Projector-type headlight and configuration structure of resin projector lens thereof

Disclosed is a projector-type headlight that can include a light emitting device, a reflector having a reflection surface to reflect a light from the light emitting device forward, a projector lens to project the reflected light from the reflection surface forward, the projector lens being a resin molding, and a shade to form a light distribution pattern having a light-dark border line by blocking a part of the reflected light heading from the reflection surface to the projector lens. A gate trace can be formed in a circumference portion of the projector lens. The gate trace can be provided lower than a horizontal surface on which a light axis of the projector lens passes through, and at the same time can be provided in a state of being shifted either leftward or rightward from a vertical surface on which the light axis of the projector lens passes through.

This application claims the priority benefit under 35 U.S.C. §119 of Japanese Patent Application No. 2010-005747 filed on Jan. 14, 2010, which is hereby incorporated in its entirety by reference.

BACKGROUND

The presently disclosed subject matter relates to a projector-type headlight and a configuration structure of a resin projector lens thereof, and especially to a projector-type headlight comprising a projector lens which is a resin molding, and a configuration structure of the resin projector lens.

2. Description of the Related Art

Conventionally, in a projector-type headlight, a light source is provided at a first focal point of an ellipsoidal reflection surface of a reflector or in the vicinity of the first focal point, a shade is provided at a second focal point of the ellipsoidal reflection surface or in the vicinity thereof, and a projector lens is provided on a front side of the second focal point (for example, refer to Japanese Patent Application Laid-Open Publication No. 2008-103192). In such a projector-type headlight, a light emitted from the light source is reflected by the ellipsoidal reflection surface, the reflected light is focused at the second focal point, a part of the reflected light is blocked by the shade, and the reflected light which is not blocked by the shade is projected forward by the projector lens. Since the part of the reflected light is blocked by the shade, a light distribution pattern when two vehicles pass each other, that is, a low beam, is formed.

As a light source of the projector-type headlight, a semi-conductor light emitting device (for example, a light emitting diode), an electric discharge lamp (for example, a high intensity discharge (HID) lamp, a high pressure metal vapor discharge lamp, or the like), a halogen lamp, an incandescent lamp, or the like has been used. Because a wavelength spectrum of the electric discharge lamp, the halogen lamp, and the incandescent lamp contains a large amount of infrared elements, heat is absorbed by the projector lens and the projector lens comes to have a very high temperature. On the other hand, because light emitted from a semi-conductor light emitting device such as a light emitting diode does not contain infrared rays, the projector lens would not be heated to a high temperature.

Therefore, in a case where the electric discharge lamp or the like is used as the light source, the projector lens is molten if a resin molding is used as the projector lens, and due to this reason, a resin molding cannot be used for the projector lens. Meanwhile, in a case where a semi-conductor light emitting device is used as a light source, because of a reason that the light does not contain infrared rays, and the like, the projector lens would not molten even if the resin molding is used as the projector lens, and thus, one can use the resin molding for the projector lens.

Meanwhile, even in a case where the semi-conductor light emitting device is used as the light source, there is a possibility that the projector lens may be deformed due to the heat generated by the element itself or the like, even if the projector lens is not molten. If the projector lens is deformed, optical characteristics of the projector lens are changed and light distribution pattern may be negatively influenced.

SUMMARY

Therefore, one possible aspect of the presently disclosed subject matter is to provide an ability to reduce influence to the light distribution pattern even in a case where the projector lens is deformed.

According to an aspect of the presently disclosed subject matter, there is provided a projector-type headlight comprising:

a light emitting device;

a reflector having a reflection surface to reflect a light from the light emitting device forward;

a projector lens to project the reflected light from the reflection surface forward, the projector lens being a resin molding; and

a shade to form a light distribution pattern having a light-dark border line by blocking a part of the reflected light heading from the reflection surface to the projector lens, wherein

a gate trace is formed in a circumference portion of the projector lens, and wherein

the gate trace is provided lower than a horizontal surface on which a light axis of the projector lens passes through, and at the same time is provided in a state of being shifted either leftward or rightward from a vertical surface on which the light axis of the projector lens passes through.

According to another aspect of the presently disclosed subject matter, there is provided a configuration structure of a resin projector lens in a projector-type headlight, comprising:

a gate trace formed in a circumference portion of the resin projector lens, wherein

the gate trace is provided lower than a horizontal surface on which a light axis of the resin projector lens passes through, and at the same time is provided in a state of being shifted either leftward or rightward from a vertical surface on which the light axis of the resin projector lens passes through.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments for implementing the presently disclosed subject matter will be explained with reference to the drawings. Although the following embodiments include various technical features for implementing the presently disclosed subject matter, this does not limit the scope of the disclosed subject matter to the following scope and examples shown in the drawings.

Moreover, “up”, “down”, “front”, “rear”, “left”, and “right” in the following explanation respectively indicate “up”, “down”, “front”, “rear”, “left”, and “right” of a vehicle on which a projector-type headlight is mounted. Accordingly, direction of right and left is determined when seen from rear to front.

FIG. 1is a perspective view of a projector-type headlight1.FIG. 2is a vertical cross-sectional view of the projector-type headlight1.FIG. 3is a horizontal cross-sectional view of the projector-type headlight1. The projector-type headlight1includes a light emitting device10, a first reflector20, a second reflector30, a shade40, a projector lens50, a heat sink60, and the like.

If the projector-type headlight1is for left-hand traffic, left side is a driving lane while right side is an oncoming lane. If the projector-type headlight1is for right-hand traffic, right side is a driving lane while left side is an oncoming lane.

A light axis Ax of the projector lens50extends in front and rear directions. The shade40, the heat sink60, and the light emitting device10are provided behind the projector lens50.

The light emitting device10is mounted on a circuit substrate11, and the circuit substrate11is attached onto an upper surface of the heat sink60, so that the light emitting device10faces upper and diagonally backward. When the light emitting device10is seen planarly from diagonally backward and above, the light emitting device10is provided in a rectangular shape and the long sides of the light emitting device10are leveled off while they are parallel to each other in right and left directions. The light emitting device10is a light emitting diode, an inorganic electroluminescence element, an organic electroluminescence element, or other type of a semi-conductor light emitting device.

The first reflector20is provided so as to surround the light emitting device10from back of the light emitting device10to diagonally forward above, diagonally forward right, and diagonally forward left of the element. On a concave surface on the front side of the first reflector20, a reflection coating is formed by aluminum evaporation, silver coating, or the like, and the concave portion on the front side is a first reflection surface21. The first reflection surface21is shaped to have an oval surface. An oval surface means an ellipsoid of revolution having an axis stretching in front and rear directions as a rotation axis, a complex ellipsoid, or a free-form surface based thereon. The complex ellipsoid means one having an oval-shaped vertical cross-section and having a parabolic or oval-shaped horizontal cross-section (focal point distance of the oval shape of the vertical cross-section and focal point distance of the oval shape of the horizontal cross-section differ from each other). Moreover, the rotation axis of the first reflection surface21may extend horizontally in front and rear directions or may be inclined downward in rear direction with respect to the horizontal surface. In a case where the rotation axis of the first reflection surface21extends horizontally in front and rear directions, the rotation axis of the first reflection surface21may match the light axis Ax of the projector lens50or may be slightly shifted out of the light axis Ax.

Since the first reflection surface21is formed to have an oval shape, the first reflection surface21has a first focal point F1and a second focal point F2, which is provided closer to the front side than the first focal point F1. The light emitting device10is provided at the first focal point F1of the first reflection surface21, or in the vicinity thereof. The first reflection surface21reflects a light emitted from the light emitting device10and focuses the reflected light to the second focal point F2. Here, in a case where the first reflection surface21is formed to have a complex oval surface or a free-form surface based thereon, the second focal point F2means a focal line. The focal line extends horizontally in right and left directions while center portion in the right and left directions is curved to project backward.

The shade40is provided in a plate-like manner. The shade40is provided in a condition where one surface of the shade40faces front and the other surface of the shade40faces rear. The shade40is curved to project backward to correspond to a curvature of the projector lens. The shade40is provided between the projector lens50and the light emitting device10so that an upper periphery41of the shade40is positioned at the second focal point F2or in the vicinity thereof.

Of the upper periphery41of the shade40, a portion which is on a left side from the light axis Ax (hereinafter referred to as a left side upper periphery42) is formed to be horizontal, and a portion which is on a right side from the light axis Ax (hereinafter referred to as a right side upper periphery43) is formed to be horizontal, so that there exists unevenness between the left side upper periphery42and the right side upper periphery43. A portion44between the left side upper periphery42and the right side upper periphery43is inclined with respect to the horizontal direction (hereinafter referred to as an inclined portion44). In one example, an inclined angle of the inclined portion44is 15° or 45° with respect to the horizontal surface.

Of the upper periphery41of the shade40, a portion closer to the driving lane side from the light axis Ax is set higher than the portion closer to the oncoming lane side.

Specifically, in a case where the projector-type headlight1is for left-hand traffic, the left side upper periphery42of the shade40is positioned higher than the right side upper periphery43and the inclined portion44is inclined diagonally right down. In a case where the projector-type headlight1is for left-hand traffic, vertical position of the left side upper periphery42is slightly higher than the light axis Ax and vertical position of the right side upper periphery43approximately matches that of the light axis Ax.

Meanwhile, in a case where the projector-type headlight1is for right-hand traffic, the right side upper periphery43of the shade40is positioned higher than the left side upper periphery42and the inclined portion44is inclined diagonally left down. In a case where the projector-type headlight1is for right-hand traffic, vertical position of the right side upper periphery43is slightly higher than the light axis Ax and vertical position of the left side upper periphery42approximately matches that of the light axis Ax.

The second reflector30extends from the upper periphery of the shade40toward rear. A reflection coating is formed on an upper surface of the second reflector30by aluminum evaporation, silver coating, or the like, and the upper surface of the second reflector30is the second reflection surface31. The second reflection surface31is a surface obtained by moving a line along the upper periphery41of the shade40horizontally rear in a parallel manner. Therefore, the second reflection surface31is configured by: a horizontal plain surface32obtained by moving the left side upper periphery42horizontally rear in a parallel manner; a horizontal plain33obtained by moving the right side upper periphery43horizontally rear in a parallel manner; and a plain surface34obtained by moving the inclined portion44horizontally rear in a parallel manner. The second reflection surface31reflects a light reflected by the first reflection surface21forward.

The projector lens50is provided in front of the shade40. The projector lens50is a convex lens. The projector lens50is provided so that a focal point of the projector lens50is positioned at the second focal point F2of the reflection surface21or in the vicinity thereof. Moreover, the upper periphery41of the shade40is positioned at the focal point of the projector lens50or in the vicinity thereof.

FIG. 4is a front elevational view of the projector lens50in a case where the projector-type headlight1is for left-hand traffic.FIG. 5is a front elevational view of the projector lens50in a case where the projector-type headlight1is for right-hand traffic. As shown inFIGS. 1 to 5, the projector lens50includes a lens main body part51and a flange part52which protrudes from a circumference of the lens main body part51to outside of radial direction. An incidence surface53on back side of the lens main body part51has a concave surface which is not spherically shaped, and an exit surface54on the front side of the lens main body51has a concave surface which is not spherically shaped. Here, the projector lens50may be either a plane-convex lens or a meniscus convex lens.

A boss receiver55is respectively provided to both right and left sides of the flange part52.

Meanwhile, a cylindrical lens holder70is provided in front of the shade40. The lens holder70is provided so that shaft center of the lens holder70matches the front and rear directions, and front and rear portions of the lens holder70are opened. Boss71is respectively provided in a convex manner to both right and left sides of the front edge surface of the lens holder70. The projector lens50is attached to the front edge of the lens holder70in a manner that the projector lens50shuts the front side aperture of the lens holder70. Here, the flange part52of the projector lens50comes into contact with the front edge surface of the lens holder70, and the boss71is fitted into the boss receiver55.

The projector lens50is formed by mold injection by use of a thermal plastic resin having transparency, such as methacrylate resin (PMMA), polycarbonate resin (PC), or cycloolefin resin. Here, a cavity for the projector lens50is provided to a mold for forming the projector lens50, and a gate for injecting resin into the cavity is extended from the circumference portion of the cavity (a portion corresponding to the flange part52) to a radial direction. Therefore, a gate trace56is formed on the circumference portion of the projector lens50(circumference portion of the flange part52). A gate trace is a trace where a gate portion of a molded article was cut, or in other words, the resin or other material located at a position at which the resin or other material entered a mold via an injection port to form the molded structure, and the location or residual structure where the molded structure is eventually broken free from the resin located in the injection port runner after solidification of the resin or other molding material.

The gate trace56is positioned lower than the horizontal surface on which the light axis Ax passes through (i.e., lower than a horizontal plane in which the light axis Ax is completely located in). Moreover, the gate trace56is positioned closer to the driving lane side than the vertical surface on which the light axis Ax passes through (i.e., closer to the driving lane side than a vertical plane in which the light axis Ax is completely located in). Here, as shown inFIG. 4, in a case where the projector-type headlight1is for left-hand traffic, the gate trace56is shifted leftward from the vertical surface on which the light axis Ax passes through. Specifically, the gate trace56is shifted leftward by 20° to 60° around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark. The gate trace56can be shifted by 40° leftward.

Meanwhile, in a case where the projector-type headlight1is for right-hand traffic, the gate trace56is shifted rightward from the vertical surface on which the light axis Ax passes through, as shown inFIG. 5. Specifically, the gate trace56is shifted rightward by 20° to 60° around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark. The gate trace56can be shifted by 40° rightward.

In the projector-type headlight1, a light emitted from the light emitting device10is reflected forward by the first reflection surface21, and the reflected light is focused to the second focal point F2. Part of the reflected light is blocked by the shade40. Moreover, part of the reflected light is not blocked by the shade40and is incident into the projector lens50. Further, part of the reflected light is reflected by the second reflection surface31, and the reflected light reflected by the second reflection surface31is incident into the projector lens50. The reflected light which is not blocked is projected forward by the projector lens50. Thus, a light distribution pattern P1shown inFIG. 6or a light distribution pattern P2shown inFIG. 7is formed forward.

The light distribution patterns of the projector-type headlight1will be explained with reference toFIGS. 6 and 7.FIG. 6is a schematic view showing a light distribution pattern formed by the projector-type headlight1on the virtual screen set forward with a predetermined distance in a case where the projector-type headlight1is for left-hand traffic.FIG. 7is a schematic view showing a light distribution pattern formed by the projector-type headlight1on the virtual screen set forward with a predetermined distance in a case where the projector-type headlight1is for right-hand traffic. InFIGS. 6 and 7, a line H indicates a line of intersection of the horizontal surface on which the light axis Ax passes through and the virtual screen, and a line V indicates an intersection of the vertical surface on which the light axis Ax passes through and the virtual screen.

In a case where the projector-type headlight1is for left-hand traffic, as shown inFIG. 6, a light distribution pattern P1having a cut-off line for separating a bright part and a dark part (light-dark borderline) on an upper periphery of the bright part is formed. In the light distribution pattern P1, the cut-off line on the upper periphery of the bright part includes: a driving lane side horizontal cut-off line CL1which is on left side of the line V; an oncoming lane side horizontal cut-off line CL2which is on right side of the line V; and a diagonal cut-off line CL3which is diagonally leftward-upward from a left edge of the oncoming lane side horizontal cut-off line CL2. The driving lane side horizontal cut-off line CL1is formed approximately along the line H, while the oncoming lane side horizontal cut-off line CL2is formed in a position lower than the line H. The driving lane side horizontal cut-off line CL1is formed by the right side upper periphery43of the shade40. The oncoming lane side horizontal cut-off line CL2is formed by the left side upper periphery42of the shade40. The diagonal cut-off line CL3is formed by the inclined portion44of the shade40.

In a case where the projector-type headlight1is for right-hand traffic, as shown inFIG. 7, a light distribution pattern P2having a cut-off line for separating a bright part and a dark part (borderline) on an upper periphery of the bright part is formed. In the light distribution pattern P2, the cut-off line on the upper periphery of the bright part includes: a driving lane side horizontal cut-off line CL4which is on right side of the line V; an oncoming lane side horizontal cut-off line CL5which is on left side of the line V; and a diagonal cut-off line CL6which is diagonally leftward-downward from a left edge of the driving lane side horizontal cut-off line CL4. The driving lane side horizontal cut-off line CL4is formed approximately along the line H, while the oncoming lane side horizontal cut-off line CL5is formed in a position lower than the line H. The driving lane side horizontal cut-off lane CL4is formed by the left side upper periphery42of the shade40. The oncoming lane side horizontal cut-off line CL5is formed by the right side upper periphery43of the shade40. The diagonal cut-off line CL6is formed by the inclined portion44of the shade40.

FIG. 8shows illuminance distribution in the incident surface53behind the projector lens50in a case where the projector-type headlight1is for left-hand traffic. Since the left side upper periphery42of the shade40is positioned higher than the right side upper periphery43, with regard to an area where light is blocked by the shade40, left side part of the shade40is wider in upper direction than right side part. Therefore, as shown inFIG. 8, illuminance in left lower part of the projector lens50is lower than the other parts.

Here, when the projector-type headlight1is used for a long period of time, the projector lens50is deformed in the gate trace56the most, and the gate trace56is provided left lower portion. Due to this, left lower part of the incident surface53or the exit surface54is also deformed the most. Therefore, optical characteristics of the projector lens50are changed and the light distribution pattern P1is influenced by the change. However, as shown inFIG. 8, since the illuminance at the left lower part of the projector lens50is lower than the other parts, even if the left lower part of the incident surface53or the exit surface54is deformed, influence to the light distribution pattern P1can be reduced.

In a case where the projector-type headlight1is for right-hand traffic, since the gate trace56is provided at right lower portion, even if right lower part of the incident surface53or the exit surface54is deformed, illuminance in the right lower part of the projector lens50is lower than the other parts. Therefore, it becomes possible to reduce influence to the light distribution pattern P2. Here, in a case where the projector-type headlight1is for right-hand traffic, the illuminance distribution of the incident surface53behind the projector lens50is a minor-reversed version of the illuminance distribution shown inFIG. 8.

It is conceivable that follows are reasons why the projector lens50, which is a resin molding, is heated by the heat of the light emitting device10and is most easily deformed in the vicinity of the gate trace56.

When the projector lens50is injection-molded, high temperature resin flows through the gate and therefore, when the lens is cooled after molding, the gate portion of the molding is cooled at the end of the process. Then, the largest residual stress/residual strain is generated at the gate part. If the projector lens50is heated when being used, external deformation due to the residual stress/residual strain appears and as a result thereof, the lens is most easily deformed in the vicinity of the gate trace56which includes the residual stress/residual strain the most.

Hereinafter, embodiments of the presently disclosed subject matter will be explained.

The virtual screen set forward with a predetermined distance from the projector-type headlight1is illuminated by the projector-type headlight1to measure illuminance on the virtual screen. Illuminance distribution obtained as a result thereof is shown in iso-illuminance diagrammatic views inFIGS. 9A to 9C.FIG. 9Ais a result of a case where the projector-type headlight1is for left-hand traffic and an unused and unheated projector lens50which was mold injected is used.FIGS. 9B and 9Care results of cases where mold injected projector lens50was heated to 120° C., cooled to room temperature, and used as the projector lens50of the projector-type headlight1for left-hand traffic. InFIG. 9B, the gate trace56of the projector lens50is not shifted out of the vertical surface on which the light axis Ax passes through and shows a result when the gate trace56is positioned right below the light axis Ax (comparative example).FIG. 9Cshows a result in a case where the gate trace56is shifted by 40° leftward around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark (example).

FIG. 10is an iso-illuminance diagrammatic view obtained by subtracting the illuminance ofFIG. 9Cfrom the illuminance ofFIG. 9Bat one same point inFIGS. 9B and 9C.

It is evident fromFIGS. 9A to 9Cand10that the illuminance inFIG. 9Bis lower than the illuminance inFIG. 9Cin a side upper than the line H in the driving lane side from the line V. Therefore, it is understood that glare occurs more easily in a case where the gate trace56is positioned right below the light axis Ax (the case ofFIG. 9B). On the other hand, it is understood that glare does not easily occur in a case where the gate trace56is shifted by 40° leftward around the light axis Ax (the case ofFIG. 9C).

Illuminance in ZONE III according to No. 112 of ECE standards was measured in a case where the projector-type headlight1is for left-hand traffic and position of the projector lens50around the light axis Ax (the projector lens50was heated up to 120° C. and cooled to room temperature) was changed. Result of the measurement is shown inFIG. 11. InFIG. 11, horizontal axis indicates rotation angle of the gate trace56around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark, and vertical axis indicates illuminance of the zone III.

According to No. 112 of the ECE standards, a product does not meet the standards if illuminance in the ZONE III is 0.7 [1×] or more. As evident fromFIG. 11, it is understood that a margin of 20% or more of standards cannot be ensured, in a case where the gate trace56is provided right below the light axis Ax and the rotation angle of the gate trace56around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark is zero. On the other hand, it is understood that a margin of 20% or more of standards can be ensured, in a case where the gate trace56is shifted by 20° to 60° leftward around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark. Therefore, it is understood that if the gate trace56is shifted by 20° to 60° leftward around the light axis Ax with the vertical surface on which the light axis Ax passes through being given as a benchmark, glare does not easily occur.

According to an aspect of an exemplary embodiment of the presently disclosed subject matter, there is provided a projector-type headlight comprising:

a light emitting device;

a reflector having a reflection surface to reflect a light from the light emitting device forward;

a projector lens to project the reflected light from the reflection surface forward, the projector lens being a resin molding; and

a shade to form a light distribution pattern having a light-dark border line by blocking a part of the reflected light heading from the reflection surface to the projector lens, wherein

a gate trace is formed in a circumference portion of the projector lens, and wherein

the gate trace is provided lower than a horizontal surface on which a light axis of the projector lens passes through, and at the same time is provided in a state of being shifted either leftward or rightward from a vertical surface on which the light axis of the projector lens passes through.

The shade can be provided between the light emitting device and the projector lens so that an upper periphery of the shade is positioned at a focal point of the projector lens or in a vicinity of the focal point, wherein

a portion of the upper periphery of the shade which is closer to a driving lane side from the light axis of the projector lens is set higher than a portion in an oncoming lane side, and wherein

the gate trace is provided closer to the driving lane side than the vertical surface on which the light axis of the projector lens passes through.

The gate trace can be shifted either leftward or rightward by 20° to 60° around the light axis with the vertical surface on which the light axis of the projector lens passes through being given as a benchmark.

The gate trace can be shifted either leftward or rightward by 40° around the light axis with the vertical surface on which the light axis of the projector lens passes through being given as a benchmark.

According to another aspect of an exemplary embodiment of the presently disclosed subject matter, there is provided a configuration structure of a resin projector lens in a projector-type headlight, comprising:

a gate trace formed in a circumference portion of the resin projector lens, wherein

the gate trace is provided lower than a horizontal surface on which a light axis of the resin projector lens passes through, and at the same time is provided in a state of being shifted either leftward or rightward from a vertical surface on which the light axis of the resin projector lens passes through.

According to the embodiment of the presently disclosed subject matter, although the projector lens is most easily deformed in the vicinity of a gate trace, because the gate trace is provided lower than a horizontal surface on which a light axis passes through, and the gate trace is provided in a state of being shifted leftward or rightward from a vertical surface on which the light axis passes through, illuminance in a portion which is easily deformed can be reduced. Therefore, it becomes possible to reduce influence to the light distribution pattern by the deformation of projector lens.

The entire disclosure of Japanese Patent Application No. 2010-005747 filed on Jan. 14, 2010 including description, claims, drawings, and abstract are incorporated herein by reference in its entirety.

Although various exemplary embodiments have been shown and described, the invention is not limited to the embodiments shown. Therefore, the scope of the invention is intended to be defined solely by the scope of the claims that follow.