GB2073866A

GB2073866A - A headlamp lens for motor vehicles

Info

Publication number: GB2073866A
Application number: GB8107903A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1980-04-12
Filing date: 1981-03-12
Publication date: 1981-10-21
Also published as: DE3014104A1; FR2480404A1; DE3014104C2; GB2073866B; FR2480404B1

Abstract

The transparent lens of a headlamp which is inclined with respect to the vertical axis of the vehicle has optically effective elements (10) on its inner side. Each element consists of a first prism (11) scattering the incident rays (16) in a horizontal direction and of a second prism (12) which eliminates the bending of the rays in a vertical direction produced by the inclination of the lens. An outwardly refracting element and an element refracting towards the optical axis may form a twin element. <IMAGE>

Description

SPECIFICATION A headlamp for motor vehicles State of the art The transparent lens of headlamps which are incorporated in vehicles is matched to the shape of the body so that, due to the inclination of the front part of the body, each lens is necessarily inclined forwards at the bottom and backwards towards the top; on the other hand, the lens of an additional headlamp fitted below is inclined forwards at the top and backwards towards the bottom corresponding to the shape of the body at that location.

As is known, the optically effective elements of the lens form the incident crude light into a wide light beam, a so-called light strip. The lens inclination influences this light strip disadvantageously because with main headlamps the end sections of the light strip are bent downwards, but with auxiliary headlamps they are bent upwards. The result is a bright-darkboundary of the dipped headlight is much too indefinite and an insufficient illumination of the mad ahead of the vehicle using fog-lights.

Advantages of the invention On the headlamp in accordance with the invention for motor vehicles; the problem described with respect to the state of the art is solved by simple means so that the bright-dark-boundary is sufficiently defined and the road ahead of the vehicle, especially the margin, is illuminated sufficiently. The invention is based on the concept of using optically effective elements with a simply representable configuration in order to obtain a mould favourable to manufacturing techniques and a moulded lens which is free from problems. Moreover, only slight differences in thickness of the individual elements is provided; an advantage to be rated highly in the production of soft glass.

Advantageous further developments of the invention are described in the sub-claims. The distribution of scattered light is adjustable with the form of headlamp according to claim 3 by the size and number of the dispersing elements in the particular region.

Drawing Several embodiments of the invention are illustrated in the drawing and are described in detail in the following specification. Fig. 1 shows an optically effective element in its geometrical construction; Fig. 2 is a sketch showing the principle, through a headlamp projecting the main beam in vertical axial section but not to scale; and Fig. 3 is a partial horizontal section through a lens on an enlarged scale.

Description of the embodiments An optically effective element 10 in Fig. 1 is composed of a first prism 11 and a second prism 1 2 and is formed integrally with a transparent lens 1 3. The upper edge 1 5 of the lens 1 3 is sloped backwards by an angle 1 7 with respect to the vertical axis 14 of the vehicle and is perpendicular to the longitudinal central plane of the vehicle (not shown) which includes the vertical axis and the longitudinal axis. The beam 1 6 represents the incident light rays of the crude light beam leaving the reflector (not shown) and the beam 16' represents the light beam leaving the headlamp influenced optically by the element 10.

The two light refracting surfaces of the second prism 1 2 include the correction angle 22 and converge downwardly. The first prism 11 has a scatter angle 21. The crude light beam 16 is refracted towards the side in a predetermined manner by the scatter angle 21 but is simultaneously deflected downwards by the inclination angle 1 7 in an undesirable manner. This deflection is then eliminated by the correction angle 22 so that the previously described light ray is emitted. The elements formed by the prisms 11, 1 2 are formed on the inner surface of the lens 13.

Fig. 2 shows a reflector 19 provided with a main beam incandescent coil 20 and a lens 23 closing the opening from the reflector 19. The lens is made in one piece from soft glass or plastics material and is formed by the lens 1 3 and a plurality of elements each of which is made up of the first and second prisms 11, 1 2. Two crude light rays 1 6 substantially parallel to the optical axis 1 8 are refracted in the previously described manner by passing through the lens 23, on the one hand, into a horizontal direction (transverse to the sectional plane) and are simultaneously deflected upwards. The second prism 1 2 corrects this deflection in the previously described manner.

The lens 23 in Fig. 3 has a plurality of twin elements (10/10, 10'/10', 10"/10" etc. One of the two elements has a first prism refracting towards the optical axis 1 8 and a second prism refracting towards the outer lens margin 24.

With an inclination angle of 60 degrees and a refractive index of the lens material of 1.5 the following relationships are provided: Horizontal Vertical Correction angle Scatter angle Scatter Scatter (22) (11) (Degrees) (Degrees) 3.27826E 0 0 4.74466 0.034280127 2.5 1.813060204 2.02355 0.137690790 5 3.633341413 1.26362 0.311967060 7.5 5.468231249 1.64960 0.560084134 10 7.32546207 4.56650 0.886393726 12.5 9.213314001 1.11457 1.296821773 15 11.1408586 4.02409 1.799175382 17.5 13.11826853 2.10321 2.403569579 20 15.15722702 9.76426 3.123028994 22.5 17.271489085 1.31583 3.974383593 25 19.47769085 1.40916 4.979600668 27.5 21.79655460 3.46956 6.167802572 30 24.25477128 2.83856 7.578615665 32.5 26.8881259 3.61123

Claims

1. A headlamp for motor vehicles provided with a transparent lens which is inclined with respect to the vertical axis of the vehicle and has optically effective elements for influencing the light rays passing through the lens. characterised by: (a) each element consists of a first prism which scatters the incident light rays in a horizontal direction and (b) of a second prism which corrects the bending of the light rays in a vertical direction produced by the inclination of the lens.

2. A headlamp according to claim 1 the upper edge of the lens of which is inclined backwards with respect to the vertical axis of the vehicle, characterised by: (c) the two light refracting areas of the second prism which corrects the vertical bending of the rays, converging downwards from a main headlamp. converging upwards from a fog-lamp.

3. A headlamp according to claim 1 or 2 characterised by: (d) a plurality of twin elements each of which is made up of an element comprising a laterally outwardly refracting prism and an element comprising a prism refracting towards the optical axis.

4. A headlamp according to one of the preceding claims characterised by: (e) the elements are formed on the inner surface of the lens.

5. A headlamp according to one of the preceding claims characterised by: (f) the lens is a lens which emits main light or auxiliary light.

6. A headlamp according to one of the preceding claims characterised by: (9) the lens consists of plastics material.

7. A headlamp for motor vehicles substantially as herein described with reference to Fig. 1, Fig. 2 or Fig. 3 of the accompanying drawings.

8. A headlamp for motor vehicles, having a correction angle/scatter angle/horizontal scatter/vertical scatter relationship as set forth in the table at the end of the present specification.