN115574286A (en
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吴仍茂
沈凡琪
刘鹏
张子钧
胡广银
郑臻荣
李海峰
刘旭
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Zhejiang University ZJU
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21SNON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S43/00Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights
    • F21S43/20Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights characterised by refractors, transparent cover plates, light guides or filters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21SNON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S43/00Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights
    • F21S43/10Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights characterised by the light source
    • F21S43/13Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights characterised by the light source characterised by the type of light source
    • F21S43/14Light emitting diodes [LED]
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21SNON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S43/00Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights
    • F21S43/20Signalling devices specially adapted for vehicle exteriors, e.g. brake lamps, direction indicator lights or reversing lights characterised by refractors, transparent cover plates, light guides or filters
    • F21S43/26Refractors, transparent cover plates, light guides or filters not provided in groups F21S43/235 - F21S43/255
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V5/00Refractors for light sources
    • F21V5/002Refractors for light sources using microoptical elements for redirecting or diffusing light
    • F21V5/004Refractors for light sources using microoptical elements for redirecting or diffusing light using microlenses
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V5/00Refractors for light sources
    • F21V5/007Array of lenses or refractors for a cluster of light sources, e.g. for arrangement of multiple light sources in one plane
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V5/00Refractors for light sources
    • F21V5/008Combination of two or more successive refractors along an optical axis
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0012Optical design, e.g. procedures, algorithms, optimisation routines
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21WINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS
    • F21W2103/00Exterior vehicle lighting devices for signalling purposes
    • F21W2103/60Projection of signs from lighting devices, e.g. symbols or information being projected onto the road
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00Light-generating elements of semiconductor light sources
    • F21Y2115/10Light-emitting diodes [LED]

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  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)

Abstract

The invention discloses a free-form surface symbol projection lighting device for a vehicle, and belongs to the technical field of non-imaging optics. The lighting device is composed of a lighting source and a free-form surface lens group, wherein the free-form surface lens group comprises a beam collimation free-form surface lens and a free-form surface array lens, and the beam collimation free-form surface lens is used for regulating and controlling the intensity and the wave front of a beam. Light rays emitted by the illumination light source are refracted by the beam collimation free-form surface lens and then become parallel light with uniformly distributed energy, and after being deflected by the free-form surface array lens, a preset symbol illumination light spot is formed on the target surface. The vehicular free-form surface symbol projection lighting device has a simple structure, and the free-form surface lens is smooth and continuous and is easy to process; the device can project high-quality complex light spots, and has the advantages of high energy utilization rate, good projection effect, strong practicability and wide application range.

Description

Free-form surface symbol projection lighting device for vehicle
Technical Field
The invention relates to the technical field of non-imaging optics and illumination, in particular to a free-form surface symbol projection illumination device for a vehicle.
Background
Along with the development of science and technology, intelligent automobiles are more and more near to us, and emerging technologies such as intelligent driving, man-machine interaction and the like gradually become an important development direction of intelligent automobiles. Symbol projection, i.e. projecting a specific symbol at an observation position, is one of important directions of man-machine interaction of an automobile, and the existing automobile pattern projection technology is generally realized by blocking light directly through a diaphragm, and the diaphragm realizes pattern projection by preventing propagation of part of light beams, which clearly means that a large amount of light source energy is wasted, and meanwhile, a good projection effect is difficult to achieve by utilizing the light source energy.
CN201822024127.3 proposes an illumination optical device for projection of graphic symbols onto a projection surface, comprising a converging lens and a structure of shaped light arranged downstream of and adjacent to the converging lens in the projection direction, while a coupling-out face of the structure of shaped light has a cross-sectional shape corresponding to the graphic symbol, which device homogenizes the light by means of a TIR (tir= "Total Internal Reflection, total internal reflection") converging lens, after which pattern projection is achieved by means of a darkened pattern projection, which device reduces the light energy utilization, while sharp-boundary and complex pattern projection cannot be achieved.
CN201811224209.0 proposes a car light projection device for reflecting a projection beam by using a MEMS scanning mirror, the device comprising a light source, a beam combining mirror, a shaping cylindrical mirror and a MEMS scanning mirror, wherein the light source generates the projection beam, then the beam combining mirror combines the projection beams in the same direction or different directions into a beam, and then the beam passes through the shaping cylindrical mirror to reach the MEMS scanning mirror, the MEMS scanning mirror reflects the projection beam according to a certain regular rotation, and a projection pattern is projected in a projection area in a scanning manner. The device needs to use the combined action of the multi-lens combination and the MEMS scanning mirror to realize pattern projection, has a complex structure and has higher requirement on the scanning precision of the scanning device.
In order to further improve the application of pattern projection in car lamp illumination and solve the problem of man-machine interaction in intelligent automobiles, it is very necessary to provide a symbol projection device with simple structure, high efficiency, energy saving and good projection effect. The optical free curved surface is an optical curved surface without axisymmetric or translational symmetric, the flexible surface-shaped structure of the optical free curved surface can break through the traditional optical system concept to create a brand-new structural form, the system structure can be greatly simplified while the system performance is effectively improved, the number of optical elements is reduced, a light and small-sized light beam regulating system with high performance and new functions can be realized, and the optical free curved surface has important application value in the tip national defense and civil fields such as efficient energy-saving illumination, laser beam shaping and the like. The free-form surface has great application potential in the aspect of pattern projection by virtue of the advantage of a flexible surface structure, the regulation and control principle means that after the influence of Fresnel reflection is ignored, all light rays are regulated and controlled to a target projection area, the free-form surface projection device has great application value in the aspect of improving the energy utilization rate of a projection system, and meanwhile, the free-form surface projection device is simple in structure and convenient to install and adjust in use.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a free-form surface symbol projection lighting device for a vehicle. The technical scheme of the invention is as follows:
the invention provides a vehicular free-form surface symbol projection lighting device, which comprises a lighting source and a free-form surface lens group, wherein the free-form surface lens group comprises a beam collimation free-form surface lens and a free-form surface array lens which are sequentially arranged along a light path; the beam collimation free-form surface lens comprises an incident surface and an emergent surface, wherein the incident surface and the emergent surface are free-form surfaces and have no rotational symmetry; the free-form surface array lens comprises an incident surface and an emergent surface, wherein the incident surface is a plane, and the emergent surface is a free-form surface and has no rotational symmetry; the light beam collimation free-form surface lens is used for light beam collimation, deflects the light beam emitted by the illumination light source into parallel light with uniform illumination intensity distribution, and vertically irradiates the incident surface of the free-form surface array lens; the parallel light is deflected by the free-form surface array lens to generate a preset symbol illumination spot on the target illumination surface;
the emergent surface of the free-form surface array lens consists of a plurality of completely identical free-form surface units which are arranged in a periodic array; the free-form surface unit shapes the parallel light beams with uniform energy distribution into illumination distribution of a target pattern, the optical axis of the free-form surface unit is parallel to the optical axis of the illumination light source, and the incident light beam of the incidence surface of the free-form surface array lens does not have deflection effect.
Further, the free-form surface lens group is designed according to the following steps:
1) The method comprises the steps of (1) carrying out initial design on a beam collimation free-form surface lens and a free-form surface array lens according to initial design parameters;
2) Designing a beam collimation free-form surface lens according to the Snell's law, the energy conservation law and the aplanatic principle, and shaping an outgoing beam of an illumination light source into parallel light with uniform light intensity distribution, wherein the optical axis of the beam collimation free-form surface lens is coincident with the optical axis of the illumination light source;
3) Designing a free-form surface array lens according to the law of conservation of energy and the Snell's law;
4) Modeling the beam collimation free-form surface lens and the free-form surface array lens to obtain the free-form surface lens group.
Further, the design of the free-form surface array lens comprises the following steps:
3.1 The size of the free-form surface array lens is k, wherein the lens comprises m x m identical free-form surface lens units, m is an integer greater than 1, and the caliber of each designed free-form surface lens unit is k/m;
3.2 Establishing an energy conservation relation:
Figure 970837DEST_PATH_IMAGE001
wherein ,I(x,y)for the intensity distribution of the light source, whereI(x,y)Is a uniform illumination beam distributed in a square shape, the aperture size of the beam is k/m,E(t x ,t y )for the illumination distribution of the target illumination area on the target illumination surface, i.e. the final target illumination distribution, J (T) is Jacobi matrix of the position vector T,
Figure 419136DEST_PATH_IMAGE002
3.3 Simplifying the above equation to get the equation:
Figure 730031DEST_PATH_IMAGE003
wherein z xx z yy Coordinates of P points respectivelyzWith respect toxAndyis used for the first partial derivative of (c),z xy the coordinate z for the P point is aboutxAndysecond order mixed partial derivative of (2), coefficientB i Represented asz x z y zx and yWhereinB 1 Is thatz xx z yy -z xy 2 The coefficient equation of the term,B 2 is thatz xx The coefficient equation of the term,B 3 is thatz yy The coefficient equation of the term,B 4 is thatz xy The coefficient equation of the term,B 5 as a constant term equation, the internal ray of the incident beam should satisfy the energy transmission equation;
3.4 A boundary condition is established;
3.5 And (3) solving the energy transmission equation and the boundary condition simultaneously to obtain a group of discrete data points, and performing surface fitting on the group of data points to obtain the surface shape of the required free-form surface unit.
Compared with the prior art, the invention has the following beneficial effects:
1) The invention adopts the free-form surface light beam regulation and control technology, and solves the technical problems that fine pattern projection and fuzzy pattern boundary are difficult to realize in the prior art, thereby obtaining a fine and complex projection pattern with sharp boundary.
2) The invention solves the problem of light beam energy waste in the prior art, can distribute all incident light energy into the target pattern under the condition of neglecting Fresnel reflection, and has high energy utilization rate.
3) The invention adopts the free-form surface array lens as the pattern projection lens, and solves the problems of high requirement on system alignment precision, difficult adjustment and the like in the prior art.
4) The invention adopts the free-form surface lens as the light beam collimating lens, and overcomes the requirement of the prior art on the rotational symmetry of the light source.
Drawings
FIG. 1 is a schematic view of the light path of the free-form surface symbol projection lighting device for vehicles.
Fig. 2 is a schematic diagram of the structure of the beam collimating freeform lens of the present invention.
FIG. 3 is a schematic view of the free-form surface array lens according to the present invention.
FIG. 4 is a schematic view of a free-form lens assembly according to the present invention.
Fig. 5 is a graph of beam-collimating freeform lens ray tracing results.
FIG. 6 is a graph of the ray tracing results of a free-form lens assembly.
In the figure, 1-an illumination source; 2-beam collimating freeform lenses; 3-free-form surface array lens; 4-free-form surface lens group; 5-a first entrance face; 6-a first exit face; 7-a second entrance face; 8-a second exit face.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described below with reference to the accompanying drawings, and the present invention is mainly composed of a free-form surface lens group, wherein the free-form surface lens group includes a free-form surface lens for beam collimation and homogenization and a free-form surface array lens for generating pattern projection.
1-4, the embodiment of the invention provides a free-form surface symbol projection lighting device for a vehicle; the projection device comprises an illumination source 1 and a free-form surface lens group 4, wherein the free-form surface lens group 4 comprises a beam collimation free-form surface lens 2 and a free-form surface array lens 3; the light beam from the illumination light source 1 is deflected by the light beam collimation free-form surface lens 2 to become parallel light with uniform illumination intensity distribution, and the parallel light is deflected by the free-form surface array lens 3 to generate directional illumination distribution on the target illumination surface, as shown in figure 1.
The beam collimating free-form surface lens 2 of the present embodiment includes a first incident surface 5 and a first exit surface 6, wherein the first incident surface 5 and the first exit surface 6 are free-form surfaces, and have no rotational symmetry. The beam collimating free-form surface lens 2 is used for beam collimation, deflects the beam emitted by the illumination light source into parallel light with uniform illumination intensity distribution, and vertically irradiates the incidence surface of the free-form surface array lens 3.
The free-form surface array lens 3 of the present embodiment includes a second incident surface 7 and a second exit surface 8, wherein the second incident surface 7 is a plane, and the second exit surface 8 is a free-form surface and has no rotational symmetry; the parallel light is deflected by the free-form surface array lens 3 to generate a preset symbol illumination spot on the target illumination surface; the emergent surface of the free-form surface array lens consists of a plurality of completely identical free-form surface units which are arranged in a periodic array; the free-form surface unit shapes the parallel light beams with uniform energy distribution into illumination distribution of a target pattern, the optical axis of the free-form surface unit is parallel to the optical axis of the illumination light source, and the incident light beam of the incidence surface of the free-form surface array lens does not have deflection effect.
In the present embodiment, the design method of the free-form surface lens group 4 is as follows:
(1) Design of beam collimation free-form surface lens 2
Designing a beam collimation free-form surface lens and a free-form surface array lens according to initial design parameters; and designing a beam collimation free-form surface lens according to the Snell's law, the energy conservation law and the aplanatic principle, and shaping the emergent beam of the illumination light source into parallel light with uniform light intensity distribution, wherein the optical axis of the beam collimation free-form surface lens is coincident with the optical axis of the illumination light source.
(2) Design of free-form surface array lens 3
According to the law of conservation of energy and the law of Snell, designing a free-form surface array lens, wherein the emergent surface of the free-form surface array lens consists of a plurality of free-form surface units which are arranged in an array; the free-form surface unit shapes the parallel light beams with uniform energy distribution into illumination distribution of a target pattern, the optical axis of the free-form surface unit is parallel to the optical axis of the illumination light source, the incident surface of the free-form surface array lens is a plane, and the incidence light beams are not deflected.
(3) Modeling the beam collimation free-form surface lens and the free-form surface array lens to obtain the free-form surface lens group.
Examples: the light source is a white light LED with lambertian light intensity distribution, the light intensity distribution satisfies I (phi) =cos phi, the height of the lighting device is 10mm, namely, the distance from the incident LED light source to the emergent surface of the optical system is 10mm, the projection distance is 500mm, namely, the distance from the light source to the target projection surface is 500mm, the size of the projection pattern is 300 x 300mm, and the illumination ratio of the pattern to the background is 2.5:1, in this embodiment, the projection pattern is a symbol "ZJ1" letter, and meanwhile, the projection pattern can be flexible and changeable according to different application requirements. The refractive index of the material 1.4936 used for the character head curved surface lens group is 1.4936, the surrounding medium of the lens is air, the total length of the free curved surface lens group is smaller than 10mm, and the caliber size is 4mm.
The design of the beam collimating free-form surface lens 2 of this embodiment is as follows:
the method comprises the steps of designing a free-form surface lens for beam collimation according to the Snell's law, the energy conservation law and the aplanatic principle, and shaping an outgoing beam of an illumination light source into parallel light with uniform light intensity distribution, wherein the optical axis of the beam collimation free-form surface lens coincides with the optical axis of the illumination light source;
establishing an energy conservation relation:
Figure 905667DEST_PATH_IMAGE004
wherein ,
Figure 251197DEST_PATH_IMAGE005
for the intensity distribution of the illumination source,
Figure 604818DEST_PATH_IMAGE006
for a target illuminance distribution on the entrance face of the self-curved array lens, J (T) is Jacobi matrix of position vector T,
Figure 668589DEST_PATH_IMAGE007
is the azimuth angle in the polar coordinate system,
Figure 149380DEST_PATH_IMAGE008
is the polar angle;
Figure 349417DEST_PATH_IMAGE009
Figure 873940DEST_PATH_IMAGE010
, wherein
Figure 362690DEST_PATH_IMAGE011
The maximum divergence angle of the beam entering the beam collimating freeform lens.
Establishing an aplanatic principle relation: opl= |op|+n|pq|+|qt|, where OPL is the optical path of a ray from the light source to a wavefront, |op| is the distance between the ray from the light source to the free-form surface entrance surface, |pq| is the distance between the intersection of the ray on the free-form surface entrance surface and the exit surface, |qt| is the distance between the intersection of the exit surface and a wavefront, n is the refractive index of the lens material, n= 1.49386.
The energy conservation relational expression and the equal optical path principle relational expression are combined to obtain the following second-order nonlinear partial differential equation
Figure 630860DEST_PATH_IMAGE012
wherein ,ris the light beam in the beamThe distance between the landing points on the entrance surface and the exit surface of the straight freeform lens,
Figure 934671DEST_PATH_IMAGE007
is the azimuth angle in the polar coordinate system,
Figure 895674DEST_PATH_IMAGE008
is the polar angle of the light source,
Figure 668458DEST_PATH_IMAGE013
Figure 474740DEST_PATH_IMAGE014
respectively arer At the position of
Figure 665681DEST_PATH_IMAGE007
And
Figure 532006DEST_PATH_IMAGE008
the first partial derivative of the direction is used,
Figure 792086DEST_PATH_IMAGE015
Figure 605321DEST_PATH_IMAGE016
respectively arerAt the position of
Figure 634457DEST_PATH_IMAGE007
And
Figure 186530DEST_PATH_IMAGE008
the second partial derivative of the direction,
Figure 668327DEST_PATH_IMAGE017
is thatrAt the position of
Figure 347570DEST_PATH_IMAGE007
And
Figure 231212DEST_PATH_IMAGE008
the second order mixed partial derivative of the two directions,A i is that
Figure 455651DEST_PATH_IMAGE013
Figure 424744DEST_PATH_IMAGE014
r
Figure 376520DEST_PATH_IMAGE007
and
Figure 583510DEST_PATH_IMAGE008
I=1,..5, whereinA 1 Is that
Figure 228118DEST_PATH_IMAGE018
The coefficient equation of the term,A 2 is that
Figure 933775DEST_PATH_IMAGE016
The coefficient equation of the term,A 3 is that
Figure 954821DEST_PATH_IMAGE015
The coefficient equation of the term,A 4 is that
Figure 547476DEST_PATH_IMAGE017
The coefficient equation of the term,A 5 is a constant term equation.
Establishing boundary conditions:
Figure 362985DEST_PATH_IMAGE019
wherein ,
Figure 57403DEST_PATH_IMAGE020
indicating the extent of the beam incident on the free-form surface,
Figure 616560DEST_PATH_IMAGE021
representing the illuminated area on the entrance face of the self-curved array lens,
Figure 329301DEST_PATH_IMAGE022
and
Figure 253395DEST_PATH_IMAGE023
respectively are areas
Figure 684376DEST_PATH_IMAGE024
And
Figure 54350DEST_PATH_IMAGE021
is defined by the boundary of (a).
And solving the second-order nonlinear partial differential equation and the boundary condition simultaneously by utilizing a differential substitution differential method and a Newton iteration method to obtain a group of discrete data points, and performing surface fitting on the group of data points to obtain the surface type of the required free-form surface unit.
The design of the free-form surface array lens 3 of this embodiment is as follows:
designing a free-form surface array lens according to an energy conservation law and a Snell's law, wherein the free-form surface array lens consists of 16 identical free-form surface units which are arrayed along two mutually perpendicular directions; the free-form surface array module comprises a free-form surface array lens, a target pattern illumination distribution unit, a free-form surface array module and a light source, wherein the free-form surface array module is used for forming a parallel light beam with uniform energy distribution into the target pattern illumination distribution, the optical axis of the free-form surface unit is parallel to the optical axis of the illumination light source, the incident surface of the free-form surface array lens is a plane, the incident light beam is not deflected, and the emergent surface is a free-form surface;
establishing an energy conservation relation, wherein under the condition of not considering energy loss, any one of the beamlets emitted by the light source is deflected by the free-form surface lens, and all energy of the beamlets is transmitted to a target illumination area on an illumination surface, namely the deflection of the free-form surface to the beamlets satisfies the following energy relation
Figure 887177DEST_PATH_IMAGE001
, wherein ,I(x,y)is the intensity distribution of the light source;E(t x ,t y )for illumination of a target illuminated area on a target illuminated surfaceThe distribution, herein referred to as "ZJU" letter symbols, J (T) is the Jacobi matrix of the position vector T,
Figure 44489DEST_PATH_IMAGE025
simplifying the above equation further yields the equation:
Figure 962766DEST_PATH_IMAGE003
wherein z xx z yy Coordinates of P points respectivelyzWith respect toxAndyis used for the first partial derivative of (c),z xy the coordinate z for the P point is aboutxAndysecond order mixed partial derivative of (2), coefficientB i Represented asz x z y zx and yWhereinB 1 Is thatz xx z yy -z xy 2 The coefficient equation of the term,B 2 is thatz xx The coefficient equation of the term,B 3 is thatz yy The coefficient equation of the term,B 4 is thatz xy The coefficient equation of the term,B 5 as a constant term equation, the internal rays of the incident beam should satisfy the energy transfer equation described above.
The free-form surface satisfies the energy transmission equation and ensures that boundary rays of the light beam are deflected by the free-form surface and then enter the boundary of the target illumination area, namely the following boundary conditions are satisfied
Figure 614459DEST_PATH_IMAGE026
wherein ,
Figure 36213DEST_PATH_IMAGE027
representing the extent of the outgoing beam of a beam-collimating freeform lens, i.eThe extent of the beam incident on the free-form surface array lens,
Figure 364426DEST_PATH_IMAGE028
representing the illuminated area on the illuminated surface of the object,
Figure 504420DEST_PATH_IMAGE029
and
Figure 412333DEST_PATH_IMAGE030
respectively are areas
Figure 203441DEST_PATH_IMAGE027
And
Figure 702555DEST_PATH_IMAGE028
is defined by the boundary of (a).
And solving the energy transmission equation and the boundary condition simultaneously to obtain a group of discrete data points, and performing surface fitting on the group of data points to obtain the required surface shape of the free-form surface unit.
The collimating free-form surface lens and the free-form surface array lens are modeled to obtain a free-form surface lens projection module, see fig. 2, fig. 3 and fig. 4, wherein fig. 2 is the free-form surface lens 2 for beam collimation and homogenization, fig. 3 is the free-form surface array lens 3 for generating symbol projection, and fig. 4 is the integral model of the vehicular free-form surface symbol projection lighting device. The first incident surface 5 and the first emergent surface 6 of the beam collimation free-form surface lens 2 are free-form surfaces and have no rotational symmetry; the second incident surface 7 of the free-form surface array lens 3 is a plane, the second emergent surface 8 is a free-form surface, and is formed by arranging 4*4 free-form surface unit arrays, and the emergent surface has no rotational symmetry; the beam collimation free-form surface lens 2 deflects the beam emitted by the illumination light source into parallel light with uniform illumination intensity distribution, and vertically irradiates the incidence surface of the free-form surface array lens 3, and the parallel light is deflected by the free-form surface array lens 3 to generate a preset ZJU symbol illumination spot on the target illumination surface.
The light ray tracing is carried out on the collimation free-form surface lens, the illuminance distribution of the emergent light ray at any plane is shown in figure 5, and the light beam with lambertian distribution is shaped into uniform square light spots and parallel collimation light beams after passing through the collimation free-form surface lens 2 according to the figure 5. The free-form surface lens group model is traced with light, an illuminance distribution diagram is obtained on a target illumination surface, the illuminance distribution diagram is shown in figure 6, and the incident light beam is changed into pattern distribution with a ZJU letter style on the target surface after being shaped by the symbol projection illumination device provided by the invention, which is shown in figure 6. The illuminance distribution diagram clearly shows that the free-form surface symbol projection lighting device for the vehicle provided by the invention realizes the target lighting requirement, and effectively simulates uniform lighting spots with clear boundaries of natural light irradiation.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit of the invention.

Claims (7)

1. The free-form surface symbol projection lighting device for the vehicle is characterized by comprising an illumination light source and a free-form surface lens group, wherein the free-form surface lens group comprises a beam collimation free-form surface lens and a free-form surface array lens which are sequentially arranged along an optical path; the beam collimation free-form surface lens comprises an incident surface and an emergent surface, wherein the incident surface and the emergent surface are free-form surfaces and have no rotational symmetry; the free-form surface array lens comprises an incident surface and an emergent surface, wherein the incident surface is a plane, and the emergent surface is a free-form surface and has no rotational symmetry; the light beam collimation free-form surface lens is used for light beam collimation, deflects the light beam emitted by the illumination light source into parallel light with uniform illumination intensity distribution, and vertically irradiates the incident surface of the free-form surface array lens; the parallel light is deflected by the free-form surface array lens to generate a preset symbol illumination spot on the target illumination surface;
the emergent surface of the free-form surface array lens consists of a plurality of completely identical free-form surface units which are arranged in a periodic array; the free-form surface unit shapes the parallel light beams with uniform energy distribution into illumination distribution of a target pattern, the optical axis of the free-form surface unit is parallel to the optical axis of the illumination light source, and the incident light beam of the incidence surface of the free-form surface array lens does not have deflection effect;
the free-form surface lens group is designed according to the following steps:
1) The method comprises the steps of (1) carrying out initial design on a beam collimation free-form surface lens and a free-form surface array lens according to initial design parameters;
2) Designing a beam collimation free-form surface lens according to the Snell's law, the energy conservation law and the aplanatic principle, and shaping an outgoing beam of an illumination light source into parallel light with uniform light intensity distribution, wherein the optical axis of the beam collimation free-form surface lens is coincident with the optical axis of the illumination light source;
the step 2) comprises the following steps:
2.1 Establishing an energy conservation relation:
Figure QLYQS_1
wherein ,
Figure QLYQS_2
for the intensity distribution of the illumination source +.>
Figure QLYQS_3
J (T) is Jacobi matrix of position vector T for target illuminance distribution on incidence plane of self-curved array lens>
Figure QLYQS_4
Is the azimuth angle in the polar coordinate system, +.>
Figure QLYQS_5
Is the polar angle; />
Figure QLYQS_6
Figure QLYQS_7
, wherein />
Figure QLYQS_8
A maximum divergence angle of a light beam incident on the beam collimating freeform lens;
2.2 Establishing an aplanatic principle relation;
2.3 The simultaneous energy conservation relation and the aplanatic principle relation are used for obtaining the following second-order nonlinear partial differential equation:
Figure QLYQS_9
wherein ,ris the distance between the falling points of the light rays on the incident surface and the emergent surface of the beam collimation free-form surface lens,
Figure QLYQS_16
is the azimuth angle in the polar coordinate system, +.>
Figure QLYQS_10
Is polar angle->
Figure QLYQS_14
、/>
Figure QLYQS_12
Respectively arer At->
Figure QLYQS_17
and />
Figure QLYQS_19
First order partial derivative of direction,/->
Figure QLYQS_21
、/>
Figure QLYQS_28
Respectively arerAt->
Figure QLYQS_29
and />
Figure QLYQS_13
Second partial derivative of direction,/->
Figure QLYQS_26
Is thatrAt->
Figure QLYQS_20
and />
Figure QLYQS_22
The second order mixed partial derivative of the two directions,A i is->
Figure QLYQS_25
、/>
Figure QLYQS_27
r、/>
Figure QLYQS_18
and />
Figure QLYQS_23
I=1,..5, whereinA 1 Is->
Figure QLYQS_24
The coefficient equation of the term,A 2 is->
Figure QLYQS_30
The coefficient equation of the term,A 3 is->
Figure QLYQS_11
The coefficient equation of the term,A 4 is->
Figure QLYQS_15
The coefficient equation of the term,A 5 is a constant term equation;
2.4 A boundary condition is established;
2.5 Using a differential substitution differential method and a Newton iteration method to solve the second-order nonlinear partial differential equation and the boundary condition simultaneously to obtain a group of discrete data points, and performing surface fitting on the group of data points to obtain the surface type of the required beam collimation free-form surface lens;
3) Designing a free-form surface array lens according to the law of conservation of energy and the Snell's law;
4) Modeling the beam collimation free-form surface lens and the free-form surface array lens to obtain the free-form surface lens group.
2. The free-form surface symbol projection lighting device as claimed in claim 1, wherein the aplanatic principle relation in the step 2.2) is as follows:
OPL=|OP|+n|PQ|+|QT|
wherein OPL is the optical path of a light ray from a light source to a wavefront, OP is the distance between the light ray from the illumination light source to the incidence plane of the beam collimating freeform lens, PQ is the distance between the intersection of the light ray on the incidence plane of the beam collimating freeform lens and the exit plane, QT is the distance between the intersection of the light ray on the exit plane and the wavefront, and n is the refractive index of the lens material.
3. The free-form surface symbol projection lighting device as set forth in claim 1, wherein the boundary conditions in said step 2.4) are:
Figure QLYQS_31
wherein ,
Figure QLYQS_32
representing the range of light incident on a free-form surfaceEnclose (or) the>
Figure QLYQS_33
Representing the illumination area on the entrance face of the lens from a curved array,/->
Figure QLYQS_34
and />
Figure QLYQS_35
Region +.>
Figure QLYQS_36
and />
Figure QLYQS_37
Is defined by the boundary of (a).
4. The vehicular freeform surface symbol projection lighting device as claimed in claim 1, wherein the method for designing the freeform surface array lens comprises the steps of:
3.1 The size of the free-form surface array lens is k, wherein the lens comprises m x m identical free-form surface lens units, m is an integer greater than 1, and the caliber of each designed free-form surface lens unit is k/m;
3.2 Establishing an energy conservation relation:
Figure QLYQS_38
wherein ,I(x,y)for the intensity distribution of the light source, whereI(x,y)Is a uniform illumination beam distributed in a square shape, the aperture size of the beam is k/m,E(t x ,t y )for the illumination distribution of the target illumination area on the target illumination surface, i.e. the final target illumination distribution, J (T) is Jacobi matrix of the position vector T,
Figure QLYQS_39
3.3 Simplifying the above equation to get the equation:
Figure QLYQS_40
wherein z xx z yy Coordinates of P points respectivelyzWith respect toxAndyis used for the first partial derivative of (c),z xy the coordinate z for the P point is aboutxAndysecond order mixed partial derivative of (2), coefficientB i Represented asz x z y zx and yWhereinB 1 Is thatz xx z yy -z xy 2 The coefficient equation of the term,B 2 is thatz xx The coefficient equation of the term,B 3 is thatz yy The coefficient equation of the term,B 4 is thatz xy The coefficient equation of the term,B 5 as a constant term equation, the internal ray of the incident beam should satisfy the energy transmission equation;
3.4 A boundary condition is established;
3.5 And (3) solving the energy transmission equation and the boundary condition simultaneously to obtain a group of discrete data points, and performing surface fitting on the group of data points to obtain the surface shape of the required free-form surface unit.
5. The vehicular freeform surface symbol projection lighting device of claim 4 wherein the target illuminance distribution in step 3.2) is a uniform distribution, a pattern distribution, or other illuminance distribution specified by the user.
6. The vehicular freeform surface symbol projection lighting device as claimed in claim 4, wherein the boundary conditions in step 3.4 are:
Figure QLYQS_41
wherein ,
Figure QLYQS_42
represents the extent of the outgoing beam of the beam collimating freeform lens, i.e. the extent of the beam incident on the freeform array lens, +.>
Figure QLYQS_43
Representing the illuminated area on the illuminated surface of the object, +.>
Figure QLYQS_44
and />
Figure QLYQS_45
Region +.>
Figure QLYQS_46
and />
Figure QLYQS_47
Is defined by the boundary of (a).
7. The vehicular freeform surface symbol projection lighting device as in claim 1 wherein the lighting source is a white LED light source or a laser diode light source.
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