CS253224B1 - Headlamp for motor vehicles - Google Patents

Abstract

The solution concerns the improvement of the luminous intensity and the reduction of the dimensions of the headlamp, especially for motor vehicles, whose reflector has a reflecting surface in the shape of a continuous or segmented rotational ellipsoid, with a light source in the first focus and with a linear aperture with a horizontal cutting edge in the second focus in the horizontal or below it. Behind the aperture is placed a horizontally plano-convex refractor of cylindrical shape. The solution is applicable in road transport, especially on passenger cars and trucks.

Description

The invention relates to a headlamp, especially for motor vehicles, which is composed of an ellipsoidal reflector, a linear aperture with a horizontal cutting edge, a light source and a horizontally placed cylindrical refractor. The purpose of the invention is to increase the luminous efficiency of the headlamp, reduce its dimensions and improve the spatial distribution of luminosity in the light beam.

Common types of headlights use a parabolic reflector to increase directional light output, which has a relatively large output dimension at a given angle of incidence. This results in a deterioration in the possibilities of integrating such a headlight into the vehicle body due to its large width and especially height, an increase in its weight, and a relatively low degree of heredity and normalization of headlight parts on various, aerodynamically differently shaped vehicles.

These shortcomings are eliminated in the headlamp according to the invention, whose ellipsoidal reflector directs the light flux from the light source into a convergent beam, which is then transformed by a horizontal cylindrical refractor into a beam of vertically approximately parallel rays. A linear aperture with a horizontally guided cutting edge is placed near the common focal plane of the reflector and the refractor. The resulting brightness contrast is then projected by the refractor onto the road by imaging the focal plane. Thus, the desired light-dark interface is created, the luminous efficiency and performance of the headlamp are increased due to the increase in the angle of incidence of the ellipsoidal reflector, the uniformity of the spatial distribution of the luminance in the light beam is improved, as well as the sharpness of the light-dark interface when a lower level of dazzling luminance is achieved above this interface. The higher integration effect of the ellipsoidal reflector is reflected in the reduction of the angle of tangents of the reflecting surface in tangential sections and thus in the reduction of its output dimensions. Reducing the height of the headlight then allows the front part of the body to be designed low and wedge-shaped. This will contribute to reducing the vehicle's drag coefficient, while even a significant vertical tilt of the cover glass will not cause the characteristic aberrations of the light beam caused by the tilt of the cover glasses of conventional headlights.

Detailed characteristics of the invention will be further explained with the help of the attached illustrations, where Fig. 1 shows the optical system of the headlamp, Fig. 2 shows a vertical and Fig. 3 a horizontal section of the headlamp, Fig. 4 presents an example of the shape solution of an ellipsoidal homofocal reflector in front view and Fig. 5 shows a horizontal section of this reflector.

Fig. 1 shows a headlamp, the light source £ of which has a transverse dimension is located in the first focus of the reflector 1. The reflecting surface of the reflector \1 is in the shape of a rotating ellipsoid placed with its vertex at the origin of the coordinate system of axes x, y, z, where the x axis is the axis of rotation of the ellipsoid and the headlamp axis. The forming profile of the ellipsoid is given by

P 2

Y = 2px - - x ² (1) where p - parameter of the ellipsoid and - major semi-axis of the ellipsoid or + ε . cosV (2) where p- polar conductor of the ellipsoid ε- numerical eccentricity of the ellipsoid (ε < 1)

The focus is at a distance x^ from the vertex of the ellipsoid, which is

(3) and the semi-major axis a is given by (4) x

CS 253 224 Bl (5) where e - linear eccentricity of the ellipsoid e = e .a

At a distance x ₂ ^x 2 ^{= x} o ^{+ 2,e (6)} the second focus F ₂ of the reflector 2» is in which, or behind which at a distance x _c ^x c^ ^x 2 < ⁷ >

A diaphragm 2 with a linear and horizontally guided cutting edge 5 is placed, which is located in the horizontal plane of the light meter (y = 0) or below it.

Behind the aperture 2, a plano-convex refractor 2 of cylindrical type with a horizontally positioned axis 2 is placed, with its flat wall E on the side of the aperture 2.

In Fig. 2, the vertical version is shown, where the reflector has a 2-fold convergence angle, where the horizontal section B-B is the section A-A, and in Fig.

has a different vertical angle of incidence φ _? , dimension D _v and angle of convergence ^{h 2} ·Ρ„ (8) i + . .cos ev,h <pv,ha

-___._ cv,h' ^s ^ ⁿ <pv,h cv,h (pv,h ' ! ₊ .cos ev,h <pv,h

In order to increase the luminous efficiency, there is a reflector of 2 meters (p _v = P _h = p) and of the same numerical eccentricity (e _v = is provided with an exit opening protruding in a horizontal section of continuous shape of the same para= c) in both sections AA, BB and BB with respect to the vertical section AA, so that ν'“ν''h' (10)

A reflector of 2° axial power da and refractive index n is alternatively provided on its flat wall E with strip cylindrical lenses £ of width t and radius r, and the ratio t/2r is (0.5 - 40) sin (t/2r)' = 4 arctan (ε ) - π/2 + 2 arctan arcsin (t/2r) c π/2 (11) ^p v where - numerical cexcentricity of the ellipse in the vertical section AA through the reflector 2

P _v - ellipse parameter in vertical section AA by reflector 2

The forming profile T_ of the refractor 2 ^is circular with radius R and center C, or this circle is an osculating circle at the vertex y ₂ and the forming profile T_ is raised relative to it towards the edges of the refractor 2 so that its normal N is inclined relative to the x axis of the headlamp at an angle Θ, where sin i7

Θ = arctg -(12) cos ij - n where ij - angle of refraction on the surface of refractor 2

CA 253 224 Bl

1Γ - acesin/n \sin (arctg ——) / ^X F where h - drop height of refractor 2

Xp - distance of the focal plane of the refractor 2 _in _ nR - (n - 1).d F (η - 1) ,n (13) (14)

The reflector 2 is mounted in the light meter in such a way that its flat wall E is at a distance x_ and greater from the second focus F ₂ of the reflector 1.

— —r

In addition to the continuous type of reflector 1_, a reflector 1 of homofocal shape according to Fig. 4, 5 can be applied in the headlamp, in which the reflecting surface is tangentially divided into several ellipsoidal segments 8^, £, IQ, whose parameter increases and the numerical eccentricity ε- decreases from segment £ in the vertical section C-C of the reflector 1_ to segment 10 in the horizontal section D-D. The length a^ of the major semi-axis forming the ellipse of the ith ellipsoidal segment is

- Pv ^and v>

1/2 (15) where p^ - parameter of the ith ellipsoidal segment 2 of reflector 2 a„ - length of the major semi-axis of ellipsoidal segment 2 ⁱⁿ vertical section through reflector 2 P _v - parameter of ellipsoidal segment 2 ⁱⁿ vertical section CC through reflector 2

The numerical eccentricity r, of the i-th ellipsoidal segment 2 of the reflector 2 is· <2 = ⁽¹ - p _i /a _i ) ^1/2 (16) and the forming profile of the i-th ellipsoidal segment 9 is, in section along the x-axis of the headlamp, of a continuous shape 11, or of a stepped shape 12, composed of several forming ellipses with the same linear eccentricity e.

^e i ^{= e} i' ^and i ⁼ k° ⁿ st. (17) and is radially connected by conductors 1_3, whose angle β is equal to or smaller than the angle of engagement <P _z at the point Q of penetration

P < _φζ (18)

The advantage of this solution is in particular the increase in the brightness gradient above the cutting edge 2 of the aperture 2, which is reflected in the increase in luminosity in the space adjacent to the interface between light and darkness and thus also in the increase in the photometric visibility distance of the light beam according to the invention.

Claims (5)

SUBJECT OF THE INVENTION Headlamp, in particular for motor vehicles, comprising a concave reflector, an aperture, a refractor and a light source, characterized in that the light source (4) is arranged in a first focus (Fp of the reflector (1), the reflecting surface of which is a symmetry identical to the optical axis (x) of the headlamp, with the second focus (F ^) of the reflector (1) having a linear aperture (2) with a horizontal cutting edge (5) lying in and / or below the horizontal (y = 0) , and the refractor (3), located behind the orifice (2), is of cylindrical type with a horizontally mounted axis (q) and a flat-shaped forming profile (7). Headlamp according to claim 1, characterized in that the flat wall (E) of the refractor (3) is provided with vertical strip cylindrical lenses (6) of width (t) and radius (r) such that the ratio (t / 2r) is CS 253 224 Bl (0,5 - 40) .arcsin (t / 2y) = 4 arctg (e _y ) - π / 2 + 2 arctg ~ - arcsin (t / 2y) <n / 2 (1) ^ where : ε _ν = numerical exeentricity of ellipse in vertical section through reflector (1) P _v = ellipse parameter in vertical section through reflector (1) s = transverse dimension of light source (4) Headlamp according to Claims 1 and 2, characterized in that the refractor (3) of axial force (d), the radius (R) of the oscillating circle at the apex ( ₂ ) of the forming profile (7) and the refractive index (n) is from the second focus (F _n ) of the reflector (1) with its flat wall (E) at a distance (x ") at a distance Z r (Xp) and less, where a forming profile (7) of the refractor (3) is circular with radius (R), or is raised relative to this circle so that its normal (N) is inclined for falling height (h) relative to the headlamp axis (x) at an angle (Θ) sin iΘ - arctg --— (3) cos i '- n where: ij - refraction angle on the first surface of the refractor (3) ίΓ - arcsin / n \ sin (arctg - -) i (4) ^{1 x} p 4. A headlamp according to claim 1, 2 and 3, characterized in that the reflector (1) has a continuous reflecting surface of the same parameter (p) and a numerical eccentricity (¢) limited at the output such that the angle of projection (φ) D) and the convergence angle (a) is smaller in the vertical section (AA) than in the section (BB) of the horizontal four D,, <p _h (5) Headlight according to Claims 1, 2 and 3, characterized in that the reflector (1) is of homofocal shape, where the reflecting surface is divided tangentially into ellipsoidal segments (8, 9, 10), their parameter (p ^) increases and the numerical exeentricity ( ε ^) decreases from segment (8) in vertical section (CC) by reflector (1) to segment (10) in horizontal section (DD) by reflector (1) and length of main half axis (a ^) of ith elliptical segment (9) the reflector (1) + <- p .a) ^r v v ' 1/2 (6) where: p ^ - parameter, i-th segment (9) of reflector (1), and _v - length of main half-axis of ellipse of segment (8) in vertical section by CC reflector (1), P _v - ellipse parameter of the segment (8) in the vertical section (CC) by the reflector (1) and the numerical exeentricity (e ^) of the i-ellipsoidal segment (9) is (1 (7) wherein the forming profile of the i-ellipsoid segment (9) is (x) a headlamp of continuous shape (11), or · of a stepped shape (12), composed of several ellipses of equal linear eccentricity (e ^) e ^ = e ^ and e (4) which are connected by a conductor (13), its angle (β) with the headlamp axis (x) is equal to or less than the angle of engagement (<p _z ) at point (Q) of penetration. 9έΦ _ζ (8) 3 drawings FIG N 0BR.3 253 224 0BR, 5 Severography, n. P., MOST Price 2,40 Kčs He invented the corrections in the printed descriptions The description of the invention to the author's certificate No. 253 224 (6211-85), issued in print on 15.6.1988, is invalid due to serious errors. The correct wording of the description of the invention will be printed again.