EP2351963A1

EP2351963A1 - Lighting device for vehicle

Info

Publication number: EP2351963A1
Application number: EP09827444A
Authority: EP
Inventors: Takayuki Yagi
Original assignee: Koito Manufacturing Co Ltd
Current assignee: Koito Manufacturing Co Ltd
Priority date: 2008-11-20
Filing date: 2009-10-09
Publication date: 2011-08-03
Anticipated expiration: 2029-10-09
Also published as: EP2351963A4; WO2010058663A1; JP5179328B2; EP2351963B1; JP2010123447A

Abstract

In a direct projector type vehicle lamp 10 using a rectangular light emitting surface 12A as a light source, the bottom edge of the light emitting surface 12A is arranged such that it extends along the horizontal line that is perpendicular to the optical axis Ax and such that the point O on the bottom edge is placed on the optical axis Ax. The rear surfaces of first and third lens regions Z1, Z3 of the lens 14 are formed with a Fresnel lens on the basis of the first reference line L1 and the rear surfaces of second and fourth lens regions Z2, Z4 of the lens 14 are formed with a Fresnel lens on the basis of a second reference line L2, thereby forming a horizontal cutoff line. An end portion of each of the lens regions Z1-Z4 is configured as an extended area Zla-Z4a which extends into the adjacent lens region, thereby forming an oblique cutoff line.

Description

TECHNICAL FIELD

The present invention relates to a vehicle lamp using a light emitting device such as a light emitting diode as a light source, and more particularly, the invention relates to a vehicle lamp configured to project light to form a low beam light distribution pattern having horizontal and oblique cutoff lines along an upper end portion.

BACKGROUND ART

In recent years, increasing number of light emitting devices such as light emitting diodes are being used as light sources of vehicle lamps.
For example, JP 2005-44683 A discloses a so-called direct projector type vehicle lamp having a convex lens disposed on the optical axis extending in the front-rear direction of the lamp and a light emitting device disposed adjacent to the rear focal point of the convex lens, and configured to deflect and control direct light from the light emitting device using the convex lens.
In the vehicle lamp disclosed in JP 2005-44683 A , a light distribution pattern having a horizontal cutoff line or an oblique cutoff line along its upper end portion is formed by blocking a portion of the direct light from the light emitting device, using a shade disposed right in front of the light emitting device.

PRIOR ART DOCUMENT

PATENT DOCUMENT

Patent document 1: JP 2005-44683 A

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

By employing the configuration of the vehicle lamp disclosed in JP 2005-44683 A , the lamp can be downsized. Further, in this vehicle lamp, a low beam light distribution pattern having horizontal and oblique cutoff lines along its upper end portion can be formed by suitably setting the shape of the top edge of the shade.
However, in the vehicle lamp disclosed in JP 2005-44683 A . a light flux from the light source cannot be efficiently used because a portion of the direct light from the light emitting device is blocked by the shade.
The present invention has been made in view of the above circumstance, and it is an object thereof to provide a direct projector type vehicle lamp using a rectangular light emitting surface as a light source, capable of forming a low beam light distribution pattern having horizontal and oblique cutoff lines along an upper end portion while improving efficiency of utilizing light flux from the light source.

MEANS FOR SOLVING THE PROBLEM

The present invention is devised with respect to an arrangement of the light source and a lens configuration to achieve the object described above.
That is, a vehicle lamp according to the invention has a light source disposed adjacent to an optical axis extending in a front-rear direction of the lamp, and a lens disposed in front of the light source to deflect and to forwardly project light from the light source, and is characterized in that:

the light source has a light emitting surface to rectangularly emit light when observed from a front of the lamp, and disposed such that a bottom edge of the light emitting surface extends along a horizontal line that is perpendicular to the optical axis and such that the optical axis intersects the bottom edge,
the lens includes, around the optical axis, a first lens region disposed primarily as an upper portion on a side of the own vehicle lane, a second lens region disposed primarily as an upper portion on a side of the opposing traffic lane, a third lens region disposed primarily as a lower portion on the side of the opposing traffic lane, and a fourth lens region disposed primarily as a lower portion on the side of the own vehicle lane,
rear surfaces of the first and third lens regions are formed with a plurality of annular zonal prisms in a concentric manner around a first reference line as a center, the annular zonal prisms having a serrated cross section along a plane including the first reference line, the first reference line passing through a first corner point at a top corner of the light emitting surface on the side of the own vehicle lane and extending parallel to the optical axis,
the annular zonal prisms are configured as a reflective Fresnel lens such that each of the annular zonal prisms refracts light emitted from the first corner point by an inner circumferential surface of the annular zonal prism in a direction away from the first reference line to cause the light to enter the annular zonal prism and such that the entered light is then totally reflected toward the front by an outer circumferential surface of the annular zonal prism,
rear surfaces of the second and fourth lens regions are formed with a plurality of annular zonal prisms in a concentric manner around a second reference line as a center, the annular zonal prisms having a serrated cross section along a plane including the second reference line, the second reference line passing through a second corner point at a bottom corner of the light emitting surface on the side of the opposing traffic lane and extending parallel to the optical axis,
the annular zonal prisms are configured as a reflective Fresnel lens such that each of the annular zonal prisms refracts light emitted from the second corner point by an inner circumferential surface of the annular zonal prism in a direction away from the second reference line to cause the light to enter the annular zonal prism and such that the entered light is then totally reflected toward the front by an outer circumferential surface of the annular zonal prism,
at least one of an end portion of the first lens region adjacent to the second lens region, an end portion of the second lens region adjacent to the third lens region, an end portion of the third lens region adjacent to the fourth lens region, and an end portion of the fourth lens region adjacent to the first lens region, is formed as a fan-shaped extended area extending into the adjacent lens region by a predetermined angle, and
a front surface of a general area of each of the first to fourth lens regions other than the extended area is formed with a plurality of horizontally diffusing elements to horizontally diffuse light exiting from the general area.

The "light source" is not particularly limited in its shape or size as long as it is configured to provide a light emitting surface to rectangularly emit light when observed from the front of the lamp. Its manner of light emission is not limited either. For example, there may be employed a light emitting chip of a light emitting device such as a light emitting diode, a light exit surface of a light guide through which light from a primary light source is guided, or a window portion where a bulb of a discharge lamp is coated with a light shield paint expect for the window portion.
With regard to the "slight emitting surface to rectangularly emit light", the right and left side edges of the light emitting surface need not extend perpendicularly to the top edge and the bottom edge as long as the top edge and the bottom edge extend parallel to each other. For example, the light emitting surface may have a parallelogrammic shape or a trapezoidal shape.
The "extended area" is not particularly limited in its shape or size as long as it is formed as a fan-shaped area that extends into the adjacent lens region by a predetermined angle. A specific value of the "predetermined angle" is set in accordance with the shape of the light emitting surface, an inclination angle of the oblique cutoff line, etc.
The horizontal diffusion of the light exiting from the general area by the "plurality of horizontally diffusing elements" may be an equal diffusion to the right and left sides or a diffusion to the right and left sides at different diffusion angles.

ADVANTAGES OF THE INVENTION

The vehicle lamp according to the invention is configured such that the light from the light source disposed adjacent to the optical axis extending in the front-rear direction of the lamp is deflected and projected forward by the lens disposed in front of the light source. The rear surface of the lends 14 is formed with the reflective Fresnel lenses, and therefore, the lamp can be made compact.
Further, in the vehicle lamp according to the invention, the light source has the light emitting surface which rectangularly emits light when observed from the front of the lamp, and is disposed such that its bottom edge extends along a horizontal line that is perpendicular to the optical axis and such that a point on the bottom edge is positioned on the optical axis. The lens includes, with respect to the optical axis, the first lens region disposed primarily as the upper portion on the own vehicle lane side, the second lens region disposed primarily as the upper portion on the opposing traffic lane side, the third lens region disposed primarily as the lower portion on the opposing traffic lane side, and the fourth lens region disposed primarily as the lower portion on the own vehicle lane side. The rear surfaces of the first and third lens regions and the rear surfaces of the second and fourth lens regions are formed with the reflective Fresnel lenses on the basis of the different reference lines respectively. Therefore, the following effects can be obtained.
That is, the rear surfaces of the first and third lens regions are formed with the plurality of annular zonal prisms that are concentric around the first reference line as the center. The annular zonal prisms have the serrated cross section along the plane including the first reference line which passes through the first corner point at the top corner of the light emitting surface on the side of the own vehicle lane and extends parallel to the optical axis. The annular zonal prisms are configured as a reflective Fresnel lens such that each of the annular zonal prisms refracts light emitted from the first corner point by an inner circumferential surface of the annular zonal prism in a direction away from the first reference line to cause the light to enter the annular zonal prism and such that the entered light is then totally reflected toward the front by an outer circumferential surface of the annular zonal prism. Therefore, light exiting from the first and third lens regions are horizontally diffused by the plurality of horizontally diffusing elements formed in the front surfaces of their general areas, whereby a horizontally diffused light distribution pattern having a horizontal cutoff line along the upper end portion can be formed.
On the other hand, the rear surfaces of the second and fourth lens regions are formed with the plurality of annular zonal prisms that are concentric with the second reference line as the center. The annular zonal prisms have a serrated cross section along the plane including the second reference line which passes through the second corner point at the bottom corner of the light emitting surface on the side of the opposing traffic lane and extends parallel to the optical axis. The annular zonal prisms are configured as a reflective Fresnel lens such that each of the annular zonal prism refracts light emitted from the second corner point by an inner circumferential surface of the annular zonal prism in a direction away from the second reference line to cause the light to enter the annular zonal prism and such that the entered light is totally reflected toward the front by an outer circumferential surface of the annular zonal prism. Therefore, light exiting from the second and fourth lens regions are horizontally diffused by the plurality of horizontally diffusing elements formed on the front surfaces of their general areas, whereby a horizontally diffused light distribution pattern having a horizontal cutoff line along the upper end portion can be formed.
The reflective Fresnel lens of the rear surfaces of the first and third lens regions is formed on the basis of the first reference line, and the reflective Fresnel lens of the rear surfaces of the second and fourth lens regions are formed on the basis of the second reference line. Therefore, the horizontal cutoff line of the horizontally diffused light distribution pattern formed by the light exiting from the first and third lens regions and the horizontal cutoff line of the horizontally diffused light distribution pattern formed by the light exiting from the second and fourth lens regions can substantially be aligned at the same position in the up-down direction.
In addition, in the vehicle lamp according to the invention, at least one of the end portion of the first lens region adjacent to the second lens region, the end portion of the second lens region adjacent to the third lens region, the end portion of the third lens region adjacent to the fourth lens region, and the end portion of the fourth lens region adjacent to the first lens region, is formed as the extended area which extends into the adjacent lens region by the predetermined angle. Therefore, the following effects can be obtained.
That is, when at least one of the end portions of the first to fourth lens regions is formed as the extended area which extends into the adjacent lens region by the predetermined angle, the reflective Fresnel lens on the rear surface of this extended area is formed on the basis of the reference line that is different from the reference line of their own region (i.e., on the basis of the reference line for forming the reflective Fresnel lens of the rear surface of the lens region into which the extended area extends). Therefore, a light distribution pattern which is formed by the light exiting from this extended area becomes a light distribution pattern that protrudes upward from the horizontal cutoff line and is given, at the upper end portion, an oblique cutoff line that extends obliquely upward toward the own vehicle lane side.
Therefore, a low beam light distribution pattern having horizontal and oblique cutoff lines can be formed by combining the light distribution pattern formed by the light exiting from the at least one extended area and the light distribution pattern formed by the light exiting from the remaining general areas. Furthermore, unlike in the conventional case, this is realized without blocking a portion of direct light from the light emitting surface with a shade.
A light low-beam distribution pattern for the left-hand traffic can be formed by arranging the first to fourth lens regions counter clockwise around the optical axis. On the other hand, a low beam light distribution pattern for the right-hand traffic can be formed by arranging the first to fourth lens regions clockwise around the optical axis.
As described above, in a direct projector type vehicle lamp using a rectangular light emitting surface as a light source, the invention makes it possible to form a low beam light distribution pattern having horizontal and oblique cutoff lines along the upper end portion while improving efficiency of utilizing light flux from the light source.
In the above configuration, when a portion of the lens near the optical axis is configured as a convex lens portion to project light emitted from the point on the bottom edge of the light emitting surface and on the optical axis as light parallel to the optical axis at least with respect to an up-down direction, a light distribution pattern having a horizontal cutoff line along its upper end portion can be formed as an inverted projection image of the light emitting surface formed by the convex lens portion. The horizontal cutoff line of this light distribution pattern and the horizontal cutoff line of the horizontally diffused light distribution pattern can substantially be aligned at the same position in the up-down direction. Therefore, by combining this light distribution pattern with the light distribution patterns formed by light exiting from the first to fourth lens regions, the low beam light distribution pattern can be given a clearer horizontal cutoff line.
In the above configuration, when a front surface of a section of the general area of each of the lens regions on a side of an end opposite to said end portion is configured to downwardly deflect the light exiting from said section, the following effect can be obtained.
That is, an upper end of a light distribution pattern to be formed by light exiting from the section of the general area of each of the lens regions on the side of the end opposite to the aforesaid end portion is slightly deviated upward than those formed by light exiting from the other sections. Therefore, by downwardly deflecting the light exiting from this section, the horizontal cutoff line of the low beam light distribution pattern can be made even clearer.
As mentioned above, the angular range (the predetermined angles) in which the respective extended areas are formed is not particularly limited. However, when each of the extended area is formed in an angular range of 5° to 12° with respect to a vertical line or a horizontal line that passes through the reference line (the first reference line or the second reference line) of the lens region to which the extended area belongs, the oblique cutoff line of the light distribution pattern formed by the extended area can be made a clear oblique cutoff line that is inclined upward by about 15° toward the own vehicle lane side.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of a vehicle lamp 10 according to an embodiment of the present invention;
Fig. 2 is an enlarged sectional view, illustrating a portion of a sectional view taken along the line II-II of Fig. 1 in an enlarged manner;
Fig. 3 is a perspective view of a lens 14 of the vehicle lamp 10 alone;
Fig. 4 is a front view for illustrating a positional relationship of rear surfaces of first to fourth lens regions of the lens 14 and a light emitting surface;
Fig. 5 is a diagram illustrating, in a seethrough manner, a low beam light distribution patterns to be formed on a virtual vertical screen located 25m ahead of the lamp by forwardly projected light from the vehicle lamp 10;
Fig. 6 illustrates (a): a diagram showing a simulation result of the low beam light distribution pattern, and (b), (c) and (d): diagrams showing the simulation results of three light distribution patterns constituting the low beam light distribution pattern.
Fig. 7 shows results of a simulation that was performed to explain how two of the three light distribution patterns are formed; and
Fig. 8 shows results of a simulation that was performed to explain how one of the two light distribution patterns is formed.

EMBODIMENTS OF THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a front view of a vehicle lamp 10 according to the embodiment. Fig. 2 is a detailed sectional view taken along the line II-II of Fig. 1.
As shown in these drawings the vehicle lamp 10 according to the embodiment includes a light emitting device 12 disposed to face forward adjacent to an optical axis Ax extending in the front-rear direction of the lamp, a lens 14 disposed in front of the light emitting device 12 to deflect and to forwardly project light from the light emitting device 12, and a metal holder 16 supporting the light emitting device 12 and the lens 14.
The vehicle lamp 10 is used in a condition that it is incorporated such that the optical axis is adjustable with respect to a lamp body or the like (not shown). With the optical axis adjustment being completed, the optical axis Ax extends in a direction of about 0.5° to 0.6° downward with respect to the front direction of the vehicle. A low beam light distribution pattern PL as shown in Fig. 5 for left-hand traffic is formed by light irradiation by the vehicle lamp 10.
The light emitting device, which is white light emitting diodes, is composed of four light emitting chips 12a arranged in series in the horizontal direction and a substrate 12b which supports the light emitting chips 12a.
The front surfaces of the four light emitting chips 12a are sealed by a thin film in a state that they are arranged substantially in close contact with each other, thereby forming a light emitting surface 12A which emits light in a laterally long rectangular shape when observed from the front of the lamp. Each of the light emitting chips 12a has a external form of about 1mm × 1mm square, and hence the light emitting surface 12A has an external form of about 1mm × 4mm.
The light emitting device 12 is disposed such that the bottom edge of the light emitting surface 12A extends along a horizontal line that intersects the optical axis Ax perpendicularly and point O (more specifically, the middle point in the right-left direction) on the bottom edge is placed on the optical axis Ax.
Fig. 3 is a perspective view of the lens 14 alone.
As shown in this drawing, the lens 14 is a disc-shaped member having an outer diameter of about 80mm and made of a colorless, transparent acrylic resin. The front surface and the rear surface of the lens 14 are both roughened.
A portion of the lens 14 near the optical axis Ax is configured as a convex lens portion Z0, and a portions surrounding the convex lens portion Z0 are configured as first to fourth lens regions Z1-Z4 having a reflective Fresnel lens structure. The first lens region Z1 is disposed primarily as an upper portion on the own vehicle lane side. The second lens region Z2 is disposed primarily as an upper portion on the opposing traffic lane side. The third lens region Z3 is disposed primarily as a lower portion on the opposing traffic lane side. The fourth lens region Z4 is disposed primarily as a lower portion on the own vehicle lane side.
As shown in Fig. 2, the convex lens portion Z0 is a plano-convex lens whose rear surface is a flat surface that is perpendicular to the optical axis Ax and whose rear focal point is located at point O (located on the optical axis Ax) of the bottom edge of the light emitting surface 12A. As a result, the convex lens portion Z0 causes light emitted from point O (located on the optical axis Ax) of the bottom edge of the light emitting surface 12A to travel forward along an optical path indicated by thick solid lines in Fig. 2 as light that is parallel to the optical axis Ax.
Next, the structures of the first to fourth lens regions Z1-Z4 will be described.
First, the shapes of the rear surfaces of the first to fourth lens regions Z1-Z4 will be described.
Fig. 4 is a front view for illustrating a positional relationship of the rear surfaces of the first to fourth lens regions Z1-Z4 and the light emitting surface 12A.
As shown in Fig. 4, the rear surfaces of the first and third lens regions Z1 Z3 are formed with a plurality of annular zonal prisms 14p1 in a concentric manner around a first reference line L1 as the center. The annular zonal prisms 14pl have a serrated cross section along a plane including the first reference line L1 which passes through a first corner point A at the top corner of the light emitting surface 12A on the side of the own vehicle lane (the top right corner when observed from the front of the lamp) and which extends parallel to the optical axis Ax.
The annular zonal prisms 14p1 are configured as a reflective Fresnel lens such that each of the annular zonal prisms 14p1 refracts light from the first corner point A by an inner circumferential surface of the annular zonal prisms 14p1 in a direction away from the first reference line L1 to cause the light to enter the annular zonal prism 14p1 and such that the entered light is totally reflected toward the front by an outer circumferential surface of the annular zonal prisms 14p1 (see Fig. 2).
On the other hand, the rear surfaces of the second and fourth lens regions Z2, Z4 are formed with a plurality of annular zonal prisms 14p2 in a concentric manner around a second reference line L2 as the center. The annular zonal prisms 14p2 have a serrated cross section along a plane including the second reference line L2 which passes through a second corner point B at the bottom corner of the light emitting surface 12A on the side of the opposing traffic lane (the bottom left corner when observed from the front of the lamp) and which extends parallel to the optical axis Ax.
The annular zonal prisms 14p2 are configured as a reflective Fresnel lens such that each of the annular zonal prisms 14p2 refracts light emitted from the second corner point B by an inner circumferential surface of the annular zonal prism 14p2 in a direction away from the second reference line L2 to cause the light to enter the annular zonal prism 14p2 and such that the entered light is totally reflected toward the front by an outer circumferential surface of the annular zonal prism 14p2.
From the viewpoint of forming a horizontally diffused light distribution pattern having a horizontal cutoff line along its upper end portion (described later), the first to fourth lens regions Z1-Z4 are supposed to be sectioned from each other by the horizontal line and the vertical line (indicated by two-dot chain lines in the drawing) that passes through a third corner point C at the bottom corner of the light emitting surface 12A on the side of the own vehicle lane (the bottom-right corner when observed from the front of the lamp). However, in the embodiment, an end portion, adjacent to the second lens region. Z2, of the first lens region Z1, an end portion, adjacent to the third lens region Z3, of the second lens region Z2, an end portion, adjacent to the fourth lens region Z4, of the third lens region Z3, and an end portion, adjacent to the first lens region Z1, of the fourth lens region Z4 are formed as fan-shaped extended areas Z1 a, Z2a, Z3a, Z4a which extend into the adjacent lens regions Z1, Z2, Z3, and Z4 by predetermined angles, respectively.
The extended area Z1a of the first lens region Z1 and the extended area Z3a of the third lens region Z3 are formed in an angular range of angles α1, α3 from the vertical line passing through the first corner point A (i.e., the vertical line passing through the first reference line L1), respectively. Each of the angles α1, α3 is set at about 10° to 12° (e.g., 11°). On the other hand, the extended area Z2a of the second lens region Z2 and the extended area Z4a of the fourth lens region Z4 occupy angular ranges of angles α2, α4 as measured from the horizontal line passing through the second corner point B (i.e., the horizontal line passing through the second reference line L2), respectively. Each of the angles α2, α4 is set at about 7° to 8° (e.g., 7.5°).
As a result, the first lens region Z1 is formed in a range of an angle θ] which is expanded from its original range by the angle α1 of the extended area Z1a and the remaining general area Z1o is reduced by the angle α4 of the extended area Z4a. The second lens region Z2 is formed in a range of an angle θ2 which is expanded from its original range by the angle α2 of the extended area Z2a and the remaining general area Z20 is reduced by the angle α1 of the extended area Z1a. The third lens region Z3 is formed in a range of an angle θ3 which is expanded from its original range by the angle α3 of the extended area Z3a and the remaining general area Z3o is reduced by the angle α2 of the extended area Z2a. The fourth lens region Z4 is formed in a range of an angle θ4 which is expanded from its original range by the angle α4 of the extended area Z4a and the remaining general area Z4o is reduced by the angle α3 of the extended area Z3a.
Next, the shapes of the front surfaces of the first to fourth lens regions Z1-Z4 will be described.
As shown in Figs. 1-3, the front surfaces of the extended areas Z1a-Z4a of the first to fourth lens regions Z1-Z4 are flat surfaces which are perpendicular to the optical axis Ax. And the front surface of each of the other, general areas Z1o-Z4o is formed with a plurality of horizontally diffusing elements 14s1 and 14s2 which outputs light that is diffused in the horizontal direction.
Each of the general areas Z1o-Z4o of the first to fourth lens regions Z1-Z4 is divided into three fan-shaped sections in the circumferential direction.
Each of central fan-shaped sections Z1o1-Z4o1 of the respective general areas Z1o-Z4o is configured such that a surface that is perpendicular to the optical axis Ax is formed with a plurality of horizontally diffusing elements 14s1. Each horizontally diffusing element 14s1 has a convex circular arc shape in horizontal cross section. Configured in this manner, each of the fan-shaped sections Z1o1-Z4o1 outputs light while diffusing it approximately equally to the right side and the left side.
Each of fan-shaped sections Z1o2-Z4o2, adjacent to the respective extended areas Z1a-Z4a, of the respective general areas Z1o-Z4o is configured such that a surface that is perpendicular to the optical axis Ax is formed with a plurality of horizontally diffusing elements 14s2. Each horizontally diffusing element 14s2 has, in horizontal cross section, a convex circular arc shape which is smaller in curvature than each horizontally diffusing element 14sl. Configured in this manner, each of the fan-shaped sections Z1o2-Z4o2 outputs light while diffusing it at relatively small diffusion angles approximately equally to the right side and the left side.
Each of fan-shaped sections Z1o3-Z4o3_, opposite to the respective extended areas Z1a-Z4a, of the respective general areas Z1o-Z4o is configured such that a surface that is a little inclined rearward (i.e., its top edge is deviated rearward) from a surface that is perpendicular to the optical axis Ax is formed with a plurality of horizontally diffusing elements 14sl. Each horizontally diffusing element 14s2 has, in horizontal cross section, a convex circular arc shape which is smaller in curvature than each horizontally diffusing element 14s1. Configured in this manner, each of the fan-shaped sections Z1o3-Z4o3 outputs light a tittle downward while diffusing it approximately equally to the right side and the left side.
Fig. 5 is a diagram illustrating, in a seethrough manner, a low beam light distribution pattern PL formed on a virtual vertical screen located 25m ahead of the lamp by forwardly projected light from the vehicle lamp 10.
This low beam light distribution pattern PL, which is a low beam light distribution pattern for a left-hand traffic, has a horizontal cutoff line CL1 and an oblique cutoff line CL2 along its upper end portion. The horizontal cutoff line CL1 extends to the opposing traffic lane side of a vertical line V-V which passes through the vanishing point H-V in the front direction of the lamp. The oblique cutoff line CL2 having an inclination angle 15° is formed on the own vehicle lane side. An elbow point E which is the intersection of the two cutoff lines CL I, CL2 is deviated downward from the point H-V by about 0.5° to 0.6°.
The low beam light distribution pattern PL is a composite light distribution pattern obtained by superimposing three light distribution patterns PA, PB, PC on each other.
The light distribution pattern PA is a light distribution pattern that is formed by light emitted from the convex lens portion Z0. The light distribution pattern PB is a light distribution pattern that is formed by light exiting from the general areas Z1o-Z4o of the first to fourth lens regions Z1-Z4. The light distribution pattern PC is a light distribution pattern that is formed by light exiting from the extended areas Z1a-Z4a of the first to fourth lens regions Z1-Z4.
The light distribution pattern PA is a bright, oblong light distribution pattern which extends narrowly from the line V-V to both of the right side and the left side. The top edge of the light distribution pattern PA forms a main portion of the horizontal cutoff line CL1. The light distribution pattern PA is formed by projecting an inverted image of the light emitting surface 12A by the convex lens portion Z0. Since the bottom edge of the light emitting surface 12A is located on the horizontal line that passes through the rear focal point of the convex lens portion Z0, the light-dark ratio of the top edge of the light distribution pattern PA is extremely large and hence the main portion of the horizontal cutoff line CL1 is clear. The top edge of the light distribution pattern PA is deviated downward from the point FH-V by about 0.5° to 0.6° because the optical axis Ax of the vehicle lamp 10 extends downward with respect to the vehicle front direction by about 0.5° to 0.6°.
The light distribution pattern PB is an oblong light distribution pattern which extends widely from the line V-V to both of the right side and the left side. The top edge of the light distribution pattern PB also contributes to the formation of the horizontal cutoff line CL1. How the light distribution pattern PB is formed will be described later.
The light distribution pattern PC is a bright, obliquely oblong light distribution pattern which narrowly extends obliquely upward from the vicinity of the line V-V to the own vehicle lane side. The top edge of the light distribution pattern PC forms the oblique cutoff line CL2. How the light distribution pattern PC is formed will also be described later.
In the low beam light distribution pattern PL, a hot zone HZ is a high luminosity region which is formed at a position that is on the bottom-left of the elbow point E and in which the light distribution pattern PB and the light distribution pattern PC are superimposed on each other.
Fig. 6(a) is a diagram showing a simulation result of the low beam light distribution pattern PL. Figs. 6(b), 6(c) and 6(d) are diagrams showing the simulation results of the light distribution pattern PC, the light distribution pattern PA, and the light distribution pattern PB, respectively.
In each of these figures, multiple closed curves are equi-intensity curves of light. It is seen that in each of the light distribution patterns PL, PC, PA, PB the luminosity increases as the position goes away from the periphery, that is, comes closer to the center.
Whereas the light distribution pattern PA is brightest at the center and its vicinity, each of the light distribution patterns PB, PC is brightest at a position that is deviated from the center toward the elbow point E.
Figs. 7 and 8 show results of simulations that were performed to explain how the light distribution patterns PB, PC are formed.
First, a description will be made with regard to Fig. 7.
Fig. 7(b) shows, together with the light distribution pattern PA which is formed by light emitted from the convex lens portion Z0 (see Fig. 7(a)), eight light distribution patterns P1o-P4o and P1a-P4a that would be formed by light exiting from the general areas Z1o-Z4o and the extension potions Zla-Z4a, respectively, if the front surfaces of the first to fourth lens regions Z 1-Z4 of the lens 14 were a flat surface that is perpendicular to the optical axis Ax (see Fig. 7(a)).
Each of the light distribution patterns P1o-P40 which are formed by light exiting from the general areas Z1o-Z4o is almost entirely formed under the horizontal cutoff line CL1. This is because the general areas Z1o, Z3o are formed on the basis of the first reference line L1 and the general areas Z2o, Z4o are formed on the basis of the second reference line L2.
On the other hand, a portion of each of the light distribution patterns Pla-P4a which are formed by light exiting from the extension potions Z1a-Z4a projects upward from the horizontal cutoff line CL1. This is because the extension potions Z1a, Z3a are formed with the second reference line L2 as a reference rather than the first reference line L1 and the extension potions Z2a, Z4a are formed with the first reference line L1 as a reference rather than the second reference line L2.
The light distribution patterns Pla-P4a are formed such that their top edges extend along the oblique cutoff line CL2. This is because the extension potions Z1a, Z3a are within the angular ranges of the angles α1; α3, respectively, and the extension potions Z2a, Z4a are within the angular ranges of the angles α2, α4, respectively.
The top edges of the light distribution patterns P1a, P3a which are formed by light exiting from the extension potions Z1a, Z3a are formed by the top edge of the light emitting surface 12A, and the end point of each top edge on the side of the elbow point E is formed by the first corner point A of the light emitting surface 12A. On the other hand, the top edges of the light distribution patterns P2a and P4a which are formed by light exiting from the extension potions Z2a, Z4a are formed by the bottom edge of the light emitting surface 12A, and the end point of each top edge on the side of the elbow point E is formed by the second corner point B of the light emitting surface 12A.
The light distribution pattern PC shown in Fig. 6(b) is formed as a composite light distribution pattern obtained by superimposing the above four light distribution patterns Pla-P4a on each other.
Next, a description will be made with regard to Fig. 8.
As described above in connection with Fig. 3, the general areas Z1o-Z4o of the first to fourth lens regions Z1-Z4 are divided into the three kinds of fan-shaped sections Z1o1-Z4o1, Z1o2-Z4o2, and Z1o3-Z4o3, and the fan-shaped sections Zlo3-Z4o3 of the one kind are configured to output light beams while deflecting them a little downward. Therefore, consideration will be given such that the general areas Z1o-Z4o are divided into two kinds of fan-shaped sections Z1o1-Z4o1 and Z1o2-Z4o2 and the remaining one kind of fan-shaped sections Z1o3-Z4o3 (see Fig. 8(a)).
As shown in Fig. 8(b), light distribution patterns P1oA-P4oA which are formed by light exiting from the two kinds of fan-shaped sections Z1o1-Z4o1 and Z1o2-Z4o2 of the general areas Z1o-Z4o become parts of the light distribution patterns P1o-P4o shown in Fig. 7(b) as they are. On the other hand, as shown in Fig. 8(b), light distribution patterns P1oB-P4oB which are formed by light exiting from the remaining one kind of fan-shaped sections Z1o3-Z4o3 become light distribution patterns as obtained by shifting the remaining parts of the light distribution patterns P1o-P4o shown in Fig. 7(b) a little downward. The top edges of the light distribution patterns P1oB-P4oB without such downward shifting are indicated by broken lines in Fig. 8(b).
As a result, in the light distribution patterns P1o-P4o shown in Fig. 7(b), the top edges of those small parts of the light distribution patterns P1oB-P4oB which are located above the horizontal cutoff line CL1 are located substantially on the horizontal cutoff line CL1 like the top edges of the light distribution patterns P1oA-P4oA. Eight light distribution patterns are formed by diffusing each of the light distribution patterns P1oA-P4oA and the P1oB-P4oB to both of the right side and the left side by means of the plurality of horizontally diffusing elements 14S1 and 14s2, and the light distribution pattern PB shown in Fig. 6(d) is formed as a composite light distribution pattern obtained by superimposing these eight light distribution patterns on each other.
The light distribution patterns P1oA-P4oA shown in Fig. 8(b) are horizontally diffused light distribution patterns that are low in light distribution unevenness because they are composite light distribution patterns obtained by superimposing, on each other, horizontally diffused light distribution patterns that are formed by light beams having relatively large diffusion angles emitted from the fan-shaped sections Z1o1-Z4o1 in each of which the plurality of horizontally diffusing elements 14s1 are formed and horizontally diffused light distribution patterns that are formed by light beams having relatively small diffusion angles emitted from the fan-shaped sections Z1o2-Z4o2 in each of which the plurality of horizontally diffusing elements 14s2 are formed. In addition, the horizontally diffused light distribution patterns that are formed by light exiting from the fan-shaped sections Z1o2-Z4o2 which are adjacent to the extended areas Z1a-Z4a in the general areas Z1o-Z4o, respectively, are formed on the basis of oblong light source images, and hence are made relatively bright light distribution patterns whose top edges extend along the horizontal cutoff line CL1 by setting the diffusion angles of those light beams relatively small.
As described above in detail, the vehicle lamp 10 according to the embodiment is configure such that light emitted from the light emitting surface 12A of the light emitting device 12 which is disposed in the vicinity of the optical axis Ax which extends in the front-rear direction of the lamp is output forward being deflected by the lens 14 which is disposed in front of the light emitting surface 12A. Since the rear surface of the lens 14 is formed with the reflective Fresnel lenses, the lamp can be made compact.
Furthermore, in the vehicle lamp 10 according to the embodiment, the light source has the light emitting surface 12A to rectangularly emit light when observed from the front of lamp and is disposed such that its bottom edge extends along a horizontal line that intersects the optical axis Ax perpendicularly and the point O on the bottom edge is placed on the optical axis Ax. The lens 14 has, with respect to the optical axis Ax, the first lens region Z1 disposed primarily as an upper portion on the own vehicle lane side, the second lens region Z2 disposed primarily as an upper portion on the opposing traffic lane side, the third lens region Z3 disposed primarily as a lower portion on the opposing traffic lane side, and the fourth lens region Z4 disposed primarily as a lower portion on the own vehicle lane side. The rear surfaces of the first and third lens regions Z1, Z3 and the rear surfaces of the second and fourth lens regions Z2, Z4 are formed with the reflective Fresnel lenses on the basis of the different reference lines respectively. Therefore, the following effects can be obtained.
More specifically, the rear surfaces of the first and third lens regions Z1, Z3 are formed with the plurality of annular zonal prisms 14pl that are concentric with the first reference line L1 as the center. The annular zonal prisms 14p1 have a serrated cross section along a plane including the first reference line L1 which passes through the first corner point A at the top corner of the light emitting surface 12A on the side of the own vehicle lane and which extends parallel to the optical axis Ax. The annular zonal prisms 14pl are configured as a reflective Fresnel lens such that each of the annular zonal prisms 14pl refracts light emitted from the first corner point A by the inner circumferential surface of the annular zonal prism 14pl in a direction away from the first reference line L1 cause the light to enter the annular zonal prism 14pl and such that the entered light is totally reflected toward the front by the outer circumferential surface of the annular zonal prism 14pl. Therefore, light exiting from the first and third lens regions Z1. Z3 are diffused in the horizontal direction by the plurality of horizontally diffusing elements 14sl and 14s2 which are formed in the front surfaces of their general areas Z1o, Z3o. whereby a horizontally diffused light distribution pattern having a horizontal cutoff line along the upper end portion can be formed so as to have approximately the same shape as a light distribution pattern PB and is approximately a half of the light distribution pattern PB in brightness.
On the other hand, the rear surfaces of the second and fourth lens regions Z2, Z4 are formed with the plurality of annular zonal prisms 14p2 that are concentric around the second reference line L2 as the center. The annular zonal prisms 14p2 have a serrated cross section along a plane including the second reference line L2 which passes through the second corner point B at the bottom corner of the light emitting surface 12A on the side of the opposing traffic lane and which extends parallel to the optical axis Ax. The annular zonal prisms 14p2 are configured as a reflective Fresnel lens such that each of the annular zonal prisms 14p2 refracts light emitted from the second corner point B by the inner circumferential surface of the annular zonal prism 14p2 in a direction away from the second reference line L2 to cause the light to enter the annular zonal prism 14p2 and such that the entered light is totally reflected toward the front by the outer circumferential surface of the annular zonal prism 14p2. Therefore, light exiting from the second and fourth lens regions Z2, Z4 are diffused in the horizontal direction by the plurality of horizontally diffusing elements 14sl and 14s2 which are formed in the front surfaces of their general areas Z2o and Z2o, whereby a horizontally diffused light distribution pattern having a horizontal cutoff line along the upper end portion can be formed so as to have approximately the same shape as the light distribution pattern PB and is approximately a half of the light distribution pattern PB in brightness.
The reflective Fresnel lens of the rear surfaces of the first and third lens regions Z1 Z3 is formed on the basis of the first reference line L1, and the reflective Fresnel lens of the rear surfaces of the second and fourth lens regions Z2, Z4 is formed on the basis of the second reference line L2. Therefore, both of the horizontal cutoff line of the horizontally diffused light distribution pattern formed by light exiting from the first and third lens regions Z1, Z3 and the horizontal cutoff line of the horizontally diffused light distribution pattern formed by light exiting from the second and fourth lens regions Z2, Z4 can be located at approximately the same position as the horizontal cutoff line CL 1.
In addition, in the vehicle lamp 10 according to the embodiment, the end portion, adjacent to the second lens region Z2, of the first lens region Z1, the end portion, adjacent to the third lens region Z3, of the second lens region Z2, the end portion, adjacent to the fourth lens region Z4, of the third lens region Z3, and the end portion, adjacent to the first lens region Z1, of the fourth lens region Z4 are formed as the extended areas Z1a, Z2a, Z3a, Z4a which extend into the adjacent lens regions Z2, Z3, Z4, Z1 by the predetermined angles, respectively. Therefore, the following effects can be obtained.
Where the end portions of the lens regions Z1, Z2, Z3, Z4 are formed as the extended areas Z1a, Z2a, Z3a, Z4a which extend into the adjacent lens regions Z2, Z3, Z4, Z1 by the predetermined angles, respectively, the reflective Fresnel lens on the rear surfaces of the extended areas Z1a, Z3a is formed on the basis of the second reference line L2 which is different from the first reference line L1 of their regions (the reference line for forming the reflective Fresnel lens of the rear surfaces of the lens regions Z2, Z4 into which the extended areas Z1a, Z3a extend), and the reflective Fresnel lens of the rear surfaces of the extended areas Z2a, Z4a is formed on the basis of the first reference line L1 which is different from the second reference line L2 of their own region (the reference line for forming the reflective Fresnel lens of the rear surfaces of the lens regions Z3, Z1 into which the extended areas Z2a, Z4a extends).
Therefore, light distribution patterns Pla-P4a which are formed by light exiting from the respective extended areas Z1a-Z4a become light distribution patterns that project upward from the horizontal cutoff line CL1 and are given, along the upper end portion, oblique cutoff lines CL2 that extend obliquely upward toward the own vehicle lane side.
Therefore, a low beam light distribution pattern PL having horizontal and oblique cutoff lines CL1, CL2 can be formed by combining a light distribution pattern PC which is a composite light distribution pattern of the four light distribution patterns Pla-P4a which are formed by light exiting from the four extended areas Z1a-Z4a and a light distribution pattern PB which is a composite light distribution pattern of four horizontally diffused light distribution patterns which are formed by light exiting from the four remaining, general areas Z1o-Z4o. Furthermore, unlike in the conventional case, the low beam light distribution pattern PL can be realized without blocking a portion of direct light from the light emitting surface 12A with a shade.
As described above, in the direct projector type vehicle lamp 10 using the rectangular light emitting surface 12A as the light source, the embodiment can form a low beam light distribution pattern having horizontal and oblique cutoff lines CL1, CL2 along its upper end portion while improving efficiency of utilizing light flux from the light source.
Furthermore, in the embodiment, the portion in the vicinity of the optical axis Ax is the convex lens portion Z0 which allows light emitted from point O which is located on the bottom edge of the light emitting surface 12A and the optical axis Ax to travel parallel to the optical axis Ax. Therefore, a light distribution pattern PA having a clear horizontal cutoff line along the upper end portion can be formed as an inverted projection image of the light emitting surface 12A formed by the convex lens portion Z0. By combining this light distribution pattern PA with the light distribution patterns PB, PC which are formed by light exiting from the first to fourth lens regions Z1-Z4, the low beam light distribution pattern PL can be given a clearer main portion of the horizontal cutoff line CL 1 and a brighter hot zone HZ.
In the embodiment, the front surfaces of the end fan-shaped sections Z1o3-Z4o3, opposite to the extended areas Zla-Z4a, of the general areas Z1o-Z4o of the lens regions Z1-Z4 are formed so as to output light beams while deflecting them downward, respectively. This provides the following effect.
If the front surfaces of the lens regions Z1-Z4 were a flat surface that is perpendicular to the optical axis Ax, the top ends of light distribution patterns P1oB-P4oB which are formed by light exiting from the fan-shaped sections Z1o3-Z4o3 of the general areas Z1o-Z4o of the lens regions Z1-Z4 would be a little deviated upward from those of light distribution patterns P1o1-P4o1 and P1o2-P4o2 which are formed by light exiting from the other fan-shaped sections Z1o1-Z4o1 and Z1o2-Z4o2. Therefore, the horizontal cutoff line CL1 of the low beam light distribution pattern PL can be made even clearer by deflecting, downward, light exiting from the fan-slipped sections Z1o3-Z4o3.
Furthermore, in the embodiment, the extended areas Z1a, Z3a of the first and third lens region Z1, Z3 are formed in the angular range of 10° to 12° with respect to the vertical line passing through the first reference line L1 and the extended areas Z2a, Z4a of the second and fourth lens region Z2, Z4 are formed in the angular range of 7° to 8° with respect to the horizontal line passing through the second reference line L2. Therefore, the top edges of light distribution patterns P1a-P4a which are formed by light exiting from the extended areas Z1a-Z4a can be made an oblique cutoff line that is inclined by about 15° and extends toward the own vehicle lane side, whereby the oblique cutoff line CL2 can be made clear.
Although the external form of the light emitting device 12 of the vehicle lamp 10 according to the embodiment has a rectangular shape of about I mm x 4 mm, an external form of the light emitting device to be used in the vehicle lamp 10 is not limited to this.
Although in the embodiment the front surfaces of the extended areas Z1a-Z4a of the first to fourth lens regions Z1-Z4 are flat surfaces that are perpendicular to the optical axis Ax, they may be formed with plural diffusion/deflection elements which diffuse or deflect, obliquely in the direction of the oblique cutoff line CL2, light exiting from the extended areas Z1a-Z4a.
Although in the embodiment the extended areas Zla-Z4a are formed in the first to fourth lends regions Z1-Z4, respectively, only arbitrary one, two, or three of the four extended areas Z1a-Z4a may be formed.
Although in the embodiment the convex lens portion Z0 is a general plano-convex lens, the cross section, taken along the horizontal plane, of the convex lens portion Z0 may be changed in a suitable manner so that the convex lens portion Z0 outputs light in a horizontally diffusing manner.
Although in the embodiment the middle point O, in the right-left direction, of the bottom edge of the light emitting surface 12A is located on the optical axis Ax, a point of the light emitting surface 12A other than the middle point O, in the right-left direction, of its bottom edge may be located on the optical axis Ax.
Although in the embodiment the front surfaces of the fan-shaped sections Z1o3-Z4o3 of the general areas Z1o-Z4 of the lens regions Z1-24 are formed so as to output light beams while diffusing them in the horizontal direction and deflecting them downward, the front surfaces of the fan-shaped sections Z1o3-Z4o3 may be such as to output light beams while diffusing them in the horizontal direction without deflecting them downward.
Although in the embodiment the portion, in the vicinity of the optical axis Ax, of the lens 14 is the convex lens portion Z0, the first to fourth lens regions Z1-Z4 may be extended to the vicinity of the optical axis Ax.
In the embodiment, the low beam light distribution pattern PL for the lefthand traffic is formed by light irradiation by the vehicle lamp 10. A low beam light distribution pattern for right-hand traffic can be formed by arranging the first to fourth lens regions Z1-Z4 clockwise around the optical axis Ax instead of arranging the first to fourth lens regions Z1-Z4 counterclockwise as in the embodiment.
The particular numerical values described in the embodiment are merely examples, and they can of course be set to different numerical values where appropriate.
This application is based on Japanese Patent Application No. 2008-296967 filed on November 20, 2008 , the content of which is incorporated herein by reference.

EXPLANATION OF PREFERENCE SIGNS

10:: Vehicle Lamp
12:: Light Emitting Device
12A:: Light Emitting Surface
12a:: Light Emitting Chip
12b:: Substrate
14:: Lens
14p1, 14p2:: Annular Zonal Prisms
1.4s1, 14s2:: Horizontally Diffusing Elements
16:: Holder
A:: First Corner Point
Ax:: Optical Axis
B:: Second Corner Point
C:: Third Corner Point
CL1:: Horizontal Cutoff Line
CL2:: Oblique Cutoff Line
E:: Elbow Point
HZ:: Hot Zone
L1:: First Reference Line
L2:: Second Reference Line
C):: Point on Bottom Edge of Light Emitting Surface and on Optical Axis
PA, PB, PC:: Light Distribution Patterns
PL:: Low Beam Light Distribution Pattern
P1a, P1o, P1oA, P1oB, P2a, P2o, P2oA
, P2oB, P3a, P3o, P3oA. P3oB, P4a,
P4o, P4oA, P4oB:: Light Distribution Patterns
Z0:: Convex Lens portion
Z1 :: First Lens Region
Z1a, Z2a, Z3a, Z4a:: Extended Area
Z1o, Z2o, Z3o, Z4o:: General Area
Z1o1, Z1o2, Z1o3, Z2o1, Z2o2, Z2o3,
Z3o1, Z3o2, Z3o3, Z4o1, Z4o2, Z4o3:: Fan-Shaped Section
Z2:: Second Lens Region
Z3:: Third Lens Region
Z4:: Fourth Lens Region
α1 α2, α3, α4, θ1, θ2, θ3, θ4:: Angles

Claims

A vehicle lamp comprising a light source disposed adjacent to an optical axis extending in a front-rear direction of the lamp, and a lens disposed in front of the light source to deflect and to forwardly project light from the light source,
characterized in that:
the light source has a light emitting surface to rectangularly emit light when observed from a front of the lamp, and disposed such that a bottom edge of the light emitting surface extends along a horizontal line that is perpendicular to the optical axis and such that the optical axis intersects the bottom edge,

the lens comprises, around the optical axis, a first lens region disposed primarily as an upper portion on a side of the own vehicle lane, a second lens region disposed primarily as an upper portion on a side of the opposing traffic lane, a third lens region disposed primarily as a lower portion on the side of the opposing traffic lane, and a fourth lens region disposed primarily as a lower portion on the side of the own vehicle lane,

rear surfaces of the first and third lens regions are formed with a plurality of annular zonal prisms in a concentric manner around a first reference line as a center, the annular zonal prisms having a serrated cross section along a plane including the first reference line, wherein the first reference line passes through a first corner point at a top corner of the light emitting surface on the side of the own vehicle lane and extends parallel to the optical axis,

the annular zonal prisms are configured as a reflective Fresnel lens such that each of the annular zonal prisms refracts light emitted from the first corner point by an inner circumferential surface of the annular zonal prism in a direction away from the first reference line to cause the light to enter the annular zonal prism and such that the entered light is then totally reflected toward the front by an outer circumferential surface of the annular zonal prism,

rear surfaces of the second and fourth lens regions are forked with a plurality of annular zonal prisms in a concentric manner around a second reference line as a center, the annular zonal prisms having a serrated cross section along a plane including the second reference line, wherein the second reference line passes through a second corner point at a bottom corner of the light emitting surface on the side of the opposing traffic lane and extends parallel to the optical axis,

the angular zonal prisms are configured as a reflective Fresnel lens such that each of the annular zonal prisms refracts light emitted from the second corner point by an inner circumferential surface of the annular zonal prism in a direction away from the second reference line to cause the light to enter the annular zonal prism and such that the entered light is then totally reflected toward the front by an outer circumferential surface of the annular zonal prism,

at least one of an end portion of the first lens region adjacent to the second lens region, an end portion of the second lens region adjacent to the third lens region, an end portion of the third lens region adjacent to the fourth lens regions, and an end portion of the fourth lens region adjacent to the first lens region, is formed as a fan-shaped extended area extending into the adjacent lens region by a predetermined angle, and

a front surface of a general area of each of the first to fourth lens regions other than the extended area is formed with a plurality of horizontally diffusing elements to horizontally diffuse light exiting from the general area.
The vehicle lamp according to claim 1, characterized in that a portion of the lens near the optical axis is configured as a convex lens portion to project light emitted from the point on the bottom edge of the light emitting surface and on the optical axis as light parallel to the optical axis at least with respect to an up-down direction.
The vehicle lamp according to claim 1 or 2, characterized in that a front surface of a section of the general area of each of the lens regions on a side of an end opposite to said end portion is configured to downwardly deflect the light exiting from said section.
The vehicle lamp according to any one of claims 1 to 3, characterized in that each of the extended area is formed in an angular range of 5° to 12° with respect to a vertical line or a horizontal line that passes through the reference line of the lens region to which the extended area belongs.