Patent Publication Number: US-2019170316-A1

Title: Vehicle lighting fixture

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicular lamp. 
     BACKGROUND 
     Patent Literature 1 discloses a vehicular front light capable of controlling an adaptive driving beam that varies a driving-beam light distribution pattern, to suppress glare light emitted to a leading vehicle. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1; 
     Japanese Unexamined Patent Application Publication No. 2013-20709 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, recently, there has been a need for further enhancement in the controllability and functions of the driving-beam light distribution pattern. 
     An object of the present invention, which has been conceived in light of the above-described circumstances, is to provide a vehicular lamp having functionalities more enhanced than those of the related art. 
     Means for Solving the Problem 
     In order to achieve the above object, the present invention is realized by the following constitution. 
     (1) A vehicular lamp according to the present invention comprising: a light source unit; and a lens disposed in front of the light source unit, wherein, the light source unit comprises: a substrate; a first light-emitting chip array comprising a plurality of semiconductor-type first light-emitting chips disposed on the substrate and arrayed along a horizontal direction; a second light-emitting chip array comprising a plurality of semiconductor-type second light-emitting chips disposed on the substrate and arrayed along the horizontal direction; and a third light-emitting chip array comprising a plurality of semiconductor-type third light-emitting chips disposed on the substrate and arrayed along the horizontal direction, the second light-emitting chip array is disposed on the substrate at a first distance below the first light-emitting chip array in the vertical direction, the third light-emitting chip array is disposed on the substrate at a second distance below the second light-emitting chip array in the vertical direction, and the first distance is larger than the second distance. 
     (2) The vehicular lamp according to the (1), wherein, the second light-emitting chip array comprises the second light-emitting chips by a number smaller than or equal to the number of the first light-emitting chips of the first light-emitting chip array, and the third light-emitting chip array comprises the third light-emitting chips by a number smaller than or equal to the number of the second light-emitting chips of the second light-emitting chip array. 
     (3) The vehicular lamp according to the (1) or (2), wherein the number of the first light-emitting chips is the same as the number of the second light-emitting chips and the number of the third light-emitting chips. 
     (4) The vehicular lamp according to any the (1) to (3), wherein the first light-emitting chip array, the second light-emitting chip array, and the third light-emitting chip array emit light that forms a portion of a driving-beam light distribution pattern. 
     (5) The vehicular lamp according to any the (1) to (4), wherein, the light source unit comprises a fourth light-emitting chip array comprising a plurality of semiconductor-type fourth light-emitting chips disposed on the substrate and arrayed along the horizontal direction, the fourth light-emitting chip array is disposed on the substrate above and apart from the first light-emitting chip array in the vertical direction, and the number of the fourth light-emitting chips is smaller than the number of the first light-emitting chips. 
     (6) A vehicular lamp according to the present invention comprising: a light source unit; and a lens disposed in front of the light source unit, wherein, the light source unit comprises: a substrate; a first light-emitting chip array comprising a plurality of semiconductor-type first light-emitting chips disposed on the substrate and arrayed along a horizontal direction; and a fourth light-emitting chip array comprising a plurality of semiconductor-type fourth light-emitting chips disposed on the substrate and arrayed along the horizontal direction, the fourth light-emitting chip array is disposed on the substrate above and apart from the first light-emitting chip array in a vertical direction, and the number of the fourth light-emitting chips is smaller than the number of the first light-emitting chips. 
     (7) The vehicular lamp according to the (5) or (6), wherein, the fourth light-emitting chip array is a portion for forming a marking light distribution pattern, and a light distribution pattern formed by light from the fourth light-emitting chip array is radiated below a light distribution pattern formed by light from the first light-emitting chip array. 
     (8) The vehicular lamp according to any the (5) to (7), wherein the number of the fourth light-emitting chips disposed on an inner side of a vehicle with reference to a vertical line extending through a lamp optical axis is larger than the number of the fourth light-emitting chips disposed on an outer side of the vehicle. 
     (9) The vehicular lamp according to any the (5) to (8), wherein, the light source unit comprises at least one upper light-emitting chip array disposed on the substrate above and apart from the fourth light-emitting chip array in the vertical direction, the upper light-emitting chip array comprises an array of upper light-emitting chips disposed on the substrate in the horizontal direction, the array of the upper light-emitting chips being the same as the fourth light-emitting chips of the fourth light-emitting chip array, and the upper light-emitting chip array is a portion for forming a marking light distribution pattern to be radiated below incident light emitted from the fourth light-emitting chip array on a screen. 
     (10) The vehicular lamp according to the (9), wherein the fourth light-emitting chips of the fourth light-emitting chip array and the light-emitting chips of the upper light-emitting chip array are controlled to be turned on at different timings. 
     (11) The vehicular lamp according to any the (1) to (10), wherein the substrate comprises a multilayer wiring board comprising multiple layers having wiring patterns stacked in a thickness direction. 
     Effect of the Invention 
     According to the present invention, a vehicular lamp having functionalities more enhanced than those of the related art can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a vehicle including vehicular lamps according to a first embodiment of the present invention. 
         FIG. 2  is a perspective view of the main components of a lamp unit according to the first embodiment of the present invention. 
         FIG. 3  is a plan view of a light source unit according to the first embodiment of the present invention. 
         FIG. 4  illustrates light distribution patterns formed on a screen by light from each light-emitting chip array according to the first embodiment of the present invention, in which (a) illustrates a light distribution pattern on a screen when first light-emitting chips in a first light-emitting chip array are all turned on; (b) illustrates a light distribution pattern on a screen when second light-emitting chips in a second light-emitting chip array are all turned on; (c) illustrates a light distribution pattern on a screen when third light-emitting chips in a third light-emitting chip array are all turned on; and (d) illustrates a light distribution pattern on a screen when bottom light-emitting chips in a bottom light-emitting chip array are all turned on. 
         FIG. 5  illustrates a driving-beam light distribution pattern on a screen according to the first embodiment of the present invention. 
         FIG. 6  illustrates a case in which some of the light-emitting chips are turned off in response to a leading vehicle or an oncoming vehicle. 
         FIG. 7  illustrates the configuration of a second embodiment of the present invention. 
         FIG. 8  illustrates a marking light distribution pattern according to the second embodiment of the present invention. 
         FIG. 9  is a plan view of a light source unit according to the second embodiment of the present invention including an upper light-emitting chip array. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, modes for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described in detail with reference to the accompanying drawings. Like elements throughout the entire description of the embodiments will be denoted by like numerals. 
     Also, unless otherwise noted, in the embodiments and drawings, “front” and “rear” indicate a “forward direction” and a “reverse direction,” respectively, of the vehicle, and “upper,” “lower,” left,” and “right” all indicate directions from the viewpoint of a driver riding in the vehicle. 
     Vehicular lamps according to the embodiments of the present invention are vehicular front lights ( 101 R,  101 L) provided on the left and right sides, respectively, at the front of a vehicle  102  illustrated in  FIG. 1 , which will hereinafter simply be referred to as vehicular lamps. In the description below, the right and left vehicular lamps have the same configuration unless otherwise specified to have a configuration for the left vehicular lamp or the right vehicular lamp. 
     First Embodiment 
     A vehicular lamp according to the first embodiment includes a housing (not illustrated) open to the front of the vehicle and an outer lens (not illustrated) attached to the housing so as to cover the opening. A lamp unit  10  (see  FIG. 2 ) is disposed in a lamp chamber defined by the housing and the outer lens. 
       FIG. 2  is a perspective view illustrating the main components of the lamp unit  10 . As in the subsequent drawings, an X axis indicates the horizontal direction of the vehicle  102 , a Y axis indicates the vertical direction of the vehicle  102 , and a Z axis indicates a lamp optical axis of a lamp unit. 
     As illustrated in  FIG. 2 , the lamp unit  10  includes a light source unit  20  and a lens  21  disposed in front of the light source unit  20 . Note that the light source unit  20  is disposed on a heat sink, and the lens  21  is also attached to the heat sink via a lens holder. Thus, although  FIG. 2  illustrates only the lens  21 , which is the part that performs light distribution control, the vehicular lamp includes, for example, a lens member to be held by the lens holder, the lens member having flanges formed at the two ends thereof in the horizontal direction (the X axis direction) of the lens  21 . 
     Note that the positions at which the flanges are provided are not limited to the two ends in the horizontal direction (the X axis direction). The lens  21  may be attached to the lens holder through any method, such as fixing a circumferential end face of the lens  21  to the lens holder with an adhesive agent, the method not being particularly limited. 
     (Lens) 
     The lens  21  has a rectangular shape in front view and is composed of, for example, an acrylic resin, such as PMMA, transparent resin, such as polycarbonate (PC) or polycyclohexylenedimethylene terephthalate (PCT), or glass. Note that, from the viewpoint of processability, the lens  21  is desirably made of transparent resin. Among resins, acrylic resin having low wavelength dependency of the refractive index and capable of reducing the influence of spectroscopy is desirably used. 
     As described below, the light source unit  20  according to this embodiment includes many light-emitting chips. Thus, for example, when the distance between the lens  21  and the light source unit  20  is small, the temperature of the lens  21  may become high. When the temperature of the lens  21  becomes high in this way, it is preferred that the lens  21  be composed of a material having satisfactory heat resistance, such as polycarbonate (PC) or glass. 
     (Light Source Unit) 
       FIG. 3  is a plan view of the light source unit  20 . Note that  FIG. 3  is a plan view of the light source unit  20  from the rear side of the vehicle, indicating the external shape of a substrate  30  by dotted lines and mainly illustrating light-emitting chips disposed on the substrate  30 . 
     With reference to  FIG. 3 , the light source unit  20  includes a substrate  30 , a first light-emitting chip array  40  including many semiconductor-type first light-emitting chips  41  disposed along the horizontal direction (the X axis direction) on the substrate  30 , a second light-emitting chip array  50  including many semiconductor-type second light-emitting chips  51  disposed along the horizontal direction (the X axis direction) on the substrate  30 , and a third light-emitting chip array  60  including many semiconductor-type third light-emitting chips  61  disposed along the horizontal direction (the X axis direction) on the substrate  30 . 
     This embodiment further includes a bottom light-emitting chip array  70  including many semiconductor-type bottom light-emitting chips  71  disposed along a horizontal direction on the substrate  30 . 
     Note that, in this embodiment, the first light-emitting chips  41 , the second light-emitting chips  51 , the third light-emitting chips  61 , and the bottom light-emitting chips  71  are LED chips. Alternatively, they may be semiconductor-type light-emitting chips, such as LD chips. 
     (Substrate) 
     With reference to  FIG. 3 , many light-emitting chips are densely arranged on the substrate  30 . Thus, it is preferred that the substrate  30  be a multilayer wiring board, not a monolayer circuit board, including multiple layers having wiring patterns stacked in the thickness direction, so that many light-emitting chips can be densely arranged. 
     For example, a buildup board can be desirably used as the substrate  30 , the buildup board including multiple layers having wiring patterns stacked in the thickness direction by alternately forming circuits and substrates on a first substrate on which a first circuit is formed. 
     (Light-Emitting Chip Array) 
       FIG. 4  illustrates light distribution patterns formed on a screen by light from each light-emitting chip array (the first light-emitting chip array  40 , the second light-emitting chip array  50 , the third light-emitting chip array  60 , and the bottom light-emitting chip array  70 ). 
       FIG. 4( a )  illustrates the light distribution pattern formed on a screen when the first light-emitting chips  41  in the first light-emitting chip array  40  are all turned on;  FIG. 4( b )  illustrates the light distribution pattern formed on a screen when the second light-emitting chips  51  in the second light-emitting chip array  50  are all turned on;  FIG. 4( c )  illustrates the light distribution pattern formed on a screen when the third light-emitting chips  61  in the third light-emitting chip array  60  are all turned on; and  FIG. 4( d )  illustrates the light distribution pattern formed on a screen when the bottom light-emitting chips  71  in the bottom light-emitting chip array  70  are all turned on. 
     Note that, in  FIG. 4 , a VU-VL line indicates a vertical reference line on the screen, and an HL-HR line indicates a horizontal reference line on the screen. Similarly, in the subsequent drawings illustrating light distribution patterns on the screen, the VU-VL line indicates a vertical reference line on the screen, and the HL-HR line indicates the horizontal reference line on the screen. 
     As illustrated in  FIG. 3 , the first light-emitting chip array  40  is disposed on the substrate  30  such that the center of the first light-emitting chip array  40  in the horizontal direction (the X axis direction) is positioned on or near the lamp optical axis (see the Z axis). Note that the first light-emitting chip array  40  is disposed on the substrate  30  on or near the lamp optical axis (see the Z axis) in view of the vertical direction (the Y axis direction). 
     More specifically, the first light-emitting chip  41  positioned at the center of the first light-emitting chip array  40  in the horizontal direction (the X axis direction) is disposed on or near the lamp optical axis (see the Z axis) on the substrate  30 . With reference to the first light-emitting chip  41  at the center, 14 first light-emitting chips  41  are disposed at a constant pitch along the horizontal direction (the X axis direction) toward the left and right, respectively. 
     That is, the first light-emitting chip array  40  consists of a total of 29 first light-emitting chips  41 . Note that, with reference to the first light-emitting chip  41  positioned on or near the lamp optical axis (see the Z axis) of the first light-emitting chip array  40 , the first light-emitting chips  41  may be disposed along the horizontal direction toward the left and right, respectively, in different numbers. When all of the first light-emitting chips  41  of the first light-emitting chip array  40  are turned on, a light distribution pattern is formed that is substantially symmetrical about the vertical reference line (the VU-VL line) in the horizontal direction and extending across the horizontal reference line (the HL-HR line) in the vertical direction, as illustrated in  FIG. 4( a ) . 
     Note that the light distribution pattern illustrated in  FIG. 4( a )  is formed by the individual light distribution patterns formed by the light from the corresponding first light-emitting chips  41  overlapping in the horizontal direction with the light distribution patterns adjacent to each other. 
     Describing this in more detail, the individual light distribution pattern (see region P 1 ) formed by the light from a first light-emitting chip  41  positioned at the center of the first light-emitting chip array  40  in the horizontal direction is disposed on the vertical reference line (the VU-VL line); the individual light distribution pattern (see region P 2 ) formed by the light from a first light-emitting chip  41  immediately on the left of the first light-emitting chip  41  disposed at the center in the horizontal direction is positioned on the right of the vertical reference line (the VU-VL line) in the horizontal direction while overlapping the right-side portion of the light distribution pattern (see region P 1 ) disposed on the vertical reference line (the VU-VL line). 
     The individual light distribution pattern (see region P 3 ) formed by the light from a first light-emitting chip  41  immediately on the right of the first light-emitting chip  41  disposed at the center in the horizontal direction is disposed on the left of the vertical reference line (the VU-VL line) in the horizontal direction while overlapping the left-side portion of the light distribution pattern (see region P 1 ) disposed on the vertical reference line (the VU-VL line). Note that, in  FIG. 4( a ) , only the regions of the individual light distribution patterns formed by the light from the three first light-emitting chips  41  disposed at and near the center in the horizontal direction are indicated as a region P 1 , a region P 2 , and a region P 3 . Similarly, individual light distribution patterns formed by the light from other first light-emitting chips  41  disposed on the outer left and right sides the first light-emitting chips  41  disposed at and near the center reside adjacent to each other such that the individual light distribution patterns overlap with each other. 
     That is, the light from the first light-emitting chip  41  residing farthest right in the horizontal direction forms the farthest left portion of the light distribution pattern in the horizontal direction, and the light from the first light-emitting chip  41  residing farthest left in the horizontal direction forms the farthest right portion of the light distribution pattern in the horizontal direction. Thus, emission of light to a leading vehicle or an oncoming vehicle can be avoided by turning off the first light-emitting chips  41  corresponding to the position of the leading vehicle or the oncoming vehicle in the horizontal direction, thereby suppressing the generation of glare light. 
     The second light-emitting chip array  50  is disposed on the substrate  30  such that the center of the second light-emitting chip array  50  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) is disposed at a first distance D 1  vertically downward from the first light-emitting chip array  40 , as illustrated in  FIG. 3 . 
     The second light-emitting chip array  50  is also disposed on the substrate  30  such that the second light-emitting chip  51  at the center of the second light-emitting chip array  50  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis). With reference to the second light-emitting chip  51  disposed at the center, 14 second light-emitting chips  51  are disposed at a constant pitch along the horizontal direction (the X axis direction) toward the left and right, respectively. 
     That is, the second light-emitting chip array  50  also consists of a total of 29 second light-emitting chips  51 , like the first light-emitting chip array  40 . Note that, with reference to the second light-emitting chip  51  positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) of the second light-emitting chip array  50 , different numbers of the second light-emitting chips  51  may be disposed on the left and right sides in the horizontal direction, and/or the number of the second light-emitting chips  51  may be smaller than the number of the first light-emitting chips  41 . 
     When all of the second light-emitting chips  51  of the second light-emitting chip array  50  are turned on, like the first light-emitting chip array  40 , a light distribution pattern is formed that is substantially symmetrical in the horizontal direction about the vertical reference line (the VU-VL line), as illustrated in  FIG. 4( b ) . Since the second light-emitting chip array  50  is disposed at a large first distance D 1  (for example, approximately 0.94 mm) vertically downward from the first light-emitting chip array  40 , the lower edge of the light distribution pattern is positioned above the horizontal reference line (the HL-HR line). 
     Note that, like the first light-emitting chip array  40 , in the light distribution pattern illustrated in  FIG. 4( b ) , the individual light distribution patterns formed by the light from the second light-emitting chips  51  overlap the adjacent light distribution patterns in the horizontal direction. Thus, emission of light to a leading vehicle or an oncoming vehicle can be avoided by turning off the second light-emitting chips  51  corresponding to the position of the leading vehicle or the oncoming vehicle in the horizontal direction, thereby suppressing the generation of glare light. 
     Furthermore, the third light-emitting chip array  60  is disposed on the substrate  30  such that the center of the third light-emitting chip array  60  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) and is disposed at a second distance D 2  vertically downward from the second light-emitting chip array  50 , as illustrated in  FIG. 3 . 
     The third light-emitting chip array  60  is also disposed on the substrate  30  such that the third light-emitting chip  61  at the center of the third light-emitting chip array  60  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis). With reference to the third light-emitting chip  61  disposed at the center, 14 third light-emitting chips  61  are disposed at a constant pitch along the horizontal direction (the X axis direction) toward the left and right, respectively. 
     That is, the third light-emitting chip array  60  also consists of a total of 29 third light-emitting chips  61 , like the first light-emitting chip array  40  and the second light-emitting chip array  50 . Note that, with reference to the third light-emitting chips  61  disposed on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) of the third light-emitting chip array  60 , different numbers of the third light-emitting chips  61  may be disposed on the left and right sides in the horizontal direction, and/or the number of the third light-emitting chips  61  may be smaller than the number of the second light-emitting chips  51 . 
     When all of the third light-emitting chips  61  of the third light-emitting chip array  60  are turned on, like the first light-emitting chip array  40  and the second light-emitting chip array  50 , a light distribution pattern is formed that is substantially symmetrical in the horizontal direction about the vertical reference line (the VU-VL line), as illustrated in  FIG. 4( c ) . Since the third light-emitting chip array  60  is disposed only at a small second distance D 2  (for example, approximately 0.24 mm) vertically downward from the second light-emitting chip array  50 , the lower edge of the light distribution pattern is positioned slightly vertically above the light distribution pattern (see  FIG. 4( b ) ) formed by the light from the second light-emitting chip array  50 . 
     Note that, like the first light-emitting chip array  40  and the second light-emitting chip array  50 , in the light distribution pattern illustrated in  FIG. 4( c ) , the individual light distribution patterns formed by the light from the third light-emitting chips  61  overlap the adjacent light distribution patterns in the horizontal direction. Thus, emission of light to a leading vehicle or an oncoming vehicle can be avoided by turning off the third light-emitting chips  61  corresponding to the position of the leading vehicle or the oncoming vehicle in the horizontal direction, thereby suppressing the generation of glare light. 
     Here, the main light that acts as glare light to a leading vehicle or an oncoming vehicle is incident on the screen vertically above the horizontal reference line (the HL-HR line). The closer the leading vehicle or the oncoming vehicle is, the higher the position of the roof of the leading vehicle or the oncoming vehicle is on the vertically upward side of the screen. 
     In this embodiment, the positions of the lower edges of the light distribution patterns having lower edges disposed vertically above the horizontal reference line (the HL-HR line) on the screen slightly differ in the vertical direction. Thus, the light-emitting chips corresponding to the light distribution patterns having lower edges disposed vertically above the roof of the leading vehicle or the oncoming vehicle remain turned on, whereas the light-emitting chips corresponding to the light distribution patterns having lower edges disposed below the roof of the leading vehicle or the oncoming vehicle are turned off, thereby suppressing glare light emitted to the leading vehicle or the oncoming vehicle. 
     Similarly, the bottom light-emitting chip array  70  is also disposed on the substrate  30  such that the center of the bottom light-emitting chip array  70  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) and is disposed at a second distance D 2  vertically downward from the third light-emitting chip array  60 , as illustrated in  FIG. 3 . 
     Thus, when all of the bottom light-emitting chips  71  of the bottom light-emitting chip array  70  are turned on, the light distribution pattern is substantially symmetrical in the horizontal direction about the vertical reference line (the VU-VL line), like the first light-emitting chip array  40 , the second light-emitting chip array  50 , and the third light-emitting chip array  60 , as illustrated in  FIG. 4( d ) . Since the bottom light-emitting chip array  70  is disposed only at a small second distance D 2  (for example, approximately 0.24 mm) vertically downward from the third light-emitting chip array  60 , the lower edge of the light distribution pattern is positioned only slightly vertically above the lower edge of the light distribution pattern (see  FIG. 4( c ) ) formed by the light from the third light-emitting chip array  60 . 
     This allows fine control in accordance with the distance to the leading vehicle or the oncoming vehicle, as described in relation to the third light-emitting chip array  60 . 
     Note that the bottom light-emitting chip array  70  is also disposed on the substrate  30  such that the bottom light-emitting chip  71  at the center of the bottom light-emitting chip array  70  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis). With reference to the bottom light-emitting chip  71  disposed at the center, 14 bottom light-emitting chips  71  are disposed at a constant pitch along the horizontal direction (the X axis direction) to the left and right, respectively, and a total of 29 bottom light-emitting chips  71  are provided. However, with reference to the bottom light-emitting chip  71  disposed on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) of the bottom light-emitting chip array  70 , different numbers of the bottom light-emitting chips  71  may be disposed on the left and right sides in the horizontal direction, and/or the number of the bottom light-emitting chips  71  may be smaller than the number of the third light-emitting chips  61 . 
     It is preferred that a driving-beam light distribution pattern formed by multiplexing light distribution patterns (see  FIG. 4 ) formed of light from corresponding light-emitting chip arrays (the first light-emitting chip array  40 , the second light-emitting chip array  50 , the third light-emitting chip array  60 , and the bottom light-emitting chip array  70 ) has luminosity that smoothly attenuates in the vertically upward direction. 
     Thus, it is desirable to set the luminescence of the second light-emitting chips  51  of the second light-emitting chip array  50  lower than the luminescence of the first light-emitting chips  41  of the first light-emitting chip array  40 , the luminescence of the third light-emitting chips  61  of the third light-emitting chip array  60  lower than the luminescence of the second light-emitting chips  51  of the second light-emitting chip array  50 , and the luminescence of the bottom light-emitting chips  71  of the bottom light-emitting chip array  70  lower than the luminescence of the third light-emitting chips  61  of the third light-emitting chip array  60 . 
     For example, it is preferred that the electrical power supplied to the second light-emitting chips  51 , the third light-emitting chips  61 , and the bottom light-emitting chips  71  be reduced in order, such that, when the luminescence (output) of the first light-emitting chips  41  is set to 100%, the luminescence (output) of the second light-emitting chips  51  is set to approximately 50%, the luminescence (output) of the third light-emitting chips  61  is set to approximately 35%, and the luminescence (output) of the bottom light-emitting chips  71  is set to approximately 20%. 
       FIG. 5  illustrates a driving-beam light distribution pattern according to this embodiment on a screen, the driving-beam light distribution pattern being formed by multiplexing the light distribution patterns illustrated in  FIG. 4 . Note that the light distribution patterns are indicated by equal luminosity lines in  FIG. 5 . 
     As described above, the light-emitting chips (the first light-emitting chips  41 , the second light-emitting chips  51 , the third light-emitting chips  61 , and the bottom light-emitting chips  71 ) are in the same arrangement in the horizontal direction in the corresponding light-emitting chip arrays (the first light-emitting chip array  40 , the second light-emitting chip array  50 , the third light-emitting chip array  60 , and the bottom light-emitting chip array  70 ). Thus, the widths of the light distribution patterns in the horizontal direction are substantially the same, as illustrated in  FIG. 4 . 
     Also, as described above, the positions of the light distribution patterns on the screen are varied in the vertical direction to appropriately control the positions of the lower edges of the light distribution patterns. Thus, the driving-beam light distribution pattern formed by the multiplexing the light distribution patterns illustrated in  FIG. 4  has a rectangular shape that is wide in the horizontal and vertical directions, as illustrated in  FIG. 5 , and achieves a satisfactory driving-beam light distribution pattern having the highest luminescence at the center. 
       FIG. 6  illustrates a case in which some of the light-emitting chips are turned off to respond to a leading vehicle or an oncoming vehicle. According to this embodiment, light distribution can be controlled to prevent a region C corresponding to a leading vehicle or an oncoming vehicle from being irradiated with light, as illustrated in  FIG. 6 , because light-emitting chip arrays are disposed in other rows in the vertical direction. 
     In specific, the region C includes a small substantially rectangular segment C 1  on the left side in the horizontal direction and a large substantially rectangular segment C 2  adjoining the right side of the small substantially rectangular segment C 1  in the horizontal direction. The small substantially rectangular segment C 1  corresponds to a leading vehicle approximately 100 m ahead and is not irradiated with light. The large substantially rectangular segment C 2  corresponds to an oncoming vehicle approximately 50 m ahead and is not irradiated with light. 
     In this way, light can be emitted above a leading vehicle or an oncoming vehicle in the vertical direction while the leading vehicle or the oncoming vehicle is prevented from being irradiated with light. This allows suppression of glare light emitted to the leading vehicle or the oncoming vehicle while achieving control of a driving-beam light distribution pattern having good visibility. 
     In particular, in this embodiment, the use of a multilayer wiring board as the substrate  30  prevents the intervals of the light-emitting chips from being limited due to wiring provided on the substrate  30 , thereby achieving a distance (width of gaps) between light-emitting chips adjacent to each other in the horizontal direction of 0.2 mm or less (in specific, approximately 0.1 mm). Thus, the intervals of turning off the driving-beam light distribution pattern in the horizontal direction can be finely controlled, thereby achieving high controllability. 
     Second Embodiment 
     A vehicular lamp according to a second embodiment of the present invention will now be described with reference to  FIGS. 7 and 8 . The basic configuration of the second embodiment is the same as that of the first embodiment. Thus, descriptions of the components that differ from those of the first embodiment will be mainly provided, and descriptions of similar components may be omitted. 
       FIG. 7  illustrates the configuration of the second embodiment of the present invention. The bottom portion of  FIG. 7  corresponds to  FIG. 3 , and the top portion of  FIG. 7  corresponds to  FIG. 5 . As illustrated in  FIG. 7 , also in the second embodiment, a light source unit  20  includes a first light-emitting chip array  40 , a second light-emitting chip array  50 , and a third light-emitting chip array  60 . Furthermore, the positional relation of the first light-emitting chip array  40 , the second light-emitting chip array  50 , and the third light-emitting chip array  60  on the substrate  30  (the positional relation in the horizontal direction (see the X axis) and the vertical direction (see the Y axis)) is also the same as that of the first embodiment. 
     Note that the arrangement of first light-emitting chips  41  in the first light-emitting chip array  40 , second light-emitting chips  51  in the second light-emitting chip array  50 , and third light-emitting chips  61  in the third light-emitting chip array  60  is also the same as that of the first embodiment. 
     Furthermore, the use of a multilayer wiring board, such as a buildup board, as a substrate  30  is the same as that of the first embodiment. 
     In contrast, in the second embodiment, the bottom light-emitting chip array  70  according to the first embodiment is replaced with a fourth light-emitting chip array  80  including many semiconductor-type fourth light-emitting chips  81  arrayed along the horizontal direction on a substrate  30  of a light source unit  20 . 
     Note that LED chips are used as the fourth light-emitting chips  81 , as in the first embodiment, but alternatively, semiconductor-type light-emitting chips, such as LD chips, may be used. 
     The fourth light-emitting chip array  80  is disposed on the substrate  30  such that the center of the fourth light-emitting chip array  80  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis), and the fourth light-emitting chip  81  disposed at the center of the fourth light-emitting chip array  80  in the horizontal direction (the X axis direction) is positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis), as illustrated in  FIG. 7 . 
     Furthermore, also in the fourth light-emitting chip array  80 , the fourth light-emitting chip  81  are disposed at a constant pitch along the horizontal direction (the X axis direction) and in the same number on the left and right sides (in the horizontal direction) with reference to the fourth light-emitting chip  81  disposed at the center of the fourth light-emitting chip array  80  in the horizontal direction (the X axis direction). The number of the fourth light-emitting chip  81  is smaller than that of the first light-emitting chips  41 . 
     However, as described below, in the fourth light-emitting chip array  80 , the fourth light-emitting chips  81  may not necessarily be disposed in the same number in the horizontal direction with reference to the vertical line (see the Y axis), and thus, the center of the fourth light-emitting chip array  80  in the horizontal direction (the X axis direction) is not always positioned on or near the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis). 
     In the second embodiment having such a configuration, when all of the light-emitting chips disposed in the light source unit  20  are turned on, the light distribution pattern such as that illustrated in  FIG. 7  is formed. 
     In specific, as a result of the fourth light-emitting chip array  80 , a portion (see the hatched portion) corresponding to light distributed below the horizontal reference line (the HL-HR line) and lower than the driving-beam light distribution pattern according to the first embodiment (see  FIG. 5 ) is formed close to the vertical line (the VU-VL line). 
     The light distributed in the lower portion in this way can form a marking light distribution pattern ML (see  FIG. 8 ) that indicates the presence of a pedestrian HM to the driver, as described below. Note that the marking light distribution pattern ML (see  FIG. 8 ) is not only used to indicate the presence of a pedestrian to the driver but may also be used to indicate the presence of the vehicle to the pedestrian. 
       FIG. 8  illustrates a marking light distribution pattern ML.  FIG. 8  illustrates a state in which a vehicle is driving with low beam lamps that are provided in the vehicular lamps as separated units turned on and presumes a state in which a pedestrian HM is walking along a side walk in front and on the right side of the vehicle. 
     That is, most of the light-emitting chips of the light source unit  20  are turned off. In such a state, when a detection device (for example, a motion sensor) installed in the vehicle detects the pedestrian HM, the fourth light-emitting chips  81  that can emit light onto or near the detected position among the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  are turned on to form a marking light distribution pattern ML, as illustrated in  FIG. 8 . 
     The marking light distribution pattern ML is formed by the vehicular lamp closer to the pedestrian HM among the left and right vehicular lamps. Describing this in more detail, in  FIG. 8 , the marking light distribution pattern ML is formed by the right vehicular lamp because the pedestrian HM is present on the side walk adjacent to the oncoming lane. 
       FIG. 7  illustrates a relation in which when the light from the fourth light-emitting chips  81  disposed on the right side in the horizontal direction with reference to the vertical reference line (see the Y axis) extending through the lamp optical axis (see the Z axis) among the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  passes through the lens  21  (see  FIG. 2 ), the light is incident on the screen on the left side in the horizontal direction of the vertical reference line (the VU-VL line), and when the light from the fourth light-emitting chips  81  positioned on the left side in the horizontal direction with reference to the vertical reference line (see the Y axis) extending through the lamp optical axis (see the Z axis) passes through the lens  21  (see  FIG. 2 ), the light is incident on the screen on the right side in the horizontal direction of the vertical reference line (the VU-VL line). 
     However, in the example illustrated in  FIG. 8 , the pedestrian HM resides on the right side in the horizontal direction. Thus, the appropriate fourth light-emitting chips  81  on the left side in the horizontal direction with reference to the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) among the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  of the right vehicular lamp are turned on to form the marking light distribution pattern ML. 
     By forming such a marking light distribution pattern ML, the driver can readily recognize the presence of a pedestrian, and in contrast, the pedestrian can recognize the presence of the vehicle through the emitted light. 
     However, when a pedestrian HM is on the right side in the horizontal direction, a marking light distribution pattern ML is emitted from the right vehicular lamp, and when a pedestrian HM is on the left side in the horizontal direction, a marking light distribution pattern ML is emitted from the left vehicular lamp. Thus, in the case where the light source units  20  are designed individually for the left and right vehicular lamps, the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  do not have to be disposed symmetrically about the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis), as illustrated in  FIG. 7 . 
     That is, to provide standardized light source units  20  for the left and right vehicular lamps, the light source units  20  each may include the fourth light-emitting chip array  80  illustrated in  FIG. 7 . To provide light source units  20  having different designs for the left and right vehicular lamps, the light source units  20  may be configured as described below. 
     As also described above, when a pedestrian is on the right side in the horizontal direction, a marking light distribution pattern ML is formed by the right vehicular lamp. The fourth light-emitting chips  81  that emit light in the corresponding direction are the fourth light-emitting chips  81  positioned on the left side in the horizontal direction with reference to the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) among the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  illustrated in  FIG. 7 . 
     Note that the left side in the horizontal direction of the vehicular lamp on the right side of the vehicle is the inner side of the vehicle. 
     However, the vehicular lamps are offset to the left and right relative to the center of the vehicle. Thus, when a pedestrian is in front of the center of the vehicle, the vehicular lamp should be able to emit a marking light distribution pattern ML toward the center. 
     Thus, the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  to be provided on the light source unit  20  of the right vehicular lamp should be the fourth light-emitting chips  81  disposed in the range L 1  in  FIG. 7 , i.e., the fourth light-emitting chip  81  on the immediate right in the horizontal direction (the X axis direction) of the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) and all the fourth light-emitting chips  81  arrayed to the left therefrom. 
     However, in some cases, the fourth light-emitting chips  81  may include the fourth light-emitting chip  81  on the second right in the horizontal direction of the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) and all the fourth light-emitting chips  81  arrayed to the left therefrom. 
     In such a case also, a larger number of fourth light-emitting chips  81  can be disposed on the left side (i.e., the inner side of the vehicle) of the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) in the horizontal direction than on the right side in the horizontal direction, to provide a light source unit  20  for the right vehicular lamp. 
     Similarly, a larger number of fourth light-emitting chips  81  can be disposed on the right side of the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) in the horizontal direction than on the left side in the horizontal direction, to provide a light source unit  20  for the left vehicular lamp (for example, see the fourth light-emitting chips  81  in the range R 1  in  FIG. 7 ). Note that the right side in the horizontal direction of the vehicular lamp on the left side of the vehicle is the inner side of the vehicle. 
     Thus, the left and right vehicular lamps, which include the fourth light-emitting chips  81  by different numbers on the left and right sides of the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis) in the horizontal direction, should each have a larger number of fourth light-emitting chips  81  on the inner side of the vehicle than the outer side of the vehicle relative to the vertical line (see the Y axis) extending through the lamp optical axis (see the Z axis). 
     It is preferred that the marking light distribution pattern ML, which is emitted toward a pedestrian HM, a bicycle, a motorcycle, etc., does not act as glare light. Thus, the fourth light-emitting chip array  80  desirably emits light to the screen in a region below the horizontal reference line (the HL-HR line) (more desirably, a region on or below the horizontal reference line (the HL-HR line) on the screen). 
     In specific, it is preferred that when light from the fourth light-emitting chip array  80  passes through the lens  21  (see  FIG. 2 ), the light from the fourth light-emitting chips  81  emitted such that the center in the vertical direction of the light distribution pattern formed by the light from the fourth light-emitting chip array  80  (the center of the vertical width of the light distribution pattern) is disposed below the horizontal reference line (the HL-HR line) on the screen. That is, it is desirable that the fourth light-emitting chip array  80  be disposed on the upper side of the substrate  30  in the vertical direction so that light can be emitted to the upper side of the lens  21  in the vertical direction and thereby emitted below the horizontal reference line (the HL-HR line) on the screen. 
     In the above-described examples, the only light-emitting chip array that forms a marking light distribution pattern ML is the fourth light-emitting chip array  80 . Additional light-emitting chip arrays may be provided to form further marking light distribution patterns ML. 
     In specific, the light source unit  20  may include at least one upper light-emitting chip array  90  (see  FIG. 9 ) disposed above and apart from the fourth light-emitting chip array  80  in the vertical direction on the substrate  30 . 
     In such a case, the further provided upper light-emitting chip array  90  may include upper light-emitting chips  91  having the same arrangement in the horizontal direction (the X axis direction) on the substrate  30  as that of the fourth light-emitting chips  81  of the fourth light-emitting chip array  80 . That is, a fourth light-emitting chip array identical to the fourth light-emitting chip array  80  may be further provided above the fourth light-emitting chip array  80  in the vertical direction. 
       FIG. 9  is a plan view of a light source unit  20  according to the second embodiment including an upper light-emitting chip array  90 . As illustrated in  FIG. 9 , for example, three upper light-emitting chip arrays  90  having the same configuration as that of the fourth light-emitting chip array  80  may disposed on the upper side in the vertical direction, and the curvature of the incident face or the emission face of the lens  21  may be slightly adjusted. Then, the upper light-emitting chips  91  of the upper light-emitting chip arrays  90  can be turned on at different timings in sequence from the uppermost ones such that after the upper light-emitting chips  91  adjacent to the fourth light-emitting chip array  80  are turned on, the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  are finally turned on. In this way, spots of light can be shifted from the vehicle to approach the pedestrian. This dynamic movement of the light enables even more ready recognition of the pedestrian by the driver. 
     Note that the dynamic movement of light also enables even more ready recognition of the vehicle by the pedestrian. 
     Although the present invention has been described based on specific embodiments, the present invention is not limited to above embodiment. For example, when the driving-beam light distribution pattern is formed in the second embodiment, the fourth light-emitting chips  81  of the fourth light-emitting chip array  80  may be turned off while the light-emitting chips (the first light-emitting chips  41 , the second light-emitting chips  51 , and the third light-emitting chips  61 ) of the first light-emitting chip array  40 , the second light-emitting chip array  50 , and the third light-emitting chip array  60  may be turned on. 
     Furthermore, in the second embodiment, a bottom light-emitting chip array  70  may be further provided below the third light-emitting chip array  60  in the vertical direction, as in the first embodiment. 
     Furthermore, in the second embodiment, the second light-emitting chip array  50  and the third light-emitting chip array  60  may be omitted, and the light source unit  20  may include merely the first light-emitting chip array  40  and the fourth light-emitting chip array  80 . In such a case, a driving-beam light distribution pattern may be formed only by the first light-emitting chip array  40 , and a marking light distribution pattern ML may be formed by the fourth light-emitting chip array  80 . 
     Furthermore, in the above-described embodiments, the light-emitting chips (the first light-emitting chips  41 , the second light-emitting chips  51 , the third light-emitting chips  61 , the bottom light-emitting chips  71 , the fourth light-emitting chips  81 , and the upper light-emitting chips  91 ) in the respective light-emitting chip arrays (the first light-emitting chip array  40 , the second light-emitting chip array  50 , the third light-emitting chip array  60 , the bottom light-emitting chip array  70 , the fourth light-emitting chip array  80 , and the upper light-emitting chip array  90 ) are arrayed in the horizontal direction at a constant pitch. Alternatively, the pitch of the light-emitting chips in the horizontal direction may differ for each light-emitting chip array or the light-emitting chips may be arrayed at different pitches in the same light-emitting chip array. 
     Although the present invention is not limited to above embodiment. Modifications and improvements that do not depart from the technical aspects are also included in the technical scope of the invention, and this is evident from the description of the scope of the claims for patent. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           10  lamp unit 
           20  light source unit 
           21  lens 
           30  substrate 
           40  first light-emitting chip array 
           41  first light-emitting chip 
           50  second light-emitting chip array 
           51  second light-emitting chip 
           60  third light-emitting chip array 
           61  third light-emitting chip 
           61  third light-emitting chip 
           70  bottom light-emitting chip array 
           71  bottom light-emitting chip 
           80  fourth light-emitting chip array 
           81  fourth light-emitting chip 
           90  upper light-emitting chip array 
           91  upper light-emitting chip 
         C region 
         C 1  small substantially rectangular segment 
         C 2  large substantially rectangular segment 
         D 1  first distance 
         D 2  second distance 
         HM pedestrian 
         ML marking light distribution pattern 
           101 L,  101 R vehicular front light 
           102  vehicle