Lamp unit for vehicle

In a lamp unit for a vehicle, light incident into a translucent member from a light emitting element is reflected by the inner surface of the translucent member reflecting surface and irradiated from the irradiating surface of the translucent member in the forward direction of the lamp unit. The reflecting surface is vertically shaped as a concave curved formed by a hyperbola. The focusing point is the light emitting center of the light emitting element, whereby the reflecting light is irradiated as spread light from the virtual image position of the light emitting element formed by the reflecting surface within the vertical section. The irradiating surface is vertically shaped as a convex curve formed by an ellipse which focusing point is the virtual image position. The irradiating light can be made substantially parallel rays within the vertical section.

This application claims foreign priority based on Japanese patent application JP 2003-426714, filed on Dec. 24, 2003, the contents of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lamp unit for a vehicle using a light emitting element such as a light emitting diode as a light source.

2. Description of the Related Art

A related art lamp unit for a vehicle using a light emitting diode as a light source has been employed. For example, JP-A-2002-50214 describes a lamp unit for a vehicle having a light emitting diode directed in the forward direction of the lamp unit and a light transmission (translucent) member that covers the light emitting diode from the front side thereof.

This related art lamp unit is such that light from the light emitting diode incident at the rear end portion of the translucent member thereof is introduced to the front end surface of the translucent member. Then, the light is emitted from the front end portion to irradiate the forward area of the lamp unit through a projection lens. When the translucent member described in the above-mentioned JP-A-2002-50214 is used, the utilization factor of light from the light emitting diode can be improved.

However, since the translucent member is configured in a substantially horn shape, there arise related art problems. For example, but not by way of limitation, the irradiation light from the translucent member cannot be controlled accurately, and the length of the lamp unit in the front-to-rear direction thereof (i.e., the longitudinal direction of a vehicle) becomes longer.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a lamp unit for a vehicle using a light emitting element as a light source, which enhances not only the utilization factor of light from the light emitting element, but also controls irradiation light accurately. Further, the present invention can reduce the length of the lamp unit in the longitudinal direction of a vehicle.

While the foregoing objects are provided for the present invention, it is not necessary for these objects to be achieved in order for the invention to operate properly. Further, other object, or no objects at all, may be achieved by the present invention without affecting its operation.

The invention attains the aforesaid object such that a translucent member is disposed to cover a light emitting element from the front side thereof and an improvement is made to the surface configuration of the translucent member.

More specifically, a lamp unit for a vehicle according to the invention is arranged in such a manner that in the lamp unit for a vehicle comprising a light emitting element disposed in a direction and a translucent member disposed to cover the light emitting element from a forward side of the light emitting element, the lamp unit for a vehicle is characterized in that

a part of a surface of the translucent member is configured as a reflecting surface which reflects light, incident into the translucent member from the light emitting element, by an inner surface of the reflecting surface, and another part of the surface of the translucent member is configured as an irradiating surface which irradiates the light, irradiated from the light emitting surface and reflected by the inner surface of the reflecting surface, in a forward direction of the lamp unit, and

the reflecting surface is set, in its vertical sectional shape along a plane passing through a light emitting center of the light emitting element, to have a concavely curved shape formed by a hyperbola which focusing point is near the light emitting center, and the irradiating surface is set, in its vertical sectional shape along the plane, to have a convexly curved shape formed by an ellipse which focusing point is near a virtual image position of the light emitting element formed by the reflecting surface.

The “light emitting element” means a light source with an element configuration having a light emitting portion for emitting light of a substantially point shape, and the kind of the light emitting element is not limited to a particular one, and so a light emitting diode, a laser diode etc. may be employed as the light emitting element, for example.

The “direction” is not limited to a particular direction so long as the light, incident into the translucent member from the light emitting element, can be reflected by the inner surface of the reflecting surface and then can be irradiated from the irradiating surface in the forward direction of the lamp unit.

The “translucent member” is not limited in its material to particular one so long as it is a member with translucency, and so a member formed by transparent composite resin, a member formed by glass etc. maybe employed as the translucent member, for example.

The “plane” is not limited in its direction to a particular direction so long as it is a plane passing through the light emitting center of the light emitting element.

Although the “reflecting surface” is set, in its vertical sectional shape along the plane, to have the concavely curved shape formed by the hyperbola, the sectional shape of the reflecting surface along a plane orthogonal to the plane is not limited to a particular shape.

Although the “irradiating surface” is set, in its vertical sectional shape along the plane, to have the convexly curved shape formed by the ellipse, the sectional shape of the irradiating surface along the plane orthogonal to the plane is not limited to a particular shape.

As shown in the aforesaid configuration, in the lamp unit for a vehicle according to the invention, since the translucent member is disposed to cover the light emitting element from the forward side of the light emitting element, the utilization factor of light from the light emitting element can be enhanced.

In this case, since the reflecting surface constituting a part of the surface of the translucent member is set, in its vertical sectional shape along the plane passing through the light emitting center of the light emitting element, to have the concavely curved shape formed by the hyperbola which focusing point is near the light emitting center, the reflecting surface reflects on the inner surface thereof the light incident into the translucent member from the light emitting element in a manner that the light is reflected as if it is emitted from the virtual image position of the light emitting element formed by the reflecting surface, within the plane.

Further, since the irradiating surface constituting another part of the surface of the translucent member is set, in its vertical sectional shape along the plane, to have the convexly curved shape formed by the ellipse which focusing point is near the virtual image position of the light emitting element, the irradiating surface acts to irradiate the light, irradiated from the light emitting element and then reflected by the inner surface of the irradiating surface, in the forward direction of the lamp unit from the translucent member as parallel rays within the plane. In this case, when the eccentricity of the ellipses constituting the convexly curved shape is set to a reciprocal of the refractive index n of the translucent member, the light irradiated from the translucent member can be set to substantially accurate parallel rays.

Thus, even when the length of the translucent member in the longitudinal direction of a vehicle is set to be short, the irradiating light from the translucent member can be controlled accurately.

In this manner, according to the invention, in the lamp unit for a vehicle using a light emitting element as a light source, the utilization factor of light from the light emitting element can be enhanced, and not only the irradiation light from the lamp unit can be controlled accurately but also the length of the lamp unit in the longitudinal direction of a vehicle can be made short.

According to the aforesaid configuration, although the configuration of “the light emitting element” is not limited to a particular one as described above, when the light emitting element is configured to include a light emitting chip and a sealing resin for sealing the light emitting chip and further to integrally form the sealing resin with the translucent member, the configuration of the lamp unit can be simplified. In this case, as a mode at the time of “integrally forming” the sealing resin with the translucent member, there may be employed a mode in which the sealing member is sealed by the translucent member or a mode in which the light emitting chip is directly sealed by the translucent member thereby to make the translucent member also have a function of sealing resin, for example.

In the aforesaid arrangement, when the “reflecting surface” of the translucent member is formed by a hyperboloid of revolution, all the light reflected from the inner surface of the reflecting surface can be irradiated as spread light from the virtual image position of the light emitting element. Thus, the refraction control of the light reflected by the inner surface of the irradiating surface can be facilitated.

In this case, when the “irradiating surface” of the translucent member is formed by an ellipsoid of revolution, all the light irradiated from the irradiating surface in the forward direction of the lamp unit can be made substantially parallel rays, a spot-shaped distribution pattern can be obtained. In this case, when the light irradiated from the translucent member in the forward direction is subjected to a suitable spread and deflection control by using a lens etc., a desired light distribution pattern can be obtained easily.

In the aforesaid configuration, when substantially entire area of the surface of the translucent member is configured by the reflecting surface and the irradiating surface, the utilization factor of lights from the light emitting element can be enhanced to almost the maximum degree.

Additionally, a lamp for a vehicle is provided, comprising a plurality of lamp units housed in a lamp chamber. The plurality of lamp units include a first lamp unit of a projector type, including a substantially transparent projection lens on an optical axis, a first light emitting element positioned at a rear side of said projection lens, and a reflector covering an upper side of said first light emitting element to direct emitted light in a forward direction toward said projection lens. These lamp units also include at least one second lamp unit comprising a second light emitting element that directs light backwards to a translucent member having a reflecting surface that receives and reflects said emitted light from the second light emitting element towards an irradiating surface of said translucent member and in a forward direction of the lamp unit.

Further, a lamp for a vehicle is provided, said lamp comprising a plurality of lamp units housed in a lamp chamber. The plurality of lamp units include a first lamp unit of a projector type, including a substantially transparent projection lens on an optical axis, a first light emitting element positioned at a rear side of said projection lens, and a reflector covering an upper side of said first light emitting element to direct emitted light in a forward direction toward said projection lens. Also, the lamp units include a plurality of second lamp units, each comprising a second light emitting element that directs light backwards to a translucent member having a reflecting surface that receives and reflects said emitted light from the second light emitting element towards an irradiating surface of said translucent member and in a forward direction of the lamp unit. The second type of lamp units include a first one of said second lamp units having a concave shape of said reflecting surface and formed by a hyperbola such that a virtual image of light is formed at a focal point of a hyperboloid of revolution that is conjugate with said reflecting surface, wherein said irradiating surface has a convex shape formed by an ellipse having an eccentricity that is reciprocal of a refractive index of the translucent member, a second one of said second lamp units, wherein said irradiating surface is a substantially elliptical cylindrical or cylindroid surface and said reflecting surface is substantially concave and formed by a hyperbola such that a virtual image of light is formed at a focal point of a hyperboloid of revolution that is conjugate with said reflecting surface, and a third one of said second lamp units, wherein wherein said irradiating surface is a substantially elliptical cylindrical or cylindroid surface and said reflecting surface is a substantially hyperbolic cylindrical surface.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an exemplary, non-limiting embodiment of the present invention will be explained with reference to the accompanying drawings.

FIG. 1is a front view showing an illumination lamp for a vehicle according to the exemplary, non-limiting embodiment of the present invention, andFIG. 2is a sectional diagram cut along a line II—II inFIG. 1.

An illumination lamp10for a vehicle according to the embodiment is a head lamp provided at the right side of the front end portion of a vehicle and is configured in a manner that lamp units30,50,60,70are housed within a lamp chamber formed by a lamp body12and a translucent cover14attached to the opening portion at the front end of the lamp body. For example, but not byway of limitation, the total number of lamp units30,50,60,70may be seven, but the present invention is not limited thereto.

The translucent cover14extends from the lower end portion thereof toward the upper end portion thereof at the rear side thereof. An inner panel16is provided along the translucent cover14within the lamp chamber. Cylindrical opening portions16a,16b,16cand16dsurround the lamp units30,40,50,60and70at the positions corresponding to these lamp units of the inner panel16, respectively.

The lamp units30,40,50,60and70are inclinable in the vertical and horizontal directions by the lamp body12through an aiming mechanism22that is attached to a common unit supporting member20.

The unit supporting member20is configured by die-cast parts and is provided with a vertical panel portion20A, unit attachment portions20B1,20B2,20B3extending like shelves in the forward direction at plural portions of the vertical panel portion20A, and a heat sink portion20C formed by a plurality of radiation fins extending backward from the vertical panel portion20A to a position exposed to the external space of the lamp.

In the illumination lamp10for a vehicle according to the embodiment, a low-beam light distribution pattern is formed by lights irradiated from the lamp units30,50,60and70.

Among the lamp units30,50,60and70, the lamp units30(e.g., four, but not limited thereto) positioned at a lower stage are lamp units for radiating lights that form the basic low-beam light distribution pattern. The three lamp units50,60and70positioned at an upper stage are lamp units for radiating lights to reinforce the basic light distribution pattern. In this case, among the three lamp units50,60and70positioned at the upper stage, the lamp unit50at the center position is a lamp unit for forming a light distribution pattern for converging light, the lamp unit60on the inner side in the vehicle width direction is a lamp unit for forming a light distribution pattern for middle area distribution, and the lamp unit70on the outer side in the vehicle width direction is a lamp unit for forming a light distribution pattern for wide area distribution.

The four lamp units30for forming the basic light distribution pattern are arranged such that optical axes Ax1thereof extend in a direction substantially orthogonal to the vertical panel portion20A so as to be parallel from one another. The optical axes Ax1of the respective lamp units30extend downward by substantially 0.5 to 0.6 degrees with respect to the longitudinal direction of a vehicle when the optical axis adjusting process using the aiming mechanism22is completed. On the other hand, the optical axes Ax2of the remaining three lamp units50,60and70are directed downward slightly with respect to the optical axes Ax1of the lamp units30.

Next, the configurations of the lamp units30,50,60and70will be explained. First, the configuration of the lamp units30for forming the basic light distribution pattern will be explained.

FIG. 3is a side sectional diagram showing the lamp unit30in detail. The lamp unit30is a projector type lamp unit and is provided with a projection lens32disposed on the optical axis Ax1, a light emitting element34disposed at the rear side of the projection lens32, a reflector36disposed to cover the light emitting element34from the upper side thereof, and a straight traveling preventing member38disposed between the light emitting element34and the projection lens32.

The projection lens32is made of transparent resin and is configured by a plane-convex lens having a front side surface that is formed as a convex plane and rear side surface that is formed as a plane.

The light emitting element34is a white light emitting diode having a light emitting chip34aof a substantially 0.3 to 1.0 mm square. The light emitting element is fixed on the unit attachment portion20B1of the unit supporting member20through a plate40such that the light emitting chip34ais disposed upward so as to be directed vertically on the optical axis Ax1.

The reflector36is configured to reflect the light emitted from the light emitting element34in the forward direction so as to close to the optical axis Ax1to substantially focus the reflected light near the backward side focusing point F of the projection lens32. The reflection surface36aof the reflector36is set such that the sectional shape including the optical axis Ax1is substantially elliptical shape and the eccentricity becomes larger gradually from the vertical section toward the horizontal section. The reflection surface36ais arranged to substantially focus the light emitted from the light emitting element34at a position slightly forward of the backward side focusing point F. The reflector36is fixed at its peripheral lower end portion to the unit attachment portion20B1of the unit supporting member20.

The straight traveling preventing member38is configured by a main body portion38A having its upper surface38aformed in a substantially L-shape when seen from the front side of the lamp. A lens holder portion38B extends forward from the front end portion of the main body portion38A.

The upper surface38aof the main body portion38A extends backward from the backward side focusing point F of the projection lens32. The left side area (the right side area when seen from the front side of the lamp) with respect to the optical axis Ax1is formed by a plane extending horizontally to the left direction from the optical axis Ax1, and the right side area with respect to the optical axis Ax1is formed by a plane extending in an inclined right downward direction (for example, downward by about 15 degrees) from the optical axis Ax1. The front end edge38a1of the upper surface38ais formed in a substantially arc shape along the focusing surface of the backward side focusing point F of the projection lens32.

The upper surface38ais subjected to mirror surface processing such as aluminum vapor deposition, such that the upper surface38ais a reflection surface. The main body portion38A is arranged in a manner that the upper surface38athereof prevents the straight traveling of a part of the reflection light from the reflection surface36aof the reflector36and reflect the part of the reflection light upward. The upper surface38ais fixed at its lower surface to the unit attachment portion20B1of the unit supporting member20.

The lens holder portion38B bends downward from the front end portion of the main body portion38A and extends forward thereby to support the projection lens32at the front end portion of the lens holder portion.

Next, the configuration of the lamp unit50for forming the converging light distribution pattern will be explained.FIG. 4is a detailed side sectional view showing the lamp unit50, andFIG. 5is a plan view thereof. The lamp unit50is configured by a light emitting element52, a translucent member54and a supporting bracket56.

The light emitting element52is a white light emitting diode having a light emitting chip52athat is substantially 0.3 to 1.0 mm square and the light emitting element is disposed to direct the light emitting chip52ain a slightly backward direction with respect to the vertically downward direction on an optical axis Ax2.

The translucent member54is a member made of transparent resin having a shape substantially similar to a bivalve and is disposed to cover the light emitting element52from the forward side thereof (that is, concerning the lamp unit50, cover the light emitting element from the slightly backward side with respect to the vertically downward direction). The translucent member54seals the light emitting chip52ain a manner that the light emitting chip52aof the light emitting element52is positioned at the upper portion of the front face of the translucent member.

The rear surface of the translucent member54is configured at its entirety as a reflecting surface54bwhich reflects, on the inner surface thereof, the light incident into the translucent member54from the light emitting element52. In order to realize such a function, the mirror surface processing such as aluminum vapor deposition is performed on the rear surface area of the translucent member54.

On the other hand, the front surface of the translucent member54is configured, at its entire region except for the attachment portion of the supporting bracket56, as an irradiating surface54awhich emits light, irradiated from the light emitting element52and then reflected by the inner surface of the reflecting surface54b, in the forward direction of the lamp unit from the translucent member54.

The reflecting surface54bof the translucent member54is set, at its vertical sectional shape including the optical axis Ax2of the lamp unit50, to a concavely curved shape formed by a hyperbola H having its focusing point at the light emitting center A of the light emitting element52.

The reflecting surface54bis configured by a hyperboloid of revolution having a center axis Ax3which coincides with an axis line passing through the light emitting center A of the light emitting element52and extending in the inclined downward and backward direction. The virtual image of the light emitting element52(more specifically, the virtual image of the light emitting chip52a) is formed at the focusing point of a hyperboloid of revolution that is conjugate with the hyperboloid of revolution constituting the reflecting surface54b.

The virtual image position B of this virtual image is located at a position in the inclined downward and backward direction with respect to the light emitting center A of the light emitting element52. The reflecting surface54breflects by the inner surface thereof the light incident into the translucent member54from the light emitting element52as if the reflected light is a light spread from the virtual image position B of the light emitting chip52a.

On the other hand, the irradiating surface54aof the translucent member54is set, in its vertical sectional shape passing through the light emitting center A of the light emitting element52, to have a convexly curved shape formed by an ellipse E which focusing point is the virtual image position B of the light emitting element52.

The reflecting surface54bis configured by an ellipsoid of revolution or a spheroid having a center axis Ax4which coincides with an axis line extending parallel to the optical axis Ax2of the lamp unit50, and also has a focusing point on the backward side which coincides with the virtual image position B. In this case, the eccentricity e of the ellipsoid of revolution constituting the irradiating surface54ais set to a reciprocal of the refractive index n of the translucent member54(that is, e=1/n). Thus, the irradiating surface acts to irradiate the light, irradiated from the light emitting element52and then reflected by the inner surface of the reflecting surface54b, in the forward direction of the lamp unit from the irradiating surface54aas parallel rays along the optical axis Ax2.

The supporting bracket56is a member made of metal which extends in the longitudinal direction of a vehicle along the irradiating surface54aat the upper portion of the translucent member54and which fixedly supports the light emitting element52at the front end portion thereof. The lamp unit50is fixedly supported at its rear end portion by the unit attachment portion20B2of the unit supporting member20. In this case, the lamp unit50is positioned at and supported by the unit attachment portion20B3of the unit supporting member20at the rear surface of the translucent member54.

Next, the configuration of the lamp unit60for forming the middle-area light distribution pattern will be explained.FIG. 6is a detailed plan view of the lamp unit60. The lamp unit60is configured by a light emitting element62, a translucent member64and a supporting bracket66. The configurations of the light emitting element62and the supporting bracket66are substantially similar to the light emitting element52and the supporting bracket56of the lamp unit50.

The translucent member64is made of transparent resin like the translucent member54of the lamp unit50. The rear surface of this translucent member is configured as a reflecting surface64bwhich reflects, on the inner surface thereof, the light incident into the translucent member64from the light emitting element62. The front surface of this translucent member is configured as an irradiating surface64awhich emits light, irradiated from the light emitting element62and then reflected by the inner surface of the reflecting surface64b, in the forward direction of the lamp unit from the translucent member64.

The shape of the reflecting surface64bof the translucent member64is same as that of the reflecting surface54bof the translucent member54, whilst the shape of the irradiating surface64adiffers from that of the irradiating surface54aof the translucent member54.

That is, like the irradiating surface54aof the translucent member54, the irradiating surface64aof the translucent member64is set, in its vertical sectional shape passing through the light emitting center A of the light emitting element62, to have a convexly curved shape formed by an ellipse which focusing point coincides with the virtual image position B of the light emitting element62. Then, this irradiating surface is configured as an elliptic cylindrical or cylindroid surface in which such a vertical sectional shape is extended in the horizontal direction as it is. Thus, this irradiating surface acts so that the light, irradiated from the light emitting element62and then reflected by the inner surface of the reflecting surface64b, is irradiated from the irradiating surface64aas parallel rays along the optical axis Ax2as to the vertical direction, whilst, as to the horizontal direction, irradiated from the irradiating surface as spread light being spread to some extent in the horizontal direction around the optical axis Ax2.

Next, the configuration of the lamp unit70for forming the wide-area light distribution pattern will be explained.FIG. 7is a plan view showing the lamp unit70. The lamp unit70is configured by a light emitting element72, a translucent member74and a supporting bracket76.

The configurations of the light emitting element72and the supporting bracket76are same as the light emitting element62and the supporting bracket66of the lamp unit60.

The translucent member74is made of transparent resin like the translucent member64of the lamp unit60. The rear surface of this translucent member is configured as a reflecting surface74bwhich reflects, on the inner surface thereof, the light incident into the translucent member74from the light emitting element72. The front surface of this translucent member is configured as an irradiating surface74awhich emits light, irradiated from the light emitting element72and then reflected by the inner surface of the reflecting surface74b, in the forward direction of the lamp unit from the translucent member74.

The shape of the irradiating surface74aof the translucent member74is same as that of the irradiating surface64aof the translucent member64, whilst the shape of the reflecting surface74bdiffers from that of the reflecting surface64bof the translucent member64.

Like the reflecting surface64bof the translucent member64, the reflecting surface74bof the translucent member74is set, in its vertical sectional shape passing through the light emitting center A of the light emitting element72, to have a concavely curved shape formed by a hyperbola which focusing point coincides with the light emitting center A of the light emitting element72. Then, this irradiating surface is configured as a hyperbolic cylindrical surface in which such a vertical sectional shape is extended in the horizontal direction as it is.

Thus, the reflecting surface74breflects on the inner surface thereof the light incident into the translucent member74from the light emitting element72such that the light is reflected as spread light as if it is emitted from the virtual image position B of the light emitting element72as to the vertical direction, whilst, as to the horizontal direction, emitted as spread light which spreads in the horizontal direction around the optical axis Ax2to a larger extent as compared with the spread light emitted from the virtual image position B.

Accordingly, this irradiating surface acts such that the light, irradiated from the light emitting element72and then reflected by the inner surface of the reflecting surface74b, is irradiated from the irradiating surface74aas parallel rays along the optical axis Ax2as to the vertical direction, whilst, as to the horizontal direction, irradiated from the irradiating surface as spread light being spread to a large extent in the horizontal direction around the optical axis Ax2.

FIG. 8is a diagram showing the low-beam light distribution pattern formed on a phantom vertical screen disposed at a position about 25 m ahead of the lamp by light irradiated in the forward direction from the illumination lamp10for a vehicle according to the embodiment of the present invention.

The low-beam light distribution pattern PL is the light distribution pattern of the left distribution light and includes at its upper end edge a horizontal cut-off line CL1and a slanted cut-off line CL2which rises with an angle (for example, about 15 degrees, but not limited thereto) from the horizontal cut-off line CL1. An elbow point E which is a cross point between the both cut-off lines CL1and CL2is set at a position below by substantially 0.5 to 0.6 degree from a vanishing point H-V in the straight ahead of the lamp. In the low-beam light distribution pattern PL, a hot zone HZ as a high luminance area is formed to surround the elbow point E.

This low-beam light distribution pattern PL is formed as a composite light distribution pattern of four basic light distribution patterns P0formed in a superimposed manner at the substantially same position by the lights irradiated from the four lamp units30, a small-area light distribution pattern Pa1formed by the light irradiated from the lamp unit50, a middle-area light distribution pattern Pa2formed by the light irradiated from the lamp unit60and a large-area light distribution pattern Pa3formed by the light irradiated from the lamp unit70.

As shown inFIG. 9(a), in the basic light distribution pattern P0formed by the lights irradiated from the lamp units30, the horizontal and slanted cut-off lines CL1, CL2are formed as inverted projection images of the front end edge38a1of the upper surface38aof the main body portion38A in the straight traveling preventing member38. In this case, since the upper surface38aof the main body portion38A is formed as a reflection surface, as shown by two-dot chain lines inFIG. 3, the lights emitted upward from the projection lens32among the reflection lights from the reflection surface36aof the reflector36are also used as the lights emitted downward from the projection lens32as shown by steady lines in this figure due to the reflecting action of the upper surface38a. Thus, the utilization factor of light emitted from the light emitting element34can be enhanced, and the hot zone HZ is formed.

On the other hand, as shown inFIG. 9(b), the converging light distribution pattern Pa1formed by the light irradiated from the lamp unit50is a light distribution pattern formed as a projection image of the light emitting chip52aof the light emitting element52, and configured as a spot-shaped distribution pattern with substantially square configuration.

Further, as shown inFIG. 9(c), the middle-area light distribution pattern Pa2formed by the light irradiated from the lamp unit60is a light distribution pattern which is formed as a spread projection image of the light emitting chip62aof the light emitting element62and configured as a wide distribution pattern spread to some extent in the horizontal direction.

Furthermore, as shown inFIG. 9(d), the wide-area light distribution pattern Pa3formed by the light irradiated from the lamp unit70is a light distribution pattern which is formed as a spread projection image of the light emitting chip72aof the light emitting element72and configured as a wide distribution pattern spread to a large extent in the horizontal direction.

Each of the converging light distribution pattern Pa1, the middle-area light distribution pattern Pa2and the wide-area light distribution pattern Pa3is positioned at its upper end edge slightly below the horizontal cut-off line CL1. This is because the optical axis Ax2of each of the lamp units50,60,70is directed slightly downward with respect to the optical axis Ax1of the lamp unit30.

The illumination lamp10for a vehicle according to the embodiment is provided with the four kinds of the lamp units30,50,60, and70. The lamp units50,60,70among these lamp units are arranged such that the translucent members54,64,74are disposed to cover the light emitting elements52,62,72from the front sides thereof, respectively. Thus, the utilization factor of lights from the light emitting elements52,62,72can be enhanced.

In this case, the reflecting surfaces54b,64b,74bconstituting the rear surfaces of the translucent members54,64,74are set, in their vertical sectional shapes passing through the light emitting centers A of the light emitting elements52,62,72, each to have the concavely curved shape formed by the hyperbola H which focusing point coincides with the light emitting center A of the corresponding light emitting element, respectively. Thus, the reflecting surfaces54b,64b,74breflect on the inner surfaces thereof the lights incident into the translucent members54,64,74from the light emitting elements52,62,72such that the lights are reflected as spread lights as if they are emitted from the virtual image positions B of the light emitting chips52a,62a,72aof the light emitting elements52,62,72as to the aforesaid vertical sections, respectively.

Further, the irradiating surfaces54a,64a,74aconstituting the front surfaces of the translucent members54,64,74are set, in their aforesaid vertical sectional shapes, each to have the convexly curved shape formed by the ellipse E which focusing point coincides with the virtual image position B of the corresponding one of the light emitting chips52a,62a,72a, respectively. Thus, the irradiating surfaces54a,64a,74aact such that the lights, irradiated from the light emitting elements52,62,72and then reflected by the inner surfaces of the reflecting surfaces54b,64b,74b, are irradiated from the translucent members54,64,74in the forward direction of the lamp units as substantially parallel rays as to the aforesaid vertical sections, respectively.

Thus, the irradiation lights from the translucent members54,64,74can be controlled accurately despite setting the lengths of the translucent members54,64,74in the longitudinal direction of a vehicle to be substantially short.

In this manner, the utilization factor of lights from the light emitting elements52,62,72can be substantially enhanced, and not only the irradiation lights from the lamp units50,60,70can be controlled accurately, but also the lengths of the lamp units in the longitudinal direction of a vehicle can be made short.

In particular, since the eccentricities of the ellipses E constituting the irradiating surfaces54a,64a,74aare set to reciprocals 1/n of the refractive indexes n of the translucent members54,64,74, respectively, each of the lights irradiated from the translucent members54,64,74can be set to accurate parallel rays within the aforesaid vertical section and hence the irradiation lights can be controlled further accurately.

Further, in the translucent members54,64, since each of the reflecting surfaces54b,64bis configured by the hyperboloid of revolution, the lights reflected by the inner surfaces of the reflecting surfaces54b,64bare irradiated as spread lights from the virtual image positions B of the light emitting chips52a,62a, respectively. Thus, the refraction control of the lights reflected by the inner surfaces of the irradiating surfaces54a,64acan be facilitated.

In this case, the translucent member54is configured at its irradiating surface54aby the ellipsoid of revolution. All the lights irradiated in the forward direction of the lamp unit from the irradiating surface54acan be made as parallel rays, whereby a spot-shaped distribution pattern an be formed.

Further, the translucent members54,64,74are configured such that the vertical sectional shapes of these translucent members passing through the light emitting centers A of the light emitting elements52,62,72are maintained in the same shapes, whilst the horizontal shapes thereof are differentiated from one another, thereby forming the converging light distribution pattern Pa1, the middle-area light distribution pattern Pa2and the wide-area light distribution pattern Pa3, respectively. Thus, the basic light distribution pattern P0of the low-beam light distribution pattern PL can be reinforced without causing large unevenness of the light distribution on a road in the forward direction of a vehicle.

Additionally, since substantially entire areas of the surfaces of the translucent members54,64,74are configured by the reflecting surfaces54b,64b,74band the irradiating surfaces54a,64a,74b, respectively, the utilization factor of lights from the light emitting elements52,62,72can be enhanced to almost the maximum degree.

Further, since each of the translucent members54,64,74is configured to have a shape like a bivalve or a shape formed by slightly angulating a bivalve, which extends forwardly in an oblique downward direction. Thus, like the illumination lamp10for a vehicle according to the embodiment, even when the translucent cover14is formed to extend from the lower end portion thereof toward the upper end portion thereof at the rear side thereof, the lamp units50,60and70can be disposed without the lamp chamber without difficulty. Further, since each of the irradiating surfaces54a,64a,74aof the translucent members54,64,74has a vertical section of the elliptical shape, the translucent members can be matched with the curved shape of the translucent cover14. Thus, a sense of incongruity concerning the design can be eliminated.

Furthermore, since the translucent members54,64,74are configured also to have a function of the sealing resin for sealing the light emitting chips52a,62a,72aof the light emitting elements52,62,72, the configuration of each of the lamp units50,60,70can be simplified.

In the aforesaid embodiment, although the translucent members54,64,74are explained in a manner that the focusing points of the hyperbolas H constituting the vertical sectional shapes of the reflecting surfaces54b,64b,74bare positioned at the light emitting centers A of the light emitting elements52,62,72and that the focusing points of the ellipses E constituting the vertical sectional shapes of the irradiating surfaces54a,64a,74aare positioned at the virtual image positions B of the light emitting chips52a,62a,72a, respectively, the action and technical effects similar to those of the aforesaid embodiment can be obtained so long as the focusing point of the hyperbola H is positioned near the corresponding light emitting center A and the focusing point of the ellipse E is positioned near the corresponding virtual image position B.

Although the illumination lamp10for a vehicle according to the embodiment is configured to include the seven lamp units30,50,60,70, the total number of these respective lamp units may be set to another number.

Further, in the illumination lamp10for a vehicle according to the embodiment, the explanation is made that the basic light distribution pattern P0of the low-beam light distribution pattern PL is formed by the lights irradiated from the four projector type lamp units30. However, this basic light distribution pattern may be formed by using a lamp unit other than the lamp units30.

Although the illumination lamp10for a vehicle according to the embodiment is configured such that only the lamp units30,50,60,70for forming the low-beam light distribution pattern PL are housed within the lamp chamber, the lamp units for forming a high-beam light distribution pattern may also be housed within the same lamp chamber.

The illumination lamp10for a vehicle according to the embodiment is explained as the head lamp provided at the right side of the front end portion of a vehicle. However, even in the case where the illumination lamp for a vehicle according to the embodiment is used as a head lamp provided at the left side of the front end portion of a vehicle or as an illumination lamp for a vehicle other than the head lamp such as an adverse weather lamp or a fog lamp, the action and technical effects similar to those of the aforesaid embodiment can be obtained so long as the configuration similar to that of the aforesaid embodiment is employed.

FIG. 10is a front view showing a lamp unit110according to a first modified example andFIG. 11is a side sectional view thereof. The lamp unit110is configured by a light emitting element112, a translucent member114and a supporting bracket116.

The configuration of the light emitting element112itself is same as the light emitting element52of the lamp unit50of the aforesaid embodiment.

The translucent member114is made of transparent resin like the translucent member54of the lamp unit50, and the rear surface of the translucent member is configured as a reflecting surface114bwhich reflects, on the inner surface thereof, the light incident into the translucent member114from the light emitting element112, whilst the front surface of the translucent member is configured as an irradiating surface114awhich emits light, irradiated from the light emitting element112and then reflected by the inner surface of the reflecting surface114b, in the forward direction of the lamp unit from the translucent member114.

The surface configurations of the reflecting surface114band the irradiating surface114aof the translucent member114are substantially similar to the reflecting surface54band the irradiating surface54aof the translucent member54. However, the outer configuration of the reflecting surface and the irradiating surface of the translucent member114are substantially different from those of the reflecting surface and the irradiating surface of the aforesaid embodiment. Further, the arrangement of the light emitting element112differs from that of the light emitting element of the aforesaid embodiment.

In this modified example, the outer configuration of each of the reflecting surface114band the irradiating surface114ais set to a circle when seen from the front side, and the center axis Ax3of the hyperboloid of revolution constituting the reflecting surface114band the center axis Ax4of the ellipsoid of revolution constituting the irradiating surface114aare set as the same axis line passing through the center of the reflecting surface114band the irradiating surface114a. The light emitting element112is disposed at the center of the irradiating surface114a.

The supporting bracket116is a member made of metal which extends in the horizontal direction along the irradiating surface114aof the translucent member114and is arranged such that the light emitting element112is fixedly supported by the center portion of the supporting bracket and both end portions of the supporting bracket are coupled to and fixed to a metal supporting ring118disposed along the outer periphery of the irradiating surface114aof the translucent member114.

The lamp unit110according to this modified example is also arranged such that the light incident into the translucent member114from the light emitting element112is reflected by the inner surface of the reflecting surface114bof the translucent member114as spread light emitted from the virtual image position B of a light emitting chip112aand then irradiated from the irradiating surface114ain the forward direction of the lamp unit as parallel rays along the center axis Ax4.

Also, in the case of employing the configuration of this modified example, the utilization factor of light from the light emitting element112can be enhanced. Further, and not only can the irradiation light from the lamp unit110be controlled accurately, but also the length of the lamp unit in the longitudinal direction of a vehicle can be made short.

Next, the second modified example of the aforesaid embodiment will be explained.FIG. 12is a front view showing a lamp unit210according to this modified example, andFIG. 13is a side sectional view thereof.

As shown in these figures, the lamp unit210is configured by a light emitting element212, a translucent member214and a supporting bracket216.

The configuration of the light emitting element212itself is substantially similar to the light emitting element52of the lamp unit50of the aforesaid embodiment.

The translucent member214is made of transparent resin like the translucent member54of the lamp unit50, and the rear surface of the translucent member is configured as a reflecting surface214bwhich reflects, on the inner surface thereof, the light incident into the translucent member214from the light emitting element212, whilst the front surface of the translucent member is configured as an irradiating surface214awhich emits light, irradiated from the light emitting element212and then reflected by the inner surface of the reflecting surface214b, in the forward direction of the lamp unit from the translucent member214.

The surface configurations of the reflecting surface214band the irradiating surface214aof the translucent member214are partially the same as the reflecting surface54band the irradiating surface54aof the translucent member54. However, the outer configuration of the reflecting surface and the irradiating surface of the translucent member214are different from those of the reflecting surface and the irradiating surface of the aforesaid embodiment. Further, the number of each of the light emitting element212and the supporting bracket216differs from those of the light emitting element and the supporting bracket of the aforesaid embodiment.

That is, this modified example is arranged such that the lamp unit50of the aforesaid embodiment is disposed at four positions placed with an interval of 90 degrees therebetween around the center axis Ax4and the mutually overlapped portions of the translucent members54of the four lamp units50are integrated.

The supporting brackets216are fixedly supported at the respective tip end portions of a supporting frame218of a cross shape which is disposed near the rear side of the translucent member214. The supporting frame218is provided with projection portions218awhich position and support the translucent member214at four portions of the rear surface thereof.

The lamp unit210according to this modified example is also arranged in a manner that the light incident into the translucent member214from the light emitting element212is reflected by the inner surface of the reflecting surface214bof the translucent member214as spread light emitted from the virtual image position B of a light emitting chip212aand then irradiated from the irradiating surface214ain the forward direction of the lamp unit as parallel rays along the center axis Ax4.

Also, in the case of employing the configuration of this modified example, the utilization factor of light from the light emitting element212can be enhanced, and not only the irradiation light from the lamp unit210can be controlled accurately but also the length of the lamp unit in the longitudinal direction of a vehicle can be made short.

Further, when the lamp unit is configured with the four light emitting elements212as in this modified example, a sufficient amount of irradiation light can be secured.

Next, a third modified example of the aforesaid embodiment will be explained.FIG. 14is a front view showing a lamp unit310according to this modified example andFIG. 15is a side sectional view thereof. The lamp unit310is configured by a light emitting element312, a translucent member314and a supporting bracket316.

The configuration of the light emitting element312itself is same as the light emitting element52of the lamp unit50of the aforesaid embodiment.

The translucent member314is made of transparent resin like the translucent member54of the lamp unit50, and the rear surface of the translucent member is configured as a reflecting surface314bwhich reflects, on the inner surface thereof, the light incident into the translucent member314from the light emitting element312, whilst the front surface of the translucent member is configured as an irradiating surface314awhich emits light, irradiated from the light emitting element312and then reflected by the inner surface of the reflecting surface314b, in the forward direction of the lamp unit from the translucent member314.

In this case, the translucent member314is set in its outer configuration seen from the front side thereof to a semicircle of a bottom chord shape. Also, the light emitting element312is disposed upward on a portion near the rear end of the lower end plane314cof the translucent member.

The surface configuration of the irradiating surface314aof the translucent member314is substantially the same as that of the irradiating surface54aof the translucent member54. Further, although the surface configuration of the reflecting surface314bof the translucent member314is formed by a hyperboloid of revolution like the reflecting surface54bof the translucent member54, the eccentricity e of the reflecting surface314bis set to be smaller than that of the reflecting surface54bof the translucent member54. Furthermore, the center axis Ax3of the hyperboloid of revolution constituting the reflecting surface314band the center axis Ax4of the ellipsoid of revolution constituting the irradiating surface314aare set as the same axis line and the light emitting element312is disposed on this axis line.

In this modified example, since the incident angle of the light incident into the reflecting surface314bof the translucent member314from the light emitting element312becomes larger than the critical angle of the translucent member314as to the area of the reflecting surface other than an area314b1near the rear end thereof, the light is reflected by the inner surface of the reflecting surface in a total-reflection manner. Thus, the mirror surface processing for the rear surface of the translucent member314is performed only on the area314b1near the rear end of the reflecting surface314b.

The supporting bracket316is a member made of metal that extends in the longitudinal direction of a vehicle along the surface314cof the translucent member314and fixedly supports the light emitting element312at the front end portion of the supporting bracket.

The lamp unit310according to this modified example is also arranged such that the light incident into the translucent member314from the light emitting element312is reflected by the inner surface of the reflecting surface314bof the translucent member314as spread light emitted from the virtual image position B of a light emitting chip312aand then irradiated from the irradiating surface314ain the forward direction of the lamp unit as parallel rays along the center axis Ax4.

In the case of employing the configuration of this modified example, although the length of the translucent member314in the longitudinal direction of a vehicle becomes longer than those of the aforesaid embodiment and the aforesaid modified examples, the utilization factor of light from the light emitting element312can be enhanced and the irradiation light from the translucent member314can be controlled accurately.

Further, according to this modified example, since the surface of the translucent member314is subjected to the mirror surface processing only at the area314b1near the rear end of the reflecting surface314b, pure or crystal feeling can be provided to the translucent member314.