BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a structure of a light emitting module of a headlamp for a vehicle according to an exemplary embodiment of the invention,
FIG. 2 is a perspective view showing a state in which only a projection lens and a reflecting plane which serve as cut line forming portions are extracted,
FIG. 3 is a typical view showing a state in which an LED to be a light source is projected by the projection lens,
FIG. 4 is a chart showing a light distribution pattern in the cut line forming portion in the light emitting module of the headlamp for a vehicle according to the embodiment of the invention,
FIG. 5 is a typical view showing a structure of the light distribution pattern,
FIG. 6 is a chart showing a light distribution pattern in a diffusing portion in the light emitting module of the headlamp for a vehicle according to the embodiment of the invention,
FIG. 7 is a horizontal sectional view showing an example of integral molding in the light emitting module of the headlamp for a vehicle according to the embodiment of the invention (a diffusion lens is provided on a front surface of the projection lens, a light source molding type),
FIG. 8 is a horizontal sectional view showing an example of the integral molding in the light emitting module of the headlamp for a vehicle according to the embodiment of the invention (the diffusion lens is not provided on the front surface of the projection lens, the light source molding type),
FIG. 9 is a horizontal sectional view showing an example of the integral molding in the light emitting module of the headlamp for a vehicle according to the embodiment of the invention (the diffusion lens is provided on the front surface of the projection lens, a light source non-molding type),
FIG. 10 is a horizontal sectional view showing an example of the integral molding in the light emitting module of the headlamp for a vehicle according to the embodiment of the invention (the diffusion lens is not provided on the front surface of the projection lens, the light source non-molding type),
FIG. 11 is a view showing an arrangement of a light source and an optical axis in the case in which a shade is disposed on the front surface of the LED,
FIG. 12 is a view showing a light distribution pattern in the case in which the shade is disposed on the front surface of the LED,
FIG. 13 is a typical view showing a light emitting luminous intensity distribution of the LED, and
FIG. 14 is a view showing an optical system for efficiently emitting a light from the LED in a forward direction (the prior art).
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
FIG. 1 is a perspective view showing a structure of a light emitting module of a vehicle headlamp according to an exemplary embodiment of the invention. As shown in the drawing, a light emitting module 100 is constituted by a projection lens 20, a reflecting plane 30 and a diffusion lens 40. An LED 10 in a light emitting portion which is not shown is disposed behind the projection lens 20. The projection lens 20 and the reflecting plane 30 function as cut line forming portions for forming a cut line of a light distribution pattern and the diffusion lens 40 functions as a diffusing portion for diffusing a light emitted from a light source.
FIG. 2 is a perspective view showing only the projection lens 20 and the reflecting plane 30. Differently from the conventional art, the reflecting plane 30 does not have a bowl-shape which is rotationally symmetrical but has a shape of a curved surface having a great curvature in an upper half part. Moreover, an inner surface of the reflecting plane 30 is subjected to a mirror finishing treatment and forms a reflection mirror.
FIG. 3 is a typical view showing a state in which the LED 10 as the light source is projected by the projection lens 20. Description will be given to a positional relationship between the LED 10 and the projection lens 20. The LED 10 is disposed in such a manner that a long side 10a on a lower side of a light emitting plane having an oblong and rectangular shape is positioned in a vicinity of a focal point FP of the projection lens 20. Accordingly, a projected image of the light source generated by the projection lens 20 is positioned on a lower side of an optical axis.
On the other hand, a light which is not incident on the projection lens 20 is reflected by the reflecting plane, that is, the reflection mirror and is thus emitted in a forward direction. In the reflecting plane, a direction of the optical axis, the focal position, and a shape of the reflecting plane are set in such a manner that an image reflected by the reflection mirror is turned downward from an upper side of the image of the projection lens 20. More specifically, as described above, a curvature of an upper curved surface covering an upper side of the projection lens is greater than a curvature of a lower curved surface covering a lower side of the projection lens, and the reflected light does not reach an upper side of the cut line (see FIG. 2). Although the reflecting plane is constituted by a small divided and curved surface in the example of FIG. 2, it is a matter of course that the reflecting plane may be constituted by a smooth and continuous curved surface.
FIG. 4 is a chart showing a light distribution pattern formed by the cut line forming portion (that is the projection lens 20 and reflecting plane 30) in the light emitting module of the vehicle headlamp according to the exemplary embodiment of the invention. Moreover, FIG. 5 is a typical view showing a structure of the light distribution pattern in FIG. 4. As shown in the drawings, the light reflected by the reflection mirror is distributed to a lower region of a cut line. Therefore, it is possible to irradiate a low beam having a high safety without generating a dazzling light toward a car running on an opposing lane.
FIG. 6 is a chart showing a light distribution pattern formed by the diffusing portion in the light emitting module of the vehicle headlamp according to the exemplary embodiment of the invention. As shown in the drawing, a light is properly diffused in a horizontal direction by the diffusion lens 40.
FIGS. 7 to 10 are horizontal sectional views showing an example of integral molding in the light emitting module of the headlamp for a vehicle according to the exemplary embodiment of the invention. In a light emitting module 110 shown in FIG. 7, a diffusion lens is also formed on a front surface of the projection lens, and the LED 10 (not shown) to be the light source is molded. On the other hand, in a light emitting module 120 shown in FIG. 8, the diffusion lens is not formed on the front surface of the projection lens.
A light emitting module 130 shown in FIG. 9 has such a structure that the LED 10 (not shown) to be the light source is not molded, and the diffusion lens is formed on the front surface of the projection lens. On the other hand, similarly, a light emitting module 140 shown in FIG. 10 has such a structure that the LED 10 is not molded, and the diffusion lens is not formed on the front surface of the projection lens.
By molding the projection lens and the reflecting plane integrally with each other as described above, it is possible to easily constitute the light emitting module. In particular, the structure in which the LED 10 is not molded is excellent in an assembling property and a maintenance property.
By disposing a shade 50 on the front surface of the LED 10 and providing a projection lens in such a manner that a side of the shade 50 is coincident with the vicinity of a focal point as shown in FIG. 11, it is also possible to generate a light distribution pattern having a so-called Z-shaped cut line as shown in FIG. 12.
According to the exemplary embodiment, it is possible to obtain a desirable light distribution by forming a light distribution pattern having a cut line through the cut line forming portion constituted by the projection lens 20 and the reflecting plane 30 and carrying out a diffusion in a proper variation through the diffusion lens of the diffusing portion.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
DESCRIPTION OF THE REFERENCE NUMERALS AND SIGNS
10, 11, 12 LED
20, 21 projection lens
30, 31 reflecting plane
40 diffusion lens
50 shade
100, 110, 120, 130, 140 light emitting module
- FP focal point of projection lens
Patent Application
20080074896
