JP2013084530A - Vehicular headlamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular headlamp that can alleviate a load of an actuator for driving a reflection part of a light deflection unit and improving durability of the actuator as well.SOLUTION: Inside piezoelectric actuators 31, 32 and outside piezoelectric actuators 51, 52 rotate reflection part 2 where light from a laser light source 11 enters around an X axis and a Y axis respectively and scan an irradiation region frontward of the vehicle in a right-and-left direction and an up-and-down direction by the reflection light from the reflection part 2. A control part 12 controls the inside piezoelectric actuators 31, 32 and the outside piezoelectric actuators 51, 52 so that an up-and-down direction scanning frequency (a rotation frequency around the Y axis) may become larger than the right-and-left direction scanning frequency (a rotation frequency around the X axis).

Description

  The present invention relates to a vehicle headlamp that irradiates light to an irradiation area in front of a vehicle.

  Conventionally, a vehicular headlamp that illuminates an irradiation area by scanning the irradiation area in front of the vehicle with spot light is known. For example, a scanning vehicle headlamp described in Patent Literature 1 includes a light source, a reflection unit that emits reflected light reflected from incident light from the light source, and an irradiation area in front of the vehicle by reflected light. And an actuator that rotates the reflecting portion around the first and second axes so as to scan in the vertical direction and the horizontal direction, respectively (FIGS. 12 and 13 of Patent Document 1).

  In the above-mentioned vehicle headlamp, the main scanning direction (scanning direction in which the scanning frequency is increased) and the sub-scanning direction (scanning direction in which the scanning frequency is decreased) are set to the left and right directions and the up and down direction, respectively (patent) Reference 1: Horizontal stripes in FIG.

JP 2009-48786 A

  In the conventional scanning vehicle headlamp disclosed in Patent Document 1, the main scanning direction of the scanning light, that is, the operating direction in which the actuator must operate the reflecting portion at a high speed, is the rotation angle range of the reflecting portion. Since it is set in a large left-right direction, the load on the actuator increases, and as a result, there is a problem in that the durability of the actuator decreases.

  The objective of this invention is providing the vehicle headlamp which improved the durability of an actuator while reducing the burden of the actuator which drives a reflection part.

  The present invention provides a light source, a reflection unit that emits reflected light reflected from incident light from the light source to the front of the vehicle, and an irradiation area in front of the vehicle that scans the reflected light in the vertical and horizontal directions, respectively. An actuator for rotating the reflecting portions around the first and second axes, respectively, and an actuator control portion for controlling the actuator so that the vertical scanning frequency of the reflected light is higher than the horizontal scanning frequency. It is characterized by providing.

  According to the present invention, the main scanning direction of the reflected light becomes the vertical direction by controlling the actuator so that the vertical scanning frequency of the reflected light is higher than the horizontal scanning frequency. As a result, the actuator only needs to operate at a high speed in the vertical direction in which the rotation angle range of the reflecting portion is small, so the burden on the actuator is reduced and the durability of the actuator is improved.

  By the way, in the horizontal irradiation area, the farther away, the irradiation area of the reflected light per unit rotation angle of the reflection part around the vertical rotation axis increases, so that the illuminance in such an irradiation area is made uniform. It is necessary to reduce the rotation speed of the reflecting portion around the vertical rotation axis as the reflected light irradiates the far part of the irradiation region. However, it is difficult to control the mechanical rotation speed of the reflecting portion with high accuracy.

  Therefore, if the irradiation amount in the distant part is increased by controlling the light amount of the light source, the illuminance at the irradiation destination can be controlled without increasing or decreasing the rotational speed of the mechanical movement, so that the control becomes simple. However, when the main scanning direction of the scanning light is the left-right direction as in the prior art, the time during which the scanning light stays in the distant portion is relatively long, so the time for maintaining the light source at a large amount of light becomes long. For this reason, the emitted-heat amount of a light source increases and the light emission efficiency of a light source is reduced. Increasing the energization amount of the light source to compensate for this tends to lead to a vicious circle in which the heat generation amount of the light source further increases and the light emission efficiency decreases.

  This problem is that according to the vehicle headlamp of the present invention, in the scanning period of the vertical direction by reflected light, the scanning period in the upper area of the irradiation area is more reflective than the scanning period in the lower area of the irradiation area. It is solved by controlling so that the amount of light increases.

  That is, in the vehicle headlamp according to the present invention, in the vertical scanning period by the reflected light, the amount of the reflected light increases in the scanning period in the upper range of the irradiation area than in the scanning period in the lower range of the irradiation area. It is preferable to include a light amount control unit that controls the light amount of the light source. According to this, the illuminance of the irradiation region can be increased by increasing the illuminance of the far region portion of the irradiation region without performing control to increase or decrease the rotation speed of the reflecting portion around the first axis according to the irradiation direction of the reflected light. Can be made uniform.

  In addition, by setting the main scanning direction of the reflected light in the vertical direction, the period in which the amount of light from the light source is increased as the period in which the reflected light illuminates the distant part of the irradiation area, and the period in which the reflected light irradiates in the vicinity of the irradiation area Since the switching frequency with the period in which the light quantity of the light source is reduced increases, each period in which the light source is continuously increased in light quantity is shortened. As a result, the heat generation of the light source is reduced, so that a decrease in light emission efficiency is avoided. In this way, it is possible to increase the illuminance in the far part of the irradiation region while avoiding the decrease in light emission efficiency.

  In the present invention, the actuator control unit controls the actuator so that the upper turning point of the vertical scanning is above the cut line of the irradiation area, and the light amount control unit performs the irradiation in each vertical scanning cycle. It is preferable to turn off the light source in the vertical scanning period in the range above the cut line of the region.

  Here, the cut line may not be set to a uniform height regardless of the position in the left-right direction, and may be set so that the height changes according to the position in the left-right direction. The cut line is generated by switching the light source on and off in response to the rotation angle around the first axis, regardless of the control of the upper turning angle of the reflecting portion by the actuator. Thereby, it is possible to generate an arbitrary cut line while fixing the rotation angle range of the reflecting portion around the first axis and simplifying the control of the actuator.

  In the present invention, the light amount control unit can control the light amount of the light source based on an increase or decrease of a current value in continuous energization to the light source or an increase or decrease of a pulse width of a discontinuous energization pulse of the light source. Thereby, the light quantity of a light source can be controlled smoothly.

The schematic diagram of the vehicle headlamp. Explanatory drawing about the scanning angle of the scanning light radiate | emitted from a vehicle headlamp. The detailed structural drawing of an optical deflector. The figure which shows the scanning pattern of the reflected light from a reflection part. The figure which shows the relationship between the light quantity of the laser light source in the vehicle headlamp, and the up-and-down angle of reflected light. Explanatory drawing about the control which produces | generates arbitrary cut lines by the on / off control of a laser light source.

  In FIG. 1, the main configuration of the vehicle headlamp 10 will be described. The vehicle headlamps 10 are respectively arranged on the left and right of the front portion of the vehicle toward the front of the vehicle (not shown). This controls the rotation angle of the optical deflector 1, the laser light source 11 that emits laser light to the reflection unit 2 of the optical deflector 1, the light amount control unit that controls the light amount of the laser light source 11, and the reflection unit 2. And a control unit 12 as an actuator control unit.

  As will be described later, the reflecting unit 2 rotates around the X axis and the Y axis that are perpendicular to each other, and determines the direction of the reflected light reflected from the incident light from the laser light source 11 with respect to the irradiation area in front of the vehicle. It is changed up, down, left, and right in the cycle. The X axis and the Y axis correspond to the second and first axis lines of the present invention, respectively.

  In FIG. 2, the scanning angle of the spot light emitted from the vehicle headlamp 10 will be described. The spot light from the vehicle headlamp 10 is highly directional light emitted from the laser light source 11 and is reflected light reflected by the reflecting portion 2 of the optical deflector 1. That's it.

FIG. 2A shows the scanning angle range of the reflected light in the left-right direction when the vehicle headlamp 10 is viewed from above. The left-right angle α is defined as an angle around a vertical line passing through a reflection point of incident light in the vehicle headlamp 10, where α = 0 ° is the left side of the vehicle headlamp 10 and the positive direction of α. Is clockwise. In this case, α = 90 ° is straight ahead of the vehicle headlamp 10, and α = 180 ° is right of the vehicle headlamp 10. α _L and α _R are the left and right angles α when the reflected light is directed to the left and right sides, respectively. The scanning angle range of the reflected light in the left-right direction is set to α _L (= 65 °) to α _R (= 115 °), and is 50 ° centering on α = 90 °.

FIG. 2B shows the scanning angle range of the reflected light in the vertical direction when the vehicle headlamp 10 is viewed from the side. The right side of FIG. 2B is the front of the vehicle. The vertical angle β is defined as an angle around a horizontal line passing through a reflection point of incident light in the vehicle headlamp 10, β = 0 ° is directly below the vertical direction, and the positive direction of β is counterclockwise. . In this case, the straight front of the vehicle headlamp 10 is β = 90 °. β _L and β _U are vertical angles β when the reflected light is directed to the lowermost side and the uppermost side, respectively. The vertical scanning angle range of the reflected light is 10 ° from β _L (= 80 °) to β _U (= 90 °).

  Thus, the scanning angle of the reflected light emitted from the vehicle headlamp 10 toward the front irradiation area is 50 ° in the left-right direction, whereas it is 10 ° in the vertical direction, and the vertical direction is It is much smaller than the horizontal direction.

Α _L , α _R , β _L , and β _U define the left and right and upper and lower boundaries of the irradiation area when the laser light source 11 is energized and the reflected light is actually emitted forward of the vehicle. It is an angle to do. α _{L to} α _R and β _{L to} β _U are the left and right of the rotation angle range of the reflection unit 2 in the normal rotation control of the reflection unit 2 (for example, rotation control for performing scanning in FIG. 4 described later). And the angle range associated with the upper and lower rotation angle ranges, but rotation control of the reflector 2 with on / off control of the laser light source 11 (example: rotation control for performing scanning in FIG. 6 described later). Then, it becomes narrower than the angle range associated with the left and right and the upper and lower rotation angle ranges of the rotation angle range of the reflection unit 2.

  A specific configuration of the optical deflector 1 will be described with reference to FIG. In FIG. 3, the optical deflector 1 is illustrated in a horizontally long shape, that is, although the X axis is illustrated in the horizontal direction and the Y axis is illustrated in the vertical direction, the light in the vehicle headlamp 10 is illustrated. In actual deployment of the deflector 1, as shown in FIG. That is, in the actual deployment of the optical deflector 1, the Y axis is generally in the horizontal direction, and the X axis is generally in the vertical direction.

  The optical deflector 1 includes a reflection portion 2 as a mirror, a pair of inner piezoelectric actuators 31 and 32, an inner support portion 4, a pair of outer piezoelectric actuators 51 and 52, and an outer support portion 6.

  The reflection unit 2 includes a rectangular reflection surface 2a that reflects incident light, and a rectangular reflection surface support 2b that supports the reflection surface 2a. The reflecting surface 2a is formed by processing a metal thin film on the reflecting surface support 2b using a semiconductor planar process.

  The thickness of the metal thin film is, for example, about 100 to 500 nm. The metal thin film is formed by, for example, a sputtering method or an electron beam evaporation method. The reflective surface support 2b is formed of a silicon substrate.

  The reflecting portion 2 is rotated around the X axis and the Y axis that have an intersection at the center of the reflecting portion 2 and are orthogonal to each other and extend in the surface direction of the reflecting portion 2 by a support structure described in detail later. It comes to move. Since the optical deflector 1 is arranged vertically as shown in FIG. 1, the left-right angle α of the reflected light increases or decreases when the reflecting unit 2 reciprocates around the X axis, and the reflecting unit 2 Is reciprocatingly rotated around the Y axis, the vertical angle β of the reflected light is increased or decreased.

  The inner piezoelectric actuators 31 and 32 are arranged to face each other with the reflecting portion 2 interposed therebetween. The inner piezoelectric actuators 31 and 32 have their tip portions connected to a pair of opposing sides of the reflecting portion 2, respectively. The side of the connected reflection unit 2 is a side orthogonal to the Y axis.

  The inner support portion 4 is formed in a rectangular frame shape, and is provided so as to surround the reflection portion 2 and the inner piezoelectric actuators 31 and 32. The inner support portion 4 is connected to respective end portions (base end portions) of the inner piezoelectric actuators 31 and 32 on the side to which the reflecting portion 2 is not connected, and the reflecting portion 2 is interposed via the inner piezoelectric actuators 31 and 32. Support.

  The outer piezoelectric actuators 51 and 52 are disposed to face each other with the inner support portion 4 interposed therebetween. The outer piezoelectric actuators 51 and 52 are connected at their tips to a pair of opposing sides in a direction parallel to the Y axis of the inner support 4.

  The outer support portion 6 is formed in a rectangular frame shape, and is provided so as to surround the inner support portion 4 and the outer piezoelectric actuators 51 and 52. A pair of other ends of the outer piezoelectric actuators 51 and 52 on the side not connected to the inner support portion 4 are connected to the outer support portion 6. Thus, the outer support portion 6 supports the inner support portion 4 via the outer piezoelectric actuators 51 and 52.

  The inner piezoelectric actuators 31 and 32 will be described. The inner piezoelectric actuators 31 and 32 are simply arranged symmetrically on the opposite sides in the vertical direction (up and down in FIG. 3) with respect to the reflecting portion 2, and the structure is the same. Only the inner piezoelectric actuator 31 will be described. The inner piezoelectric cantilevers 32A to 32D of the inner piezoelectric actuator 32 correspond to the inner piezoelectric cantilevers 31A to 31D of the inner piezoelectric actuator 31, respectively.

  The inner piezoelectric cantilevers 31 </ b> A to 31 </ b> D are adjacent to each other so that the length directions thereof are the same, and are arranged side by side at a predetermined interval so that the reflecting portion 2 can swing around the Y axis. The inner piezoelectric cantilevers 31 </ b> A to 31 </ b> D are connected so as to be folded back with respect to the adjacent piezoelectric cantilevers.

  As described above, the inner piezoelectric cantilever 31A to 31D forming the inner piezoelectric actuator 31 is formed in a so-called meander shape.

  An inner piezoelectric cantilever (hereinafter referred to as a “first inner piezoelectric cantilever”) 31A disposed on the reflecting portion 2 side of the inner piezoelectric cantilevers 31A to 31D is an adjacent inner piezoelectric cantilever (hereinafter referred to as a “second piezoelectric cantilever”). One end on the side not connected to 31B (referred to as “inner piezoelectric cantilever”) is connected to the outer peripheral portion of the reflecting portion 2.

  Similarly, an inner piezoelectric cantilever 31D (hereinafter referred to as a “fourth inner piezoelectric cantilever”) 31D disposed on the inner support 4 side of the inner piezoelectric cantilevers 31A to 31D is an adjacent inner piezoelectric cantilever (hereinafter referred to as “the fourth inner piezoelectric cantilever”). One end of the side not connected to 31C (referred to as “third inner piezoelectric cantilever”) is connected to the inner peripheral portion of the inner support portion 4.

  Thereby, the reflecting portion 2 can swing around the Y axis with respect to the inner support portion 4 by bending deformation of the inner piezoelectric cantilevers 31A to 31D and 32A to 32D constituting the inner piezoelectric actuators 31 and 32. .

  Next, the outer piezoelectric actuators 51 and 52 will be described. The outer piezoelectric actuators 51 and 52 are merely arranged symmetrically on the opposite sides in the left and right (left and right in FIG. 3) direction with respect to the reflecting portion 2, and the structure is the same. Only the outer piezoelectric actuator 51 will be described. The outer piezoelectric cantilevers 52A to 52D of the outer piezoelectric actuator 52 correspond to the outer piezoelectric cantilevers 51A to 51D of the outer piezoelectric actuator 51, respectively.

  The outer piezoelectric cantilevers 51 </ b> A to 51 </ b> D are adjacent to each other so that the length directions thereof are the same, and are arranged side by side at a predetermined interval so that the reflecting portion 2 can swing around the X axis. The outer piezoelectric cantilevers 51 </ b> A to 51 </ b> D are connected so as to be folded back with respect to the adjacent piezoelectric cantilevers.

  As described above, the outer piezoelectric actuator 51 has the outer piezoelectric cantilevers 51A to 51D forming the so-called meander shape.

  A cantilever (hereinafter referred to as a “first outer piezoelectric cantilever”) 51A disposed on the reflecting portion 2 side (the inner support portion 4 side) of the outer piezoelectric cantilevers 51A to 51D is an adjacent outer piezoelectric cantilever (hereinafter referred to as “first outer piezoelectric cantilever”). (Referred to as “second outer piezoelectric cantilever”). One end of the side that is not connected to 51B is connected to the outer peripheral portion of the inner support portion 4.

  Similarly, a piezoelectric cantilever (hereinafter referred to as a “fourth outer piezoelectric cantilever”) 51D disposed on the outer support portion 6 side of the outer piezoelectric cantilevers 51A to 51D is an adjacent outer piezoelectric cantilever (hereinafter referred to as “the fourth outer piezoelectric cantilever”). One end of the side that is not connected to 51C (referred to as “third outer piezoelectric cantilever”) is connected to the inner peripheral portion of the outer support portion 6.

  Accordingly, the inner support portion 4 can swing around the X axis with respect to the outer support portion 6 by bending deformation of the outer piezoelectric cantilevers 51A to 51D and 52A to 52D constituting the outer piezoelectric actuators 51 and 52. Yes.

  In the optical deflector 1 of the present embodiment, the inner piezoelectric actuators 31 and 32 and the outer piezoelectric actuators 51 and 52 are each composed of four piezoelectric cantilevers, but the number of piezoelectric cantilevers is not limited to this. Absent.

  The plurality of electrode pads 61 and 62 are respectively disposed on the left side portion and the right side portion of the lower side of the outer support portion 6. The electrode pad 61 energizes each electrode part of the inner piezoelectric cantilevers 31A to 31D and the outer piezoelectric cantilevers 51A to 51D. The electrode pad 62 energizes the electrode portions of the inner piezoelectric cantilevers 32A to 32D and the outer piezoelectric cantilevers 52A to 52D.

  Each piezoelectric cantilever has a structure in which a lower electrode, a piezoelectric body, and an upper electrode are laminated on a support layer as a strain generating body (cantilever main body). When the drive voltage associated with each piezoelectric cantilever is applied between the upper electrode and the lower electrode associated with each piezoelectric cantilever via the electrode pads 61 and 62, the applied upper electrode The piezoelectric body laminated between the first electrode and the lower electrode and associated with each piezoelectric cantilever is bent and deformed by piezoelectric driving. Thus, the support body (piezoelectric cantilever) corresponding to the bent piezoelectric body is bent and deformed.

  Next, the operation of the optical deflector 1 will be described. First, the case where the reflecting portion 2 is swung around the Y axis with respect to the inner support portion 4 by the inner piezoelectric actuators 31 and 32 will be described.

  In this case, the control unit 12 applies a driving voltage to the inner piezoelectric actuators 31 and 32 via the electrode pads 61 and 62 of the optical deflector 1. Specifically, in one inner piezoelectric actuator 31, the controller 12 drives the odd-numbered inner piezoelectric cantilevers 31A and 31C by applying the first voltage Vy1 to the corresponding electrode. At the same time, the control unit 12 drives the even-numbered inner piezoelectric cantilevers 31B and 31D by applying the second voltage Vy2 to the corresponding electrodes in one inner piezoelectric actuator 31.

  Further, in the other inner piezoelectric actuator 32, the controller 12 drives the odd-numbered inner piezoelectric cantilevers 32A and 32C by applying the first voltage Vy1 to the corresponding electrode. At the same time, in the other inner piezoelectric actuator 32, the controller 12 drives the even-numbered inner piezoelectric cantilevers 32B and 32D by applying the second voltage Vy2 to the corresponding electrodes.

  Here, the first voltage Vy1 and the second voltage Vy2 are alternating voltages (for example, a sine wave, a sawtooth wave, etc.) that have opposite phases or shifted phases. At this time, the oscillation voltage components of the first voltage Vy1 and the second voltage Vy2 are odd-numbered in the vertical direction of the inner piezoelectric actuators 31 and 32 (upward direction U in FIG. 3 and the downward direction opposite thereto). The inner piezoelectric cantilevers 31A, 31C, 32A, 32C and the even-numbered inner piezoelectric cantilevers 31B, 31D, 32B, 32D are set so as to occur in opposite directions.

  For example, when the tips of the inner piezoelectric actuators 31 and 32 are displaced upward (direction U shown in FIG. 3) when swinging around the Y axis, odd-numbered inner piezoelectric cantilevers 31A, 31C, 32A, 32C is displaced upward, and the even-numbered inner piezoelectric cantilevers 31B, 31D, 32B, 32D are displaced downward. In order to displace the tip portions of the inner piezoelectric actuators 31 and 32 in the downward direction, the odd-numbered inner piezoelectric cantilevers 31A, 31C, 32A and 32C are displaced in the downward direction, and the even-numbered inner piezoelectric cantilevers 31B, 31D and 32B, 32D is displaced upward.

  As a result, the odd-numbered inner piezoelectric cantilevers 31A, 31C, 32A, and 32C and the even-numbered inner piezoelectric cantilevers 31B, 31D, 32B, and 32D are bent and deformed in directions opposite to each other.

  When the reflecting portion 2 is swung around the X axis with respect to the outer support portion 6 by the outer piezoelectric actuators 51 and 52, the control unit 12 uses the outer piezoelectric actuator via the electrode pads 61 and 62 of the optical deflector 1. A drive voltage is applied to 51 and 52. Specifically, in one outer piezoelectric actuator 51, the control unit 12 drives the odd-numbered outer piezoelectric cantilevers 51A and 51C by applying the third voltage Vx1 to the corresponding electrode. At the same time, the control unit 12 drives the even-numbered outer piezoelectric cantilevers 51B and 51D by applying the fourth voltage Vx2 to the corresponding electrodes in the one outer piezoelectric actuator 51.

  As described above, the optical deflector 1 can drive the reflecting portion 2 at various angles by swinging the reflecting portion 2 around the Y axis and swinging the inner support portion 4 around the X axis. The light incident on the reflecting surface 2a can be emitted at various angles.

  The inner piezoelectric actuators 31 and 32 and the outer piezoelectric actuators 51 and 52 are equipped with piezoelectric cantilevers 32A to 32D and piezoelectric cantilevers 51A to 51D including a piezoelectric body as constituent elements. The piezoelectric actuators 51 and 52 serve as actuators that rotate the reflecting portion 2 about the Y axis and the X axis, and can also rotate the reflecting portion 2 about the Y axis and the X axis. It has a role as a movable connection part connected to the support part 6. Therefore, reducing the burden and improving the durability of the inner piezoelectric actuators 31 and 32 and the outer piezoelectric actuators 51 and 52 are important issues.

  FIG. 4 shows a scanning pattern in which the reflected light from the reflecting section 2 scans the irradiation area in front of the vehicle as spot light from the vehicle headlamp 10. In order to make the scanning pattern by the reflected light of the vehicle headlamp 10 easy to understand, a predetermined distance in front of the vehicle headlamp 10 is set to both an axis of α = 90 ° and an axis of β = 90 °. FIG. 5 shows a scanning pattern in which reflected light from the vehicle headlamp 10 is generated on the virtual screen, assuming a virtual screen standing vertically.

  FIG. 4A shows a reflected light scanning pattern in the forward pass period of the reflected light in the left-right direction scanning cycle, and FIG. 4B shows a reflected light scanning pattern in the returned pass period of the reflected light in the left-right direction scanning cycle. Yes.

  As shown in FIG. 4, the reflected light from the optical deflector 1 generates a light spot 80 on the virtual screen. The scanning pattern of FIG. 4 is shown as a scanning locus of the light spot 80 below the cut line 81, and the direction of the arrow in the scanning locus indicates the moving direction of the light spot 80.

  In FIG. 4, one cycle of the vertical scanning by the reflected light is such that the light spot 80 starts on the virtual screen from the lower folding point 82 or the upper folding point 83 to the next lower folding point 82 or the upper folding point 83. This is the period until returning. Further, one cycle of the horizontal scanning by reflected light is a period from when the light spot 80 departs from the left folding point 84 or the right folding point 85 to the same left folding point 84 or right folding point 85 on the virtual screen. It is a period.

  Therefore, the vertical scanning frequency of the reflected light is the reciprocal of the vertical scanning period. The horizontal scanning frequency of the reflected light is the reciprocal of the horizontal scanning period.

  As described above, in the vehicle headlamp 10, the main scanning direction and the sub-scanning direction of the reflected light are set to the vertical direction and the horizontal direction, respectively, so that the vertical scanning frequency of the reflected light is higher than the horizontal scanning frequency. Is set. In the forward period of the horizontal scanning period of the light spot 80, as shown in FIG. 4A, the horizontal irradiation part in the vertical scanning period of the light spot 80 moves by one pitch from the left to the right in the irradiation region. . In the return pass period, as shown in FIG. 4B, the left-right direction irradiation portion of the light spot 80 in the vertical scanning period moves by one pitch from right to left in the irradiation region.

  In FIG. 4, the cut line 81 is set to be horizontal, that is, set to an equal height regardless of the position in the left-right direction. Further, the laser light source 11 is always lit. The upper scanning turning point 83 in the vertical scanning period of the light spot 80 is aligned with the height of the light spot 80.

  In the optical deflector 1, the inner piezoelectric actuators 31 and 32 are used for the high-frequency reciprocal rotation of the reflection unit 2, and the outer piezoelectric actuators 51 and 52 are used for the low-frequency reciprocal rotation of the reflection unit 2.

  Therefore, in the conventional vehicle headlamp in which the main scanning direction and the sub-scanning direction of the reflected light are set to the left and right directions and the vertical direction, respectively, the light deflector 1 is in a horizontally long state as shown in FIG. Deployed in the casing of the lighting. That is, in the conventional vehicular headlamp, the optical deflector 1 is disposed so that the X axis and the Y axis orthogonal to each other are approximately in the horizontal direction and approximately in the vertical direction, respectively.

  On the other hand, in the vehicle headlamp 10 in which the main scanning direction and the sub-scanning direction of the reflected light are set to the vertical direction and the horizontal direction, respectively, the light deflector 1 is used for the vehicle in a vertically long state as shown in FIG. Deployed in the headlamp casing. That is, the optical deflector 1 is disposed such that the X axis and the Y axis orthogonal to each other are approximately in the vertical direction and in the horizontal direction, respectively.

  In both the conventional vehicle headlamp and the vehicle headlamp 10 according to the embodiment of the present invention, the inner piezoelectric actuators 31 and 32 oscillate the reflected light in the high-speed main scanning direction. However, in the conventional vehicular headlamp, the main scanning direction is the left-right direction in which the scanning angle range of the reflected light is large (50 ° in FIG. 2A), so that the inner piezoelectric actuators 31 and 32 rotate greatly. It is necessary to operate the range at a high speed, which increases the burden and decreases the durability.

  On the other hand, in the vehicle headlamp 10 according to the embodiment of the present invention, the main scanning direction is the vertical direction in which the scanning angle range of the reflected light is small, and the inner piezoelectric actuators 31 and 32 have a rotation range at a high speed. Although it is necessary to operate, the rotation range is greatly reduced (10 ° in FIG. 2B). As a result, the burden on the inner piezoelectric actuators 31 and 32 is greatly reduced and the durability is improved.

FIG. 5 shows the relationship between the light amount of the laser light source 11 and the vertical angle β of the reflected light in the vehicle headlamp 10. The light quantity of the laser light source 11 is switched in two steps according to β. That is, β _M is defined as an upper and lower angle β that switches the light amount of the laser light source 11 between large and small, and is small when β _L ≦ β <β _M , and is large when β _M ≦ β ≦ β _U. .

  Specifically, the control of the light amount of the laser light source 11 is performed by the control unit 12 controlling the energization amount of the laser light source 11. The laser light source 11 increases the light emission amount as the energization amount is increased. As a specific method of controlling the energization amount of the laser light source 11 by the control unit 12, (a) the laser light source 11 is continuously energized, and the continuous energization current value is increased or decreased. It is possible to supply a discontinuous energization pulse at a frequency and increase or decrease the pulse width (duty ratio) of the discontinuous energization pulse.

β _L ≦ β <β _M corresponds to the vertical angle β of the period during which the reflected light scans the vehicle vicinity portion of the irradiation region in the vertical scanning period, and β _M ≦ β ≦ β _U is the far portion Corresponds to the vertical angle β during the period of scanning. When the rotation of the reflecting portion 2 around the X axis by the outer piezoelectric actuators 51 and 52 is constant, the perspective scanning speed of the light spot 80 in the horizontal irradiation region becomes faster and larger in diameter at a point farther from the vehicle. Therefore, if the light quantity of the laser light source 11 is constant, the illuminance decreases as the point is farther in the horizontal irradiation region.

  In order to cope with this, it is conceivable to control the rotation speed of the reflecting portion 2 around the Y axis by the outer piezoelectric actuators 51 and 52 so that the lower the reflected light irradiates a distant portion. However, this makes it difficult to control the outer piezoelectric actuators 51 and 52 because the mechanical high-speed rotation of the reflector 2 must be controlled by increasing or decreasing the speed with a predetermined accuracy.

  On the other hand, in the vehicular headlamp 10, as shown in FIG. 5, by controlling the light amount of the laser light source 11, the light spot 80 is brightened during the period of irradiating the far part of the irradiation area. Thus, the illuminance of the irradiation area is made uniform. The light quantity control of the laser light source 11 is not mechanical control like the control of the outer piezoelectric actuators 51 and 52 but can be achieved only by controlling the energization amount to the laser light source 11, so that the control becomes simple. The accuracy of making the illuminance uniform in the irradiation area is improved.

  Furthermore, when the main scanning direction of the scanning light is the left-right direction as in the prior art, the time for which the scanning light stays in the distant portion is relatively long, so the time for maintaining the laser light source 11 at a large amount of light becomes long. . For this reason, the calorific value of the laser light source 11 increases, and the light emission efficiency of the laser light source 11 is reduced. In order to compensate for this, in the related art, when the energization amount of the laser light source 11 is increased, the heat generation amount of the laser light source 11 is further increased, and the light emission efficiency is likely to be reduced.

  On the other hand, in the vehicle headlamp 10, as a result of the main scanning direction of the scanning light being the vertical direction, a period in which the light amount of the laser light source 11 is increased as a period in which the reflected light irradiates a distant portion of the irradiation area; Since the switching frequency (frequency) of the period in which the reflected light is irradiated in the vicinity of the irradiation area and the period in which the light amount of the laser light source 11 is reduced increases, each period in which the laser light source 11 is continuously increased in light amount is shortened. The Thereby, since the heat generation of the laser light source 11 is reduced at an appropriate interval, a decrease in light emission efficiency is avoided.

  In FIG. 5, the light amount of the laser light source 11 is switched in two steps with respect to the change in the vertical angle β in the vertical scanning period. However, if the light amount of the laser light source 11 is increased as β increases, Three or more stages of switching and stepless control can be performed.

  FIG. 6 is an explanatory diagram of control for generating an arbitrary cut line 81 by ON (ON: ON) / OFF (OFF: OFF) control of the laser light source 11. In FIG. 6, it is assumed that the vehicle equipped with the vehicle headlamp 10 travels on the left lane of the road, and the lane on the right side of the travel lane is the lane on which the oncoming vehicle travels. The right side portion of the cut line 81 corresponds to an irradiation area on the oncoming vehicle side, and is lower than the eyes of the oncoming vehicle driver so that the oncoming driver is not dazzled by the reflected light of the vehicle headlamp 10. As shown in FIG.

  The trajectory of the light spot 80 in FIG. 6 is a trajectory when the laser light source 11 is always kept in an energized state for convenience of explaining the rotation of the reflecting unit 2. Actually, as will be described later, the laser light source 11 is turned off in a predetermined rotation angle range while rotating the reflection unit 2, so that the rotation movement of the reflection unit 2 is maintained, but the light spot A locus of 80 does not occur, and is an empty locus (an invisible locus).

  In FIG. 4 described above, the trajectory of the forward pass period and the trajectory of the return pass period of the light spot 80 in the horizontal scanning period are separately shown in (a) and (b), but in FIG. Show. Also in the case of FIG. 6, the traveling direction of the light spot 80 on the trajectory is reversed in the forward path period and the backward path period.

  The control unit 12 controls the inner piezoelectric actuators 31 and 32 so that the upper folding point 83 is above the cut line 81 and the upper folding point 83 is fixed regardless of the horizontal scanning position of the light spot 80. The rotation angle of the reflection part 2 around the Y axis is controlled via Generating an arbitrary cut line 81 by fixing the upper turning point of the rotation angle of the reflection unit 2 around the Y axis simplifies the control of the inner piezoelectric actuators 31 and 32 by the control unit 12.

  The controller 12 also keeps the laser light source 11 off during the period in which the light spot 80 scans above the cut line 81 if the laser light source 11 is on. Specifically, the control unit 12 detects the scanning position from the rotation angles of the reflection unit 2 around the X axis and the Y axis, and the scanning position where the reflected light crosses the cut line 81 from the bottom to the top is detected. Then, the laser light source 11 is switched from on to off, and when the scanning position where the reflected light exceeds the cut line 81 from top to bottom is detected, the laser light source 11 is switched from off to on.

  Thereby, although the reflection part 2 is controlled by the inner piezoelectric actuators 31 and 32 to direct the reflected light to the range above the cut line 81, the reflected light is not irradiated in the range above the cut line 81, The upper range is dark.

  Although FIG. 6 only shows that the laser light source 11 is turned on and off, the light amount control of the laser light source 11 of FIG. 4 can be performed in combination with the on / off control of FIG. In this case, since the laser light source 11 is cooled in the off period of each vertical scanning cycle, the light emission efficiency of the laser light source 11 is prevented from being lowered despite the increase in the light amount of the laser light source 11 with respect to the far part of the irradiation region. The

  Although the embodiment has been described as described above, the present invention is not limited to this. For example, the light source is not limited to the laser light source 11, and a light emitting diode (LED) can also be used. Moreover, a collimator lens can be arrange | positioned between a light source and a reflection part, and a HID (High Intensity Discharge lamp) or a halogen lamp can also be used as a light source.

  DESCRIPTION OF SYMBOLS 2 ... Reflection part, 10 ... Vehicle headlamp, 11 ... Laser light source (light source), 12 ... Control part (light quantity control part), 31, 32 ... Inner piezoelectric actuator, 51 , 52... Outer piezoelectric actuator, 80... Light spot, 81... Cut line, 82.

Claims (4)

A light source;
A reflection part that emits reflected light reflected from incident light from the light source to the front of the vehicle;
An actuator for rotating the reflecting portion around first and second axes so as to scan an irradiation area in front of the vehicle in the vertical and horizontal directions with the reflected light, respectively;
An automotive headlamp, comprising: an actuator control unit that controls the actuator so that a vertical scanning frequency of the reflected light is higher than a horizontal scanning frequency. The vehicle headlamp according to claim 1,
In the vertical scanning period with the reflected light, the light amount of the light source is controlled so that the light amount of the reflected light is increased in the scanning period in the upper range of the irradiation area compared to the scanning period in the lower range of the irradiation area. A vehicle headlamp comprising a light amount control unit. In the vehicle headlamp according to claim 2,
The actuator control unit controls the actuator so that the upper turning point of the vertical scanning is above the cut line of the irradiation area,
The vehicular headlamp, wherein the light amount control unit turns off the light source in a vertical scanning period in a range above the cut line of the irradiation area in each vertical scanning cycle. The vehicle headlamp according to claim 2 or 3,
The vehicle light amount control unit controls the light amount of the light source based on increase / decrease of a current value in continuous energization of the light source or increase / decrease of a pulse width of a discontinuous energization pulse of the light source. Lighting.

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