JP2009140798A - Vehicle headlight - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle headlight in which a desired light distribution pattern is easily formed, and which is configured to be thin type and lightweighted. <P>SOLUTION: The vehicle headlight includes a light guide plate 21 of which the surface is made a light-emitting face 11b, and which is consisting of a flat plate-shaped and transparent material in a visible light region, and a point-like or a linear light source 12 which is arranged along the longitudinal direction extending laterally against one end face of the light guide plate. The backside of the light guide plate has a prism array 24 which has a saw-tooth shape in a cross-sectional face from the end face along the other end face, and which extends in a direction parallel with the end face, individual prism faces of the prism array 24 are formed so that an incident angle against the light-emitting face becomes smaller when light guided from a light source side is totally reflected, and the projection lens 11 is arranged so that a focal position of its light source device side is positioned on the light-emitting face of the light guide plate 21 of the light source device to constitute the light source device 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light source device using a plurality of point or line light sources, and a vehicle headlamp such as a headlamp and an auxiliary headlamp composed of a convex lens.

  Conventionally, as a vehicular lamp using a light guide plate, for example, a vehicular lamp according to Patent Literature 1 is known, and as a general projector type headlamp, for example, a headlamp according to Patent Literature 2 is known.

The vehicle lamp according to Patent Document 1 is configured as shown in FIG.
That is, in FIG. 15, the vehicle lamp 1 has a housing 2 having an opening 2a for emitting light, a light incident surface 3a, and a light emitting surface 3b, and seals the opening 2a of the housing 2. As described above, the light-transmitting cover member 3 fixedly installed on the housing 2 is provided in a plate shape inside the housing 2, and faces the light incident surface 4a formed on the side surface for taking in light and the cover member. A light guide plate 4 having a front light exit surface 4b and formed with a scattering pattern 4c for scattering light incident on the light entrance surface 4a toward the light exit surface 4b, and light incident on the light guide plate A light source 5 that is provided adjacent to the surface and radiates light to the light incident surface; and a reflection plate 4 d that is provided on the rear surface of the light guide plate 4 and reflects light to the front surface of the light guide plate 4. Yes.
On the light incident surface and / or the light emitting surface of the cover member 3, a lens pattern 3 c for imparting a certain pattern to emitted light is formed.

In this vehicle lamp 1, as shown in FIG. 16, the light emitted from the light source 5 enters the inside from the side surface (light incident surface) 4 a of the light guide plate 4 and totally reflects the inside of the light guide plate 4. The traveling light is scattered by the scattering pattern 4 c formed on the rear surface of the light guide plate 4 and emitted to the front surface (light emitting surface) 4 b of the light guide plate 4.
The light emitted to the front surface of the light guide plate 4 is irradiated forward with an appropriate pattern by the cover member 3 on which the lens pattern is formed.
Here, the light source 5 is configured by arranging a plurality of light emitting diodes (LEDs), and a desired light distribution characteristic can be obtained by arranging a lens or the like on the front surface of the light source 5. .

The headlamp according to Patent Document 2 is configured as a general projector type headlamp, as shown in FIG. That is, the headlamp 6 includes a bulb 7 as a light source, a reflecting surface 8, a projection lens 9, and a light shielding member 9a.
The reflection surface 8 is composed of an elliptical reflection surface having the bulb 7 as a first focal point (rear focal point) and a long axis extending substantially horizontally toward the front in the light irradiation direction, and the inner surface thereof is defined as a reflection surface. Is formed.
The projection lens 9 is composed of a convex lens, preferably an aspheric lens, and the light shielding member 9a is disposed in the vicinity of the focal point on the light source side (rear side).
The light shielding member 9a is for giving a predetermined light distribution pattern for a low beam to the light irradiated forward in the light irradiation direction, and is disposed near the focal point of the projection lens. Moreover, in order to form a cut-off line in the light distribution pattern, the upper edge is formed in a predetermined shape.

According to the headlamp 6 having such a configuration, the light emitted from the bulb 7 is reflected directly or by the reflection surface 8, and on the image plane near the focal point 9b of the convex lens, a desired light distribution pattern. A high illuminance band (high luminance band, light collection band) is created by inverting the image vertically and horizontally, and the high illuminance band is inverted by the projection lens 9 and projected forward in the light irradiation direction.
At that time, a part of the high illuminance zone is blocked by the light shielding member 9a, and a cut-off line C (see FIG. 18) is formed by the upper edge of the light shielding member 9a. Accordingly, the high illuminance zone is projected forward as a passing beam.
The light distribution pattern shown in FIG. 18 is a light distribution pattern of a right-handed headlamp, and the cut-off line C irradiates light slightly above the horizontal line from the center to the right side. Yes.
Special table 2006-509343 JP 2001-076410 A

By the way, in the vehicle lamp 1 according to Patent Document 1, light is extracted from the light guide plate 4 by scattering light by the scattering pattern 4c. Therefore, the irradiated light has a directivity characteristic close to completely scattered light.
Therefore, with the lens pattern 3c as described in Patent Document 1, a light distribution pattern having brightness and a light / dark boundary line necessary as a vehicle headlamp such as a headlamp or an auxiliary headlamp such as a fog lamp is obtained. I couldn't.

  Further, since the light distribution pattern is formed by a plurality of individual lens patterns 3c, the optical setting of each lens pattern 3c becomes complicated. For example, with respect to a certain part of the lens pattern, scattered light from the light guide plate 4 enters from a peripheral part other than the focal position. Accordingly, it is very difficult to form a specific light distribution pattern or cutoff line in front of the lens pattern 3c.

Further, the headlamp according to Patent Document 2 similarly requires a reflecting surface, and in some cases, a light shielding member is required inside the lamp. For this reason, the whole lamp of a headlamp becomes large and heavy, and the depth also becomes large.
Furthermore, the reflecting surface of this headlamp needs to be designed in accordance with the shape of the light emitting part of the bulb as a light source. Therefore, it takes a relatively long time to design such a reflecting surface.

  In view of the above, an object of the present invention is to provide a vehicle headlamp in which a desired light distribution pattern can be easily formed with a simple configuration and can be configured to be thin and lightweight.

According to the present invention, the object is provided with a light source device and a convex projection lens that irradiates light emitted from the light source device forward in the light irradiation direction. A flat plate-like light guide plate made of a transparent material as a light emitting surface, and a point-like or linear light source arranged facing one end face of the light guide plate The back surface of the light guide plate has a prism array extending in a direction parallel to the end surface in a sawtooth shape along the other end surface from the end surface, The prism surface is formed so that the incident angle with respect to the light exit surface becomes small when the light coming from the light source side is totally reflected, and is not totally reflected by the prism surface on the back surface side of the light guide plate. Reflection light that is refracted and transmitted back to the light guide plate A vehicle headlamp, wherein the projection lens is disposed such that a focal position of the light source device is located on a light exit surface of a light guide plate of the light source device, Achieved.

  In the vehicle headlamp according to the present invention, preferably, the projection lens is a cylindrical lens whose axis extends in a lateral direction.

  In the vehicle headlamp according to the present invention, preferably, both ends of the projection lens are formed as convex lenses.

  In the vehicle headlamp according to the present invention, preferably, both ends of the projection lens are formed in a convex shape outward in the lateral direction.

  In the vehicle headlamp according to the present invention, preferably, an angle formed between each prism surface of the prism array and the surface of the light guide plate is in a range of 0 to 45 degrees.

  In the vehicle headlamp according to the present invention, preferably, the light exit surface of the light guide plate has a shape corresponding to the cut-off pattern.

  In the vehicle headlamp according to the present invention, the light source side end face of the light guide plate is preferably located on the cut-off pattern side.

  The vehicle headlamp according to the present invention preferably includes a light guide unit that reflects light from within the light guide plate in regions adjacent to the light source side edges of the front and back surfaces of the light guide plate.

  The vehicle headlamp according to the present invention preferably has a shape corresponding to a cut-off pattern in a region adjacent to the light source side edge of the surface of the light guide plate and transmits light from the surface of the light guide plate. A reflective sheet is provided that reflects inside.

  In the vehicle headlamp according to the present invention, preferably, the light guide plate is formed so as to correct the spherical aberration of the projection lens.

  The vehicle headlamp according to the present invention is preferably formed so that the light guide plate has a curved surface shape corresponding to the spherical aberration of the projection lens.

  In the vehicle headlamp according to the present invention, preferably, an optical sheet for aligning the direction of the maximum luminous intensity of the light emitted from the light guide plate with the optical axis of the projection lens is disposed near the light exit surface of the light guide plate. ing.

  In the vehicle headlamp according to the present invention, the light guide plate is preferably arranged to be inclined with respect to the optical axis of the projection lens in order to maximize the light entering the projection lens.

The present invention projects a high illuminance pattern or a high luminance pattern formed on a light emitting surface of a surface light source device in front of a vehicle by a projection lens.
A high illuminance pattern or a high luminance pattern on the light exit surface is produced as follows.
According to the said structure, the light radiate | emitted from the said light source injects from the end surface of the said light-guide plate, and injects into the output surface or back surface of the said light-guide plate. The light incident on the output surface is refracted and output toward the projection lens or totally reflected depending on the incident angle with the output surface. The totally reflected light is incident on the back surface of the light guide plate. The prism array is formed on the back surface, and light incident on the back surface is totally reflected or refracted depending on an incident angle with the prism surface. When the light is totally reflected by the prism surface, the direction is changed so that the incident angle with the light exit surface becomes small.

  At this time, the degree to which the incident angle is reduced is determined by the angle of the prism surface, and by adjusting the prism angle, the incident angle to the exit surface is set to be smaller than the critical angle by one total reflection on the back surface. Alternatively, it can be set to require multiple reflections. That is, by controlling the prism angle, it is possible to control the density of the light emitted from the exit surface, and a desired high illuminance pattern can be created on the light exit surface.

If the prism angle is set to 45 degrees or less, most of the light can be totally reflected, and the light refracted (transmitted) by the prism surface is reflected by the reflecting sheet and enters from the back surface of the light guide plate. Since the light is returned again into the light guide plate, the loss is small.
As a result, the reflecting mirror 8 is not required, and the overall configuration is small and low-cost.

When the projection lens is a cylindrical lens whose axis extends in the horizontal direction, the projection lens does not have a light condensing property in the horizontal direction, but is disposed in a sufficiently wide range in the horizontal direction with respect to the light source device. Yes. For this reason, the incident efficiency from the light source device is improved, and a brighter light distribution pattern can be formed.
Furthermore, the light transmitted through the projection lens is greatly spread in the left-right direction by the action of the cylindrical lens. Therefore, a wide light distribution pattern can be obtained on the left and right, and in the case of point-like light sources spaced in the horizontal direction, luminance unevenness between the individual light sources can be reduced.

In the case where both ends of the projection lens are formed as convex lenses, near the both ends of the projection lens, light that is incident so as to diffuse obliquely outward from the light guide plate is reflected by the convex portions. Refracts or reflects inward.
Therefore, the luminous intensity near the center in the light distribution pattern is increased.

When the angle formed between the individual prism surfaces of the prism array and the surface of the light guide plate is in the range of 0 to 45 degrees, the opening angle up to about 70 degrees in the vertical direction, that is, the light guide plate and the projection lens are formed. It becomes a corner.
Therefore, the light emitted from the light guide plate is surely incident on the projection lens, the efficiency of incidence on the projection lens is increased, and a brighter light distribution pattern is obtained.

  When the light emitting surface of the light guide plate has a shape corresponding to the cut-off pattern, the light source device can form the cut-off pattern. For this reason, the light shielding member for forming a cut-off pattern becomes unnecessary, and the vehicle headlamp can be configured more easily and at low cost. .

  When the end face of the light guide plate on the light source side is located on the cut-off pattern side, the cut-off line bright / dark border line formed by the cut-off pattern is close to the light source. For this reason, high brightness can be easily obtained, and a good light distribution pattern can be obtained.

  Adjacent to the light source side edge of the light guide plate when a light guide part that reflects light from the inside of the light guide plate is provided in regions adjacent to the light source side edge on the front and back surfaces of the light guide plate In this region, the reflection of light is repeated by the light guide between the front and back surfaces of the light guide plate, thereby reducing luminance unevenness due to the interval between the plurality of point-like light sources arranged side by side. For this reason, a light distribution pattern with a more uniform luminance can be formed.

  In a case where a region corresponding to the cut-off pattern is provided in a region adjacent to the light source side edge of the surface of the light guide plate and a reflection sheet that reflects light from the surface of the light guide plate into the light guide plate is provided. In the light distribution pattern, a cut-off pattern is formed based on the shape of the reflection sheet. Further, the light blocked by the cutoff is reflected by the reflection sheet and returned to the light guide plate, so that the utilization efficiency of the light from the light source is improved.

When the light guide plate is formed so as to correct the spherical aberration of the projection lens, and preferably has a curved shape corresponding to the spherical aberration of the projection lens, the spherical aberration of the projection lens is The correction is made by the curved shape of the light guide plate, and the influence of spherical aberration can be reduced.
Even if there is some spherical aberration of the projection lens, the influence of the spherical aberration is small, so that an inexpensive projection lens having a relatively large spherical aberration can be used.

When the optical sheet for aligning the direction of the maximum luminous intensity of the light emitted from the light guide plate with the optical axis of the projection lens is disposed near the light exit surface of the light guide plate, or of the light emitted from the light guide plate When the light guide plate is inclined with respect to the optical axis of the projection lens in order to align the direction of the maximum luminous intensity with the optical axis of the projection lens, the emitted light from the light source device With respect to the optical axis of the projection lens, the direction in which the light reflected by the prism array on the back surface of the light guide plate is the highest can be aligned. As a result, the light entering the projection lens is increased, and the luminous intensity of the irradiation pattern can be increased.
In addition, when the light guide plate is inclined, the size in the inclination direction can be reduced even with a relatively large light guide plate. For this reason, it is possible to relatively increase the resolution of the luminance control element.

  Thus, according to the present invention, it is possible to provide a vehicle headlamp that can easily be formed with a simple configuration and that can be configured to be thin and lightweight.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
The embodiments described below are reference examples and preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these embodiments.

[Example 1]
FIG. 1 shows the configuration of a first embodiment of a vehicle headlamp according to the present invention.
In FIG. 1, a vehicle headlamp 10 includes a light source device 20 and a projection lens 11 that focuses light from the light source device 20.
The light source device 20 is configured as described later, and emits light forward in the light irradiation direction near the center of the rear end surface of the box-shaped housing 12 opened toward the front of the vehicle headlamp 10. It arrange | positions so that it may radiate | emit.
The projection lens 11 is composed of a convex lens, and is disposed on the light emitting surface of the light source device 20 so that the focal position F on the light source device 20 side is located.

  Here, as shown in FIG. 2, the light source device 20 includes a light guide plate 21 and a plurality of LEDs 22 as light sources.

In the case shown in the drawing, the light guide plate 21 is made of a flat plate-like light-transmitting material, that is, a material transparent in the visible light region.
Here, the light guide plate 21 is made of a transparent resin or glass generally used for optical applications such as polycarbonate and acrylic resin.

The light guide plate 21 is configured such that one end thereof, the end surface on the near side in FIG. 1 is an incident surface 21a, and the upper surface is a light emitting surface 21b, and the back surface (bottom surface) and both left and right side surfaces are shielded from light. It is covered with the housing | casing 23 which consists of a property material.
In the illustrated case, the light guide plate 21 is formed in a wedge shape in cross section so that the thickness gradually decreases from the incident surface 21a to the opposite end surface. It may be formed.

Here, in the light guide plate 21, the incident surface 21a may be provided with a fine shape made of, for example, a prism or a circular arc or roughened in order to improve the incident efficiency.
On the other hand, the light guide plate 21 may have a light emitting surface 21b having a prism, lenticular shape, or the like in order to improve luminance or adjust light distribution.

Further, as shown in FIG. 2, the light guide plate 21 has a light output surface 21b in a shape corresponding to a light distribution pattern to be irradiated, that is, a shape obtained by reducing and reversing the light distribution pattern, for example, in a vehicle. It is formed so as to be in the shape of a cut-off pattern of the passing beam of the headlamp.
Therefore, the light guide plate 21 has an end surface 21a on the front side forming a step portion near the center as shown in FIG.

Further, as shown in FIG. 3, the light guide plate 21 has a prism array 24 on its back surface (bottom surface).
In the illustrated case, the prism array 24 is formed so as to extend in a sawtooth shape in cross section from the incident surface 21a toward the opposite end surface and in a bowl shape in the lateral direction.
Among the light incident from the incident surface 21a of the light guide plate 21, when the light incident on the individual prism surfaces 24a of the prism array 24 is totally reflected, the light is inclined so that the incident angle with respect to the output surface becomes small. Is formed.
As a result, as shown in FIG. 3, most of the light L incident into the light guide plate 21 is totally reflected by the inner surfaces 24 a of the individual prisms of the prism array 24 and totally reflected by the upper surface of the light guide plate 21. Thus, the reflection is repeated.
Such reflected light is gradually emitted upward as the outgoing light L1 from the light outgoing surface 21b of the light guide plate 21 when the incident angle with respect to the light guide plate 21 gradually decreases and the incident angle becomes smaller than the critical angle. It is like that.
In the light L in the light guide plate 21, the incident angle with the prism surface 24 a is smaller than the critical angle, and the light L 2 that passes through the back surface may be obtained. However, the light L2 that has passed through the back surface is reflected by the reflection sheet 26 and returned to the light guide plate. Therefore, the loss is only the absorption of the reflection sheet, and the loss is small if a high reflectance material such as a silver reflection sheet or a foamed resin sheet is used.

Such a light guide plate 21 can be formed from the above-described transparent resin material by injection molding, press molding or extrusion molding using a mold having a desired shape, or a desired mold from glass. It can be manufactured by press molding.
The light guide plate 21 can be manufactured by processing the prism array 24 on a plate-like material made of a transparent resin formed by injection molding or extrusion molding.

Here, the light guide plate 21 has an optical sheet 25 (two optical sheets in the case of illustration) on the surface as necessary in order to improve the luminance of light emitted from the surface or to adjust the light distribution characteristics. 25a, 25b).
Thereby, the direction and directivity of the light emitted from the light exit surface 21 b of the light guide plate 21 are appropriately changed by the optical action of the optical sheet 25, and the emitted light from the light guide plate 21 is directed to the projection lens 11. Can be guided reliably.

As such optical sheets 25a and 25b, prism sheets and diffusion films used in general surface light source devices can be used.
Prism sheet is generally used in optical applications by imparting a prism shape by press molding or extrusion molding with a mold to a film made of thermoplastic transparent resin that is generally used in optical applications. The film made of an ultraviolet curable transparent resin can be manufactured by imparting a prism shape by a molding method such as 2P method.

  In addition, the diffusion film is formed by forming a resin or glass bead having a different refractive index on both sides or one side of a film obtained by extrusion molding composed of a thermoplastic transparent resin generally used in optical applications. Alternatively, it can be produced by mixing a resin having a different refractive index or a glass bead into a thermoplastic transparent resin generally used in optical applications, and forming it into a film by extrusion or the like.

In addition, the light guide plate 21 returns light leaking from the back and side surfaces thereof into the light guide plate 21 to improve the light use efficiency from each LED 22 as a light source. A reflective film 26 may be disposed to face the end surface 21c, the back surface 21d, and the left and right side surfaces 21e and 21f, respectively.
Here, the reflective film 26 is preferably a silver film or a high reflectance white sheet.
High reflectivity white sheet is oxidized to high reflectivity metal reflective film, polycarbonate resin, etc. in which metal such as aluminum or silver is formed by vapor deposition or sputtering method on resin member formed by extrusion molding etc. Resin film or resin plate to which a visible light diffusive reflector such as titanium is added, or a resin film or resin formed by distributing micropores by supercritical fluid, fine foam molding or foam molding by chemical foaming agent, etc. It can be manufactured from a board.

When the inner surface of the housing 23 is configured as a reflective surface, at least a part of the inner surface of the housing 23 can be used instead of the reflective film 26.
In order to configure the inner surface of the housing 23 as a reflective surface, a high-reflectance metal thin film may be formed directly on the inner surface of the housing 23 made of resin or metal, for example, by vapor deposition or sputtering. .

Each LED 22 is arranged in a line so as to face the incident surface 21 a of the light guide plate 21.
Here, the LEDs 22 do not need to be arranged at equal intervals, and along the incident surface 21a of the light guide plate 21 so that a predetermined luminance distribution is obtained on the light emitting surface 21b of the light guide plate 21. They are arranged at appropriate intervals.
In addition, although each LED22 is arrange | positioned at 1 row in the figure, it is not restricted to this, You may arrange | position at multiple rows.

The vehicle headlamp 10 according to the embodiment of the present invention is configured as described above, and each LED 22 of the light source device 20 is driven and emits light when a driving voltage is applied from an external driving circuit (not shown).
Light emitted from each LED 22 enters the inside from the incident surface 21a of the light guide plate 21 and is repeatedly returned to the light guide plate by the total reflection and reflection sheet 26 on the front surface, back surface, and both side surfaces of the light guide plate 21. However, the light L3 emitted from the emission surface 21b toward the projection lens 11 travels to the opposite end surface and exits from the end surface 21c.
The light emitted from the end face 21 c is reflected by the reflection sheet 26 c and returned to the light guide plate 21. The returned light L4 is bent between the prism surface 24a and the tapered surface 24b of the prism array 24 so that the incident angle on the tapered surface 24b becomes larger, and the incident angle on the tapered surface 24b becomes larger than the critical angle. At this stage, the light is totally reflected and emitted from the emission surface 21b, and the emission surface 21b emits light with higher luminance.

The light emission shape of the light emission surface 21b of the light guide plate 21 is projected forward by the projection lens 11 in the light irradiation direction.
Thereby, the light emission shape of the light emitting surface 21b is enlarged and inverted and projected in front of the light irradiation direction.
In this case, the edge on the incident surface 21a side of the light emitting surface (front surface) of the light guide plate 21 has a shape corresponding to the cut-off pattern as shown in FIG. Thereby, the light emission shape corresponding to the light distribution pattern suitable for the passing beam in the vehicle headlamp is formed.
Therefore, this light emission shape is projected forward by the projection lens 11 in the light irradiation direction. As a result, a light distribution pattern suitable for a passing beam of an automobile can be formed.

In this case, the light emission surface 21b of the light guide plate 21 in the light source device 20 has a light emission shape corresponding to the light distribution pattern. This eliminates the need for a light-shielding member that forms a reflection surface and a cut-off line for generating a light distribution pattern, such as a conventional projector-type vehicle headlamp.
Therefore, the depth of the entire vehicle headlamp 10 is greatly reduced in the front-rear direction, and the vehicle headlamp 10 can be configured to be small and lightweight. Further, since no light shielding member is required, the number of parts can be reduced, and the parts cost and assembly cost can be greatly reduced.

Moreover, the incident surface 21a side of the light emitting surface 21b of the light guide plate 21 has a cut-off pattern shape. For this reason, high brightness can be easily obtained on the incident surface 21a of the light emitting surface 21b.
Therefore, the cut-off line bright / dark boundary line of the light distribution pattern formed by the incident surface 21a side can be projected clearly with high luminance.
Further, the LEDs 22 are arranged at shorter intervals in an area where high luminance is required in the light distribution pattern. Thereby, high brightness can be easily obtained.

[Example 2]
FIG. 4 shows a second embodiment of a vehicle headlamp according to the present invention.
In FIG. 4, the vehicle headlamp 30 has substantially the same configuration as the vehicle headlamp 10 shown in FIG. 1, and therefore the same components are denoted by the same reference numerals and description thereof is omitted.
The vehicle headlamp 30 has a different configuration only in that the light source device 20 is disposed to be inclined with respect to the optical axis of the projection lens 11.

In this embodiment, the optical device 20 has an upper edge in the illustrated case so that the direction in which the light reflected by the prism array 24 of the light guide plate 21 is emitted from the light emission surface 21 b is aligned with the optical axis of the projection lens 11. Is arranged so as to tilt forward.
At that time, the light source device 20 is arranged so that the position where the cut-off line on the incident surface 21 a side of the light guide plate 21 is formed is located near the focal position on the light source device 20 side of the projection lens 11.

Here, in general, the light emitted from the light source device 20 and not incident on the projection lens 11 does not contribute to the formation of the light distribution pattern. For this reason, the light extraction efficiency from the light source apparatus 20 will fall.
Accordingly, it is desirable that the directivity characteristics of the light emitted from the light source device 20, that is, the light guide plate 21, be within the angle (opening angle) formed by the light guide plate 21 and the projection lens 11. In consideration of the actual diameter of the projection lens 11, the opening angle is generally around 70 degrees.

By the way, in the light guide plate 21 having the above-described configuration, the prism angle of the prism array 21 (the inclination angle of the prism inner surface facing the incident surface 21a) and the directivity characteristic of the emitted light are related to each other. When the directional characteristics in the vertical direction of the light guide plate 21 when the prism angle was changed to 2 to 45 degrees were calculated and simulated, the results shown in the graph of FIG. 5 were obtained.
That is, according to FIG. 5, it can be seen that when the prism angle is small, the directivity is narrow, and when the prism angle is large, the directivity is wide and the direction of the maximum luminous intensity is changed.

  Accordingly, in the vehicle headlamp 10 shown in FIG. 1, the optical sheet 25 is used to guide the light from the optical device 20 to the projection lens 11 (or in the lateral direction on the light emitting surface 21 b of the light guide plate 21). An appropriate prism angle extending, for example, a prism of about 60 to 110 degrees is processed). Thereby, the directivity is adjusted so as to face the projection lens. However, in the vehicle headlamp 30 shown in FIG. 4, the light source device 20 itself projects so that the emitted light faces the projection lens. The lens 21 is disposed to be inclined with respect to the optical axis.

  The above structure is suitable when the directivity of the light guide plate 21 is narrow, and the apparent vertical width of the light guide plate 21 as shown in FIG. As W1 is reduced and the light guide plate 21 approaches the projection lens, the light emitted from the light guide plate 21b is reliably incident on the projection lens 21 and the light utilization rate is improved. When the apparent vertical width W1 is reduced, a light distribution pattern narrow in the vertical direction suitable for a headlamp or a fog lamp can be easily formed. On the other hand, when the directivity is wide, the apparent vertical width W2 becomes large as shown in FIG. 6B. In that case, the structure of the first embodiment may be adopted.

According to the vehicle headlamp 30 having such a configuration, since it operates in the same manner as the vehicle headlamp 10 and it is not necessary to use the relatively expensive optical sheet 25, the cost can be reduced as a whole.
Further, since the light source device 20 is disposed at an inclination, the light guide plate 21 is disposed closer to the projection lens 11. For this reason, the incident efficiency to the projection lens 11 can be further improved.
Furthermore, the occupation height in the housing | casing 23 becomes small because the light source device 20 is inclined and arrange | positioned. For this reason, conversely, if the occupied height is the same, a larger light guide plate 21 can be used. Therefore, the apparent vertical width of the light guide plate 21 is reduced, and a light distribution pattern with a narrow vertical width is easily obtained.

[Example 3]
FIG. 7 shows a configuration of a third embodiment of the vehicle headlamp according to the present invention.
In FIG. 7, the vehicle headlamp 40 has substantially the same configuration as that of the vehicle headlamp 30 shown in FIG. 4, and thus the same components are denoted by the same reference numerals and description thereof is omitted.
The vehicle headlamp 40 is different from the projection lens 11 only in that a projection lens 41 that is long in the horizontal direction is arranged corresponding to the light source device 20 that is long in the horizontal direction.

  The projection lens 41 has a shape in which the projection lens 11 described above is divided into left and right from the center, separated from each other according to the length of the light guide plate 21 in the lateral direction, and connected therebetween by a cylindrical lens 41a.

The vehicle headlamp 40 having such a configuration functions in the same manner as the vehicle headlamp 30 shown in FIG.
Further, the projection lens 41 includes a cylindrical lens 41a, and its incident surface is wide in the lateral direction. For this reason, the incident efficiency to the projection lens from the said light-guide plate 21 is improved.
FIG. 8 shows the result of a calculation simulation of the directivity characteristics in the left-right direction of the light guide plate 21 when the prism angle is changed from 2 to 45 degrees in the light guide plate 21. As shown in the graph of FIG. 8, the prism array 24 is parallel to the light incident surface 21a and does not have light condensing properties in the left-right direction. That is, since light that spreads in the left-right direction comes out from the light guide plate 21, the cylindrical lens 21a that is wide in the left-right direction is particularly effective in increasing the incident efficiency from the light guide plate 21 to the projection lens. .

  Further, as shown in FIG. 7A, the light incident on the cylindrical lens 41a spreads in the left-right direction, and it is easy to form a wide light distribution pattern in the left-right direction. In addition, luminance unevenness based on the distance between LEDs in the light distribution pattern can also be reduced.

  Further, the light incident on the convex lens portions at the left and right ends of the projection lens 41 is refracted inward in the left-right direction and irradiated forward in the light irradiation direction, and the luminous intensity near the center in the light distribution pattern is increased.

[Example 4]
FIG. 9 shows the configuration of the fourth embodiment of the vehicle headlamp according to the present invention.
In FIG. 9, since the vehicle headlamp 50 has substantially the same configuration as the vehicle headlamp 40 shown in FIG. 7, the same components are denoted by the same reference numerals and description thereof is omitted.
The vehicle headlamp 50 is different from the vehicle headlamp 40 shown in FIG. 7 only in that the light source device 20 is arranged vertically.

  According to the vehicle headlamp 50 having such a configuration, the light that has been operated in the same manner as the vehicle headlamp 40 illustrated in FIG. 7 and the light emitted from the light emitting surface 21b of the light guide plate 21 in the light source device 20 is optical. The directivity is adjusted by the sheet 25 and the light enters the projection lens 41.

[Example 5]
FIG. 10 shows the configuration of a fifth embodiment of a vehicle headlamp according to the present invention.
In FIG. 10, since the vehicle headlamp 60 has substantially the same configuration as the vehicle headlamp 40 shown in FIG. 7, the same reference numerals are given to the same components and the description thereof is omitted. The vehicle headlamp 60 includes a projection lens 61 instead of the projection lens 41 as compared with the vehicle headlamp 40 shown in FIG.
The projection lens 61 is composed only of a cylindrical lens having an axis extending in the left-right direction.

According to the vehicle headlamp 60 having such a configuration, the vehicle headlamp 40 operates in the same manner as the vehicle headlamp 40 shown in FIG.
In this case, no convex lens is provided near the left and right ends of the projection lens 61. For this reason, the light emitted from the light guide plate 21 in the left-right direction is not condensed near the center of the light distribution pattern by the convex lens, but is reflected inward in the horizontal direction by internal reflection and contributes to the formation of the light distribution pattern.
Therefore, a desired light distribution pattern can be formed in a fog lamp or the like where the maximum luminous intensity is not so important.

[Example 6]
FIG. 11 shows the configuration of a sixth embodiment of the vehicle headlamp according to the present invention.
11, the vehicle headlamp 70 has substantially the same configuration as the vehicle headlamp 60 shown in FIG. 10, and therefore, the same components are denoted by the same reference numerals and description thereof is omitted.
The vehicle headlamp 70 is different from the vehicle headlamp 60 shown in FIG. 10 only in that the light source device 20 is arranged vertically.

  According to the vehicle headlamp 70 having such a configuration, the light that operates in the same manner as the vehicle headlamp 60 illustrated in FIG. 10 and the light emitted from the light emitting surface 21b of the light guide plate 21 in the light source device 20 is converted into the optical sheet. The directivity characteristic is adjusted by 25 and enters the projection lens 61.

[Example 7]
FIG. 12 shows the configuration of the seventh embodiment of the vehicle headlamp according to the present invention.
In FIG. 12, the vehicle headlamp is configured similarly to the vehicle headlamps shown in FIGS. 1, 4, 7, 9, 10, and 11. The configuration differs only in that the device 80 is provided.

Compared to the light source device 20 shown in FIG. 2, the light source device 80 has a light emission surface 21 b that is not formed in a cut-off pattern shape, and has a predetermined edge region on the incident surface 21 a side. A light guide part 81 having a width is provided.
The light guide unit 81 is configured by a reflection sheet 81 a placed on the surface of the light guide plate 21 in the region.
Furthermore, the edge 81b on the opposite side to the incident surface 21a of this reflection sheet 81a is formed in the shape corresponding to a cut-off line.

  According to the vehicle headlamp having such a configuration, in the light source device 80, the light incident on the light guide plate 21 from the incident surface 21 a is transmitted to the back surface of the light guide plate 21 or the reflective film 26 at the light guide unit 81. The reflection is repeated with the reflection sheet 81a. Thereby, the incident light is sufficiently diffused in the light guide plate 21 particularly in the left-right direction. For this reason, luminance unevenness based on the distance between the LEDs 22 is reduced, and a cut-off pattern is formed by the contour of the edge 81b of the reflection sheet 81a.

[Example 8]
FIG. 13 shows the configuration of an eighth embodiment of a vehicle headlamp according to the present invention.
In FIG. 13, the vehicle headlamp 90 has substantially the same configuration as the vehicle headlamp 10 shown in FIG. 1, and thus the same components are denoted by the same reference numerals and description thereof is omitted. In the vehicle headlamp 90, the entire light guide plate 21 in the light source device 20 corrects this spherical aberration in the left-right direction corresponding to the spherical aberration direction of the projection lens 11 for projecting the light exit surface 21b. Thus, it is formed to be curved.

According to the vehicle headlamp 90 having such a configuration, the light guide plate 21 acts in the same manner as the vehicle headlamp 10 shown in FIG. 1, and the light guide plate 21 is formed to be curved corresponding to the spherical aberration of the projection lens 11. ing. For this reason, the spherical aberration of the projection lens 11 is corrected by the curvature of the light guide plate 21.
Therefore, the light distribution pattern irradiated by the projection lens 11 toward the front of the light irradiation direction on the light guide plate 21 is formed without being affected by the spherical aberration of the projection lens 11 so much.
Conversely, in anticipation of correction of the spherical aberration of the projection lens by the curvature of the light guide plate 21, the projection lens 11 can be allowed to have a certain degree of spherical aberration. It becomes possible to use. Thereby, the component cost of the whole vehicle headlamp can be reduced.

[Example 9]
FIG. 14 shows the configuration of a ninth embodiment of a vehicle headlamp according to the present invention.
In FIG. 14, the vehicle headlamp 100 has substantially the same configuration as the vehicle headlamp 50 shown in FIG. 9, and thus the same components are denoted by the same reference numerals and description thereof is omitted.
Compared with the vehicle headlamp 50 shown in FIG. 9, the vehicle headlamp 100 has a spherical aberration of the projection lens 11 for projecting the light exit surface 21b with respect to the horizontal direction of the entire light guide plate 21. The lens is curved so as to correct the spherical aberration in accordance with the direction.

  According to the vehicle headlamp 100 having such a configuration, it operates in the same manner as the vehicle headlamp 50 shown in FIG. 9, for example, cuts into a light distribution pattern irradiated forward by the projection lens in the light irradiation direction. An off pattern is formed.

  In the embodiment described above, the light distribution characteristic for the passing beam with respect to the vehicle headlamp is limited to the case of left-hand traffic, so as not to give illusion light to the oncoming vehicle on the right side toward the front of the vehicle. The cut-off pattern does not irradiate light above the horizontal line, but this is not limited to this, and in the case of right-hand traffic, the arrangement of the cut-off pattern is reversed left and right in the vehicle headlamp. The effect of will be obtained.

  In the embodiment described above, the LED 22 that is a plurality of point light sources is used as the light source. However, the present invention is not limited to this, and other point light sources such as a semiconductor laser element may be used. It is obvious that a linear light source may be used as long as the luminance control element 24 in the light guide plate 21 can define a desired luminance distribution on the light exit surface 21b.

  The vehicle headlamp according to the present invention is applicable not only to a headlamp but also to any vehicle headlamp including an auxiliary headlamp such as a fog lamp and a driving lamp.

  Thus, according to the present invention, a vehicle headlamp can be provided in which a desired light distribution pattern is easily formed with a simple configuration, and can be configured to be thin and lightweight.

It is a schematic longitudinal cross-sectional view which shows the structure of 1st embodiment of the vehicle headlamp by this invention. It is a disassembled perspective view which expands and shows the light source device in the vehicle headlamp of FIG. FIG. 3 is a partially enlarged longitudinal sectional view showing a sectional shape of a light guide plate in the light source device of FIG. 2. It is a schematic longitudinal cross-sectional view which shows the structure of 2nd embodiment of the vehicle headlamp by this invention. 3 is a graph showing vertical directivity with respect to a prism angle of a light guide plate in the light source device of FIG. 2. It is a schematic sectional drawing which shows the inclination arrangement | positioning of the light source device in case the (A) directivity characteristic of the light-guide plate in the vehicle headlamp of FIG. 4 is narrow, and (B) wide directivity characteristics. It is (A) schematic cross-sectional view and (B) schematic longitudinal cross-sectional view which show the structure of 3rd embodiment of the vehicle headlamp by this invention. 3 is a graph showing the directivity characteristics in the left-right direction with respect to the prism angle of the light guide plate in the light source device of FIG. 2. It is (A) schematic cross-sectional view and (B) schematic longitudinal cross-sectional view which show the structure of 4th embodiment of the vehicle headlamp by this invention. It is (A) schematic cross-sectional view and (B) schematic longitudinal cross-sectional view which show the structure of 5th embodiment of the vehicle headlamp by this invention. It is (A) schematic cross-sectional view and (B) schematic longitudinal cross-sectional view which show the structure of 6th embodiment of the vehicle headlamp by this invention. It is a schematic perspective view which shows the structure of the optical apparatus in 7th embodiment of the vehicle headlamp by this invention. It is (A) schematic cross-sectional view and (B) schematic longitudinal cross-sectional view which show the structure of 8th embodiment of the vehicle headlamp by this invention. It is (A) schematic cross-sectional view and (B) schematic longitudinal cross-sectional view which show the structure of 9th embodiment of the vehicle headlamp by this invention. It is a disassembled perspective view of the light source which shows a structure of an example of the conventional vehicle lamp. It is a fragmentary sectional view which shows the structure of the principal part in the lamp | ramp for vehicles of FIG. It is a schematic sectional drawing which shows the structure of an example of the conventional headlamp. It is a graph which shows the light distribution pattern by the headlamp of FIG.

Explanation of symbols

10, 30, 40, 50, 60, 70, 80, 90, 100 Vehicle headlight 11 Projection lens 12 Housing 20 Light source device 21 Light guide plate 21a Incident surface 21b Light exit surface 21c End surface 21d Back surface 21e, 21f Side surface 22 LED (light source)
DESCRIPTION OF SYMBOLS 23 Case 24 Prism array 25, 25a, 25b Optical sheet 26 Reflective film 41 Projection lens 41a Cylindrical lens 61 Projection lens 80 Light source device 81 Light guide part 81a Reflection sheet 81b Edge

Claims (12)

A light source device, and a convex projection lens that irradiates light emitted from the light source device forward in the light irradiation direction, and
The light source device is arranged along a longitudinal direction extending laterally opposite to one end surface of the light guide plate and a flat plate-like visible light region transparent material having a light emitting surface as a surface. A pointed or linear light source,
The back surface of the light guide plate has a prism array extending in a direction parallel to the end surface in a sawtooth shape from the end surface along the other end surface;
Each prism surface of the prism array is formed so that the incident angle with respect to the light exit surface becomes small when the light guided from the light source side is totally reflected,
The projection lens is disposed such that the focal position on the light source device side is located on the light exit surface of the light guide plate of the light source device.
A vehicle headlamp characterized by that.   The vehicle headlamp according to claim 1, wherein the projection lens is a cylindrical lens whose axis extends in a lateral direction.   The vehicle headlamp according to claim 2, wherein both ends of the projection lens are formed as convex lenses.   The vehicle headlamp according to any one of claims 1 to 3, wherein an angle formed by each prism surface of the prism array and the surface of the light guide plate is in a range of 0 to 45 degrees.   The vehicle headlamp according to any one of claims 1 to 4, wherein the light emitting surface of the light guide plate has a shape corresponding to a cut-off pattern.   6. The vehicle headlamp according to claim 5, wherein an end surface of the light guide plate on a light source side is located on a cut-off pattern side.   The light guide part which eliminates the brightness | luminance nonuniformity of the light from a light source is provided in the area | region adjacent to the light source side edge of the back surface of the said light guide plate, The said any one of Claim 1 to 4 characterized by the above-mentioned. Vehicle headlamps.   A region adjacent to the light source side edge of the surface of the light guide plate is provided with a reflective sheet having a shape corresponding to the cut-off pattern and reflecting light from the surface of the light guide plate into the light guide plate. 8. A vehicle headlamp according to claim 7, characterized in that   The vehicle headlamp according to any one of claims 1 to 8, wherein the light guide plate is formed so as to correct spherical aberration of the projection lens.   The vehicle headlamp according to claim 9, wherein the light guide plate is formed to have a curved shape corresponding to the spherical aberration of the projection lens.   The optical sheet for adjusting the direction of the maximum luminous intensity of the light emitted from the light guide plate to the optical axis of the projection lens is disposed in the vicinity of the light exit surface of the light guide plate. The vehicle headlamp according to any one of 10.   11. The light guide plate according to claim 1, wherein the light guide plate is disposed to be inclined with respect to an optical axis of the projection lens in order to maximize light entering the projection lens. Vehicle headlamps.

Images