JP4884354B2 - Automotive headlamp - Google Patents

Description

  The present invention relates to an in-vehicle headlamp used as a headlamp for a vehicle, and more particularly to a technique for forming a headlamp using a surface light source.

  Where the lighting by the in-vehicle headlamp is different from general lighting, the driving direction in front of the driver to drive and sufficient brightness to clearly see pedestrians or traffic signs on the sidewalk are required, It has a unique light distribution characteristic that does not illuminate the driver who drives the oncoming vehicle, that is, the driver who drives the oncoming vehicle also requires darkness that is not dazzled.

  In the process of the transition of the light source used in conventional headlamps for vehicles, the filling gas of the light bulb (using tungsten filament) is devised, leading to the inclusion of halogen, and furthermore, a discharge lamp (HID lamp) that does not have a filament On the other hand, the light emission amount of the light source is increased (high luminous flux) to realize sufficient brightness, and on the other hand, the light source is set to 1 to realize darkness (specific light distribution). A number of improvements have been made to concentrate on the point (use of a point light source) and progress has been made. Of course, a lens or a reflector as a lamp has been developed for the same purpose.

  In the future, even if the light source of the in-vehicle headlamp is changed to a light source based on various light emission principles including a light emitting diode (LED), the in-vehicle headlamp will be required to have the above-mentioned specific light distribution, and it will always be a mechanism. Simple and inexpensive. For this reason, it is considered that the light source of the in-vehicle headlamp ultimately becomes one bright point light source.

  Recently, LED light flux has been increased and the light source of the in-vehicle headlamp is changing from a discharge lamp to a long-life LED. However, the LED as the current point light source is sufficient as the light source of the in-vehicle headlamp. The luminous flux is not high enough to secure the amount of light emission.

  Therefore, for the time being, a plurality of LEDs having a light emission amount that is insufficient as a point light source are arranged as a one-chip LED lighting unit in front of the vehicle and used as an in-vehicle headlamp, or a lamp-side lens or reflector is appropriately configured. Thus, a pseudo surface light source in which a plurality of LED chips are arranged must be used as the light source of the in-vehicle headlamp.

  Patent Document 1 and Patent Document 2 disclose a technique using a pseudo surface light source in which a plurality of LED chips are arranged. Each of these technologies is a configuration in which a plurality of small LED chips are arranged to form a surface light source in a pseudo manner. Since the surface light source has a complicated structure, it is inevitably expensive. Further, the amount of light emitted from each part of the light emitting surface varies depending on the arrangement density of the LED chips, and light emission spots occur.

  Patent Document 3, Patent Document 4 and Patent Document 5 disclose a technique in which an element of a surface light source is provided in an LED. In each of these technologies, a surface light source is configured by providing a light-shielding portion on a light-emitting window of a single LED chip, and each light-emitting unit configured by including an optical system in each LED has a light distribution of a headlamp. Take on. However, at present, since the amount of light emission per LED is small, sufficient brightness cannot be ensured without a plurality of light emitting units. Therefore, the vehicle-mounted headlamp has a complicated configuration and inevitably becomes expensive. In the technologies disclosed in Patent Document 3, Patent Document 4 and Patent Document 5, when the input power is increased to increase the individual light emission amount of the light source, the heat generation in the LED chip portion and the heat generation in the phosphor portion increase. However, there is a possibility that the service life may be lost at a high temperature due to overheating of both.

  Patent Document 6 and Patent Document 7 disclose a technique for improving the heat resistance of an LED for its own heat generation and the light resistance for its own light emission. In these technologies, the LED chip and the phosphor that generate heat are separated, and the LED and the phosphor are not overheated at the same time as in the technologies disclosed in Patent Document 1 to Patent Document 5 described above. There is little, and life can be extended. However, the technique disclosed in Patent Document 6 is a separate part in which the LED and the phosphor of the light source are completely separated, making the configuration complicated and expensive as a light source.

  In the technique disclosed in Patent Document 7, crystallized glass is used for a phosphor that outputs light facing an LED of a light source, and a high temperature is used without using a resin as a basic member for sealing the LED and the phosphor. It is configured to improve durability during use and to be irradiated with excitation light by a plurality of LEDs on a wide plate-like glass phosphor, but it is expensive as a light source because it uses a phosphor made of crystallized glass I can't deny it.

JP 2001-266620 A JP 2006-048934 A JP 2005-005193 A Japanese Patent Laid-Open No. 2005-093191 JP 2007-087946 A JP 2004-363060 A JP 2007-031196 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an inexpensive in-vehicle headlamp capable of illuminating the front with sufficient brightness and suitable light distribution. There is.

  In order to solve the above-described problem, an in-vehicle headlamp according to the present invention includes an excitation unit including a plurality of excitation elements that emit light or electrons, and light that is excited by light or electrons emitted from the excitation unit. A light-emitting unit made of a planar phosphor that emits light, a case that houses the excitation unit and the light-emitting unit, a light distribution adjusting unit that adjusts the light distribution of the planar light emitted by the light-emitting unit, and light emitted by the light-emitting unit The plurality of excitation elements of the excitation unit are arranged so as to be sparse or dense in order to adjust the brightness of the irradiation light irradiated to the front of the vehicle, or with the phosphor. It arrange | positions so that it may have a distance difference between.

  According to the in-vehicle headlamp according to the present invention, a plurality of excitation elements having small excitation energy are individually arranged behind one phosphor (wavelength conversion element) so as to be dense or dense, or The excitation unit is configured so that there is a difference in distance between them, and the phosphor emits light or electrons emitted from the excitation unit without any spots. In addition, adjust the light distribution and look at the driver, the opposite lane side illuminates the road surface without leaking light so that the driver does not directly reach the driver driving the oncoming vehicle, the sidewalk side is the road surface and sidewalk The upper side of the opposite lane is illuminated so that the side can be seen, and the driver is illuminated the farthest center far away from the center of the vehicle. It is possible .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing the structure of an in-vehicle headlamp according to Embodiment 1 of the present invention. FIG. 1 (a) is a top view of the right in-vehicle headlamp, and FIG. It is a side view.

  This in-vehicle headlamp is composed of a surface light source 1, a convex lens 2 as an optical member, a heat pipe 3, a control circuit 4, and a headlamp case 5 for housing them. A front lens 6 is formed on a part of the front side of the headlamp case 5 as shown in FIG.

The surface light source 1 generates planar light. As the surface light source 1, a light source represented by the following can be used, but a light source other than the following may be used.
(1) Type that converts electron energy into visible light ・ VFD (Vacuum Fluorescent Display)
・ CRT (Cathode Ray Tube)
・ FED (Field Emission Display)
(2) Type that converts ultraviolet light energy into visible light • HCFL (Hot Cathode Fluorescent Lamp)
・ CCFL (Cold Cathode Fluorescent Lamp)
・ LED (Light Emitting Diode)
(3) A type that converts the energy of blue light into yellow. LED (white light or near-white light (hereinafter simply referred to as “white light”) obtained by mixing the blue light of an LED with yellow light emitted by a phosphor) )

  Hereinafter, each light source will be briefly described. As shown in FIG. 2, in the VFD, thermoelectrons generated from a filament heated by energization are irradiated to the phosphor, and light is generated from the surface of the phosphor irradiated with the thermoelectrons. Similarly, in the CRT, as shown in FIG. 3, the phosphors are irradiated with thermionic electrons generated from the heated filament, and light is generated from the back surface of the surface irradiated with the thermoelectrons. As shown in FIG. 4, the FED emits light from the back surface of the surface irradiated with electrons by irradiating the phosphor with electrons generated from the protrusions of the electrodes.

  As shown in FIG. 5, the HCFL irradiates phosphors with ultraviolet light generated when the thermoelectrons generated from the filament collide with mercury, and generates light from the back surface of the surface irradiated with the ultraviolet light. . As shown in FIG. 6, the CCFL irradiates phosphors with ultraviolet light generated when electrons generated from electrodes collide with mercury, and generates light from the back surface of the surface irradiated with ultraviolet light.

  As shown in FIG. 7, the LED emits light from the back surface of the surface irradiated with ultraviolet light or blue light by irradiating the phosphor with ultraviolet light or blue light generated by the LED chip. There are the following two types of light sources that generate white light using LEDs. That is, one is to irradiate a phosphor (wavelength conversion element) emitting yellow light with blue light emitted from a blue light emitting LED, and mix the yellow light generated by the phosphor with the original blue light as white light. Output. Others irradiate phosphors that emit red, blue, and green light with ultraviolet light emitted by ultraviolet light-emitting LEDs, and mix the emission colors of the phosphors to output white light.

  FIG. 8 is a diagram showing a detailed structure of the surface light source 1 using LEDs, FIG. 8 (a) is a front view, and FIG. 8 (b) is a side view. The surface light source 1 has a planar shape in which a plurality of LED chips 11 as a plurality of excitation elements are arranged on a substrate 12, and a planar shape arranged at a predetermined distance from the excitation unit (a plurality of LED chips 11). On the light emitting section composed of the phosphor 13, the substrate 12 on which the plurality of LED chips 11 are arranged, the case 14 for housing the phosphor 13, and the back surface of the case 14 (the surface opposite to the surface to which the substrate 13 is attached). The provided heat dissipation part 15 is provided.

  Specifically, the plurality of LED chips 11 are sparse and dense on the substrate 12. Specifically, the upper side (B part) in the figure becomes “sparse” and the lower (A part) becomes “dense”. It is arranged to be. Further, as shown in FIG. 8A, a region 16 where no LED chip is mounted is provided on the right side of the A portion of the substrate 12, and this region 16 forms the shape of the light emitting surface of the phosphor 13. Then, it functions as a light distribution adjusting unit that adjusts the shape of the light / dark boundary portion of the irradiation light irradiated to the front of the vehicle, that is, the light distribution in the front left / right direction of the vehicle. As described above, the light distribution necessary for the in-vehicle headlamp can be realized with a simple configuration in which the region 16 where the LED chip is not mounted is provided on the substrate 12.

  Further, the end portion of the case 14 on the phosphor 13 side is bent so as to cover the periphery of the phosphor 13 to form a frame 14a, and an LED chip of the substrate 12 is mounted on a part of the A portion of the frame. It is wide so as to cover the region 16 that is not to be formed. An opening 17 on the light emitting surface is formed by the frame 14a. The widened portion of the frame 14a is a light shielding portion 14b that shields light from the phosphor 13, and this also functions as a light distribution adjusting portion that adjusts the light distribution in the front left and right directions of the vehicle. When the boundary between the light emitting portion of the phosphor 13 and the portion where the phosphor 13 does not emit light is unclear or the mechanical positional accuracy is not ensured, the light shielding portion 14b shields the light so that the boundary position and brightness are clarified. be able to. As described above, the light distribution necessary for the in-vehicle headlamp can be realized with a simple configuration in which a part of the frame 14a is widened to form the light shielding portion 14b.

  Further, the light shielding portion 14b is configured to have a predetermined thickness C in order to suppress the spectrum (prism effect) of the irradiation light due to the chromatic aberration of the convex lens 2. That is, in general, in consideration of the chromatic aberration of the convex lens 2, the phosphor 13 that emits blue having a shorter focal distance is brought closer to the convex lens 2, and the phosphor 13 that emits red having a longer focal distance is moved away from the convex lens 2. It is preferable to arrange in. If the convex lens 2 is glass, the difference in distance between them is 2-3% of the focal length. Therefore, the length C from the light emitting surface to the surface of the light shielding portion 14b on the convex lens 2 side is set to be substantially the same as the shape of the side of the light emitting surface of the phosphor 13 and the shape of the light shielding boundary line of the light shielding portion 14b. 3% or more of the focal length.

  Furthermore, in order to correct the curvature of the focal plane of the convex lens 2, if the outer side of the light emitting surface of the phosphor 13 is curved so as to be close to the convex lens 2, the focal plane is also affected by the irradiation light spreading to the left and right of the headlamp. The blur of the light / dark boundary line of the light distribution due to the influence of the curvature can be reduced.

  Similarly, as shown in FIG. 9, the thickness of the light shielding part 14b can be configured to be thin at the optical axis part and thick at the periphery. 9A is a top view and FIG. 9B is a side view. According to this configuration, it is possible to correct the influence of the curvature of the focal plane of the convex lens 2 where the light / dark boundary line of the light distribution becomes unclear.

  Furthermore, in order to reduce the diameter of the convex lens 2, as shown in FIG. 10, a convex lens 2a for reducing the diameter and a partition 2b for correcting curvature and chromatic aberration can be added in the vicinity of the surface light source 1. 10A is a top view and FIG. 10B is a side view. According to this configuration, the diameter of the convex lens 2 can be reduced, and the influence of the chromatic aberration of the convex lens 2 and the curvature of its focal plane can be corrected.

  The convex lens 2 and the convex lens 2a described above are made of resin or glass, and a convex lens having a flat surface on one side or a Fresnel lens can be used to reduce the thickness. Further, in order to illuminate the left and right directions widely while ensuring the upper and lower light distribution, the convex lens 2 can be formed in a shape other than a spherical surface, or a shape in which a portion through which light does not pass can be deleted.

  The heat dissipating unit 15 is composed of a heat sink having a plurality of fins, and releases heat generated by the plurality of LEDs 11. With this configuration, the temperature rise of the plurality of LEDs 11 can be suppressed, the deterioration of the plurality of LEDs 11 can be suppressed, and the life can be extended. In this case, for example, the fins of the heat dissipation unit 15 are shown in detail in the description of FIG. 13 so that the heat dissipation capacity varies depending on the density of the plurality of LED chips 11, and are not shown in the figure. However, the fins on the upper side (B portion) in the figure can be shortened to reduce the heat radiation capacity, and the fins can be lengthened toward the lower side (A part) to increase the heat radiation capacity. With this configuration, the portion where the amount of emitted light is large has a high density of exciting current and inevitably increases the amount of heat generation, but the heat dissipation capacity of the portion where the amount of heat generation is large increases, so that the temperature of the case 14 can be balanced. , Partial deterioration due to local overheating can be suppressed.

  The heat pipe 3 corresponds to the diffusion portion of the present invention. The surface light source 1 of the projector-type vehicle headlamp is disposed at a deep position near the engine, and an optical member such as a convex lens 2 occupies the space, and convection gas that circulates inside the vehicle headlamp. Since the flow is hindered, the heat generated by the surface light source 1 tends to be trapped inside the vehicle headlamp.

  Although it is possible to provide a fan inside the in-vehicle headlamp for forced air cooling, in order to avoid overheating of the surface light source 1, heat generated in the surface light source 1 is transmitted to the front lens of the in-vehicle headlamp through the heat pipe 3. The surface light source 1 is cooled by leading to 6 and waste heat in the vicinity of the front lens 6. According to this configuration, there is an advantage that there is no movable part and the structure is simplified.

  The front lens 6 side of the in-vehicle headlamp has a larger space than the surface light source 1 side stored in the back, so that gas easily flows. If heat is transferred to the space by the heat pipe 3, the interior of the in-vehicle headlamp is increased. Since the gas is heated and the front lens 6 is heated by the heated gas, there is also an effect of preventing snow from adhering to the front lens 6 of the in-vehicle headlamp.

  The control circuit 4 performs control for supplying appropriate excitation energy to the surface light source 1 to light it. Specifically, control is performed such that a predetermined voltage is applied to the plurality of LEDs 11 to flow current. The control circuit 4 is configured integrally with the headlamp case 5. This eliminates the need for the wiring on the vehicle side, improves the space efficiency on the vehicle side, and reduces parts. The control circuit 4 can be configured to have a function of performing control for reducing the supplied power when the surface light source 1 is overheated, control for reducing the supplied power while the vehicle is stopped, and the like.

  In the surface light source 1 configured as described above, the plurality of LED chips 11 generate blue light or ultraviolet light and diffuse it into the space formed between the plurality of LED chips 11 and the phosphor 13. The inside of the case 14 forming this space is a reflecting surface, and blue light or ultraviolet light emitted from each of the plurality of LED chips 11 is mixed, and a part of the light is reflected by the reflecting surface to phosphor. 13 is irradiated.

  The phosphor 13 generates white light when excited by receiving blue light or ultraviolet light from the plurality of LED chips 11. In this case, the light emission amount of the phosphor 13 is the largest in the A part corresponding to the part where the LED chips 11 are densely arranged, and gradually decreases as the part B is approached. The light generated by the phosphor 13 is emitted toward the convex lens 2 using the opening 17 where the phosphor 13 is exposed as a light emitting surface.

  The convex lens 2 corresponds to the optical member of the present invention, and projects light from the light emitting surface of the surface light source 1 onto the front road surface of the vehicle via the front lens 6. As a result, a real image of the surface light source is formed on the front road surface and functions as a projector-type vehicle headlamp. In this case, bright light emitted from part A of the surface light source 1 is projected on a far part (SA part) in front of the front of the vehicle, and relatively dark light emitted from part B of the surface light source 1 is projected on the vehicle. It is projected on a portion near the front front (SB portion). As a result, a light distribution which is indispensable as an in-vehicle headlamp and which illuminates the distant front and illuminates the vicinity relatively darkly is realized.

  Moreover, the shape of the light / dark boundary part of the irradiation light irradiated to the front of the vehicle, that is, the light distribution in the front left / right direction of the vehicle is adjusted by the light distribution adjusting unit. That is, the portion shielded by the light distribution adjusting portion is the right side of the far front portion (SA portion) of the front side of the vehicle, that is, the oncoming lane side, so that the oncoming lane side directly meets the driver driving the oncoming vehicle. Illuminate the road surface without leaking light so that light does not reach, the sidewalk side can also illuminate the upper side from the opposite lane side so that the state of the road surface and sidewalk side can be seen, and the center where the driver should watch The farthest can be illuminated the brightest.

  VFD, CRT and FED irradiate phosphors emitting light of red, blue and green with electrons emitted by an electron emitting element such as a filament or an electrode, and each phosphor obtains and emits energy of electrons. The emission colors are mixed and output as white light.

  FIG. 11 is a diagram showing a detailed structure of the surface light source 1 using a VFD. FIG. 11A is a front view and FIG. 11B is a side view. The surface light source 1 has a planar shape in which a plurality of filaments 18 as a plurality of excitation elements are arranged on the back side of the glass plate 19 and a predetermined distance from the excitation unit (plurality of filaments 18). Phosphor 13, a case 14 for housing the plurality of filaments 18 and phosphors 13, and a heat radiating portion 15 provided on the back surface of the case 14 (the surface opposite to the surface on which the phosphor 13 is attached). .

  Specifically, the plurality of filaments 18 are sparse on the back side of the glass plate 19. Specifically, the upper side (B part) in the figure becomes “sparse” and the lower side (A part) becomes “dense”. It is arranged to become. Moreover, as shown in FIG. 11A, a part of the right side of the A portion of the phosphor 13 (substantially the same shape as the opening section) is cut out, and this cut out region 16 is irradiated to the front of the vehicle. It functions as a light distribution adjusting unit that adjusts the shape of the light / dark boundary portion of the irradiated light, that is, the light distribution in the front left / right direction of the vehicle. Further, the end of the case 14 on the side of the glass plate 19 is bent so as to cover the periphery of the glass plate 19, and a frame 14a is formed. By this frame 14a, an opening 17 on the light emitting surface (substantially the same as phosphor). The same shape) is formed.

  The heat radiating part 15 is composed of a heat sink having a plurality of fins, and releases the heat generated by the phosphor 13. With this configuration, the temperature rise of the phosphor 13 can be suppressed, the deterioration of the phosphor 13 can be suppressed, and the life can be extended. Alternatively, the phosphor 13 can be directly attached to the heat radiating portion 15 so as to be the outer wall of the case 14 while making the heat radiating portion 15 a part of the anode electrode. In this case, the fins of the heat radiating section 15 are shown in detail in the description of FIG. 13, for example, so that the heat radiating capacity varies depending on the position of the phosphor 13, and are not shown in the figure. The fins on the upper side (B part) in the inside can be shortened to reduce the heat dissipation capacity, and the fins can be lengthened toward the lower side (A part) to increase the heat dissipation capacity. With this configuration, the portion where the amount of emitted light is large has a high density of exciting current and inevitably increases the amount of heat generation, but the heat dissipation capacity of the portion where the amount of heat generation is large increases, so that the temperature of the case 14 can be balanced. , Partial deterioration due to local overheating can be suppressed.

  In the surface light source 1 configured as described above, the plurality of filaments 18 generate heat when current is applied, and emit thermoelectrons when a constant high voltage is applied. Thermoelectrons emitted from each of the plurality of filaments 18 are applied to the phosphor 13. The phosphor 13 is made of a fluorescent material that emits red, blue, and green colors. The phosphors 13 are mixed with each other and emitted as white light when excited by thermal electrons from the filaments 18 colliding with each other. To do. In this case, the amount of light emitted from the phosphor 13 is the largest in the portion A corresponding to the portion where the filaments 18 are densely arranged, and gradually decreases as the portion B is approached. The light generated by the phosphor 13 is radiated toward the convex lens 2 from the opening 17 where the glass plate 18 is exposed. Hereinafter, similarly to the surface light source 1 using the above-described LED, the front road surface of the vehicle is irradiated with a light distribution that is indispensable as an in-vehicle headlamp.

  In the surface light source 1 using the VFD described above, the plurality of filaments 18 are arranged so that the B part becomes “sparse” and the “A” part becomes “dense”, but the plurality of filaments 18 are fixed. It can also arrange | position by space | interval, it can also comprise so that a low voltage may be applied to the filament of B part and the voltage applied may become high as it becomes A part. Alternatively, a plurality of filaments 18 to which a constant high voltage is applied are arranged at regular intervals, the distance between the filament 18 and the phosphor 13 in the B part is increased, and the distance is made closer to the A part. You can also. In these cases as well, the same operations and effects as in the case where the plurality of filaments 18 are densely arranged are produced.

  The HCFL and CCFL generate ultraviolet light by exciting electrons emitted by an electron-emitting device such as a filament or an electrode by colliding with an internal encapsulated gas, and the generated ultraviolet light is red, blue and green. The phosphors emitting the respective colors are irradiated with each other, and the respective emission colors emitted from the phosphors by obtaining energy of ultraviolet light are mixed and output as white light.

  FIG. 12 is a side view showing a detailed structure of the surface light source 1 using a barrier discharge type CCFL. The surface light source 1 includes a transparent electrode 20 attached to the front surface of the glass plate 19, a plate-like phosphor 13 attached to the back surface of the glass plate 19, and the glass plate 19, the transparent electrode 20 and the phosphor 13. An electrode 21 formed on a part of the case 14 to be stored and a heat radiating portion 15 attached to the electrode 21 are provided. The excitation part of the present invention is composed of a transparent electrode 20 and an electrode 21.

  The transparent electrode 20 and the electrode 21 are arranged such that the distance between them becomes wider on the upper side (B part) in the drawing and becomes narrower on the lower side (A part), forming a so-called wedge-shaped space. Has been. Further, in order to effectively irradiate the phosphor 13 with ultraviolet light generated by the collision of electrons, the surface 21a of the electrode 21 is a mirror surface. Furthermore, although illustration is omitted, as in the surface light source 1 using the VFD shown in FIG. 11A, a part of the right side of the A portion of the phosphor 13 is cut out, and this cut out region is , It functions as a light distribution adjusting unit that adjusts the shape of the light / dark boundary portion of the irradiation light irradiated to the front of the vehicle, that is, the light distribution in the front left / right direction of the vehicle. Moreover, the edge part by the side of the glass plate 19 of the case 14 is bent so that the periphery of the glass plate 19 may be covered, and the frame 14a is formed, and the opening part 17 of the light emission surface is formed by this frame 14a. .

  The heat radiating portion 15 is composed of a heat sink having a plurality of fins, and releases the heat generated by the electrode 21. With this configuration, the temperature rise of the electrode 21 can be suppressed, the deterioration of the electrode 21 can be suppressed, and the life can be extended. In this case, for example, the fins on the upper side (B part) in the figure are shortened to reduce the heat radiation capacity so that the fins of the heat radiation part 15 have different heat radiation capacity depending on the position of the phosphor 13. The fins can be lengthened and the heat dissipation capacity can be increased as (A part) is reached. With this configuration, the portion where the amount of emitted light is large has a high density of exciting current and inevitably increases the amount of heat generation, but the heat dissipation capacity of the portion where the amount of heat generation is large increases, so that the temperature of the case 14 can be balanced. , Partial deterioration due to local overheating can be suppressed.

  The electrode 21 emits electrons when a constant high frequency high voltage is applied between the electrode 21 and the transparent electrode 20. The emitted electrons collide with the sealed gas and are excited to generate ultraviolet light. The generated ultraviolet light is applied to the phosphor 13 and the phosphor 13 is excited to output white light. In this case, the light emission amount of the phosphor 13 is the largest in the A portion where the distance between the transparent electrode 20 and the electrode 21 is close, and gradually decreases as the B portion is approached. The light generated by the phosphor 13 is emitted toward the convex lens 2 with the opening 17 where the transparent electrode 20 on the glass plate 19 is exposed as a light emitting surface. Hereinafter, similarly to the surface light source 1 using the above-described LED, the front road surface of the vehicle is irradiated with a light distribution that is indispensable as an in-vehicle headlamp.

  In addition, when making a fluorescent substance light-emit by excitation by an electron, it can comprise so that light may be emitted from the back surface of an excitation surface similarly to the surface light source 1 using LED (CRT and FED are also the same), or VFD is used. Like the surface light source 1 used, it can be configured to emit light by reflecting in the electron irradiation direction.

  13A and 13B are diagrams showing a detailed structure of the surface light source 1 using the FED. FIG. 13A is a front view and FIG. 13B is a side view. The structure of the FED is not limited to the structure in which the phosphor is opposed to the electrode in parallel as shown in FIG. 4 as long as the structure emits white light by reflection. The surface light source 1 shown in FIG. 13 includes an electrode 22 as an excitation part having fine protrusions, a plate-like phosphor 13 arranged so as to have an inclination of 45 ° with respect to the electrode 22, and these electrodes. 22 and the case 14 for storing the phosphor 13, the heat dissipating portion 15 attached to one surface outside the case 14 (the surface opposite to the phosphor 13), and the glass plate 19 provided in the opening 17 of the case 14. I have.

  The distance from the electrode 21 to the phosphor 13 becomes closer to the lower side (A portion) in the upper side (B portion) in the figure. Further, as shown in FIG. 13 (a), a part of the right side of the A portion of the phosphor 13 is cut off, and the cut out region 16 has a shape of a light / dark boundary portion of irradiation light irradiated to the front of the vehicle. That is, it functions as a light distribution adjusting unit that adjusts the light distribution in the front left and right direction of the vehicle. Moreover, the edge part by the side of the glass plate 19 of the case 14 is bend | folded so that the periphery of the fluorescent substance 13 may be covered, and the frame 14a is formed, and a part of A part of the frame 14a is wide. An opening 17 on the light emitting surface is formed by the frame 14a. The wide part of the frame formed at the end of the case 14 is a light-shielding portion 14b that shields light from the phosphor 13, and this also adjusts the light distribution in the front left / right direction of the vehicle. It functions as a part.

  The heat radiating part 15 is composed of a heat sink having a plurality of fins, and releases the heat generated by the phosphor 13. With this configuration, the temperature rise of the phosphor 13 can be suppressed, the deterioration of the phosphor 13 can be suppressed, and the life can be extended. Alternatively, the phosphor 13 can be directly attached to the heat radiating portion 15 so as to be the outer wall of the case 14 while making the heat radiating portion 15 a part of the anode electrode. In this case, for example, the fins on the upper side (B part) in the figure are shortened to reduce the heat dissipation capacity of each fin of the heat dissipation part 15 so that the heat dissipation capacity varies depending on the position of the phosphor 13. The fins can be lengthened toward the side (A portion) to increase the heat dissipation capacity. With this configuration, the portion where the amount of emitted light is large has a high density of exciting current and inevitably increases the amount of heat generation, but the heat dissipation capacity of the portion where the amount of heat generation is large increases, so that the temperature of the case 14 can be balanced. , Partial deterioration due to local overheating can be suppressed.

  The electrode 22 emits electrons from the protrusion when a constant high voltage is applied. When the phosphor 13 is excited by the emitted electrons, white light is output. In this case, the light emission amount of the phosphor 13 is the largest in the A part where the distance between the electrode 22 and the phosphor 13 is close, and gradually decreases as the B part is approached. The light generated by the phosphor 13 is emitted toward the convex lens 2 from the opening 17 where the glass plate 19 is exposed. Hereinafter, similarly to the surface light source 1 using the above-described LED, the front road surface of the vehicle is irradiated with a light distribution that is indispensable as an in-vehicle headlamp.

  In addition, since the part where the electrode 22 and the phosphor 13 are close is located behind the opening 17 and is away from the opening 17, the problem of chromatic aberration that occurs when the convex lens 2 is used is solved. This increases the degree of freedom in designing the headlamp for in-vehicle use.

  As described above, the on-vehicle headlamp according to the first embodiment of the present invention is configured such that the light emitting part by the phosphor 13 and the excitation part by the LED or the electron emitting element are arranged separately. Therefore, it is possible to make it difficult for the heat generated by the two to be transmitted to each other, and it is possible to avoid the problem that they both affect each other and overheat and deteriorate.

  In addition, since the light emitting unit is composed of a surface light source having an area, the light emission amount per unit area of the phosphor 13 can be kept at an appropriate (low) value. As a result, it is not necessary to emit light excessively, so heat generation can be suppressed, deterioration of the phosphor such as a decrease in the luminous efficiency of the phosphor or a change in chromaticity of light emission is suppressed, and the life of the light emitting part is extended. Can do.

  For example, if a surface light source is formed by arranging bullet-shaped LEDs as disclosed in Patent Document 1, the light emitted from each LED has directivity, and the central axis of each LED is a spot. The brightness of the irradiated surface tends to be uneven. On the other hand, according to the in-vehicle headlamp according to the first embodiment of the present invention, the phosphor can appropriately irradiate the light emitted from the individual LEDs or the electrons emitted from the electron emitting element. From the pseudo surface light source in which the LEDs are arranged, it is possible to realize a surface light source that is free from unevenness in both the light emission amount and the light emission color, and it is possible to realize a good irradiation light of the vehicle headlamp.

  Further, for example, color spots of irradiated light due to chromatic aberration of convex lenses provided in individual LEDs as disclosed in Patent Literature 3, Patent Literature 4 and Patent Literature 5, excitation passing through phosphors provided in individual LEDs Since the light is mostly in the center (blue light that is transmitted is strong and blue is better if the excitation light is blue), and is less in the periphery (if the excitation light is blue, the yellow light that emits fluorescence is strong and yellow is better) Color spots are also present in the colors, and the color spots of the generated light-emitting surface are likely to appear, but the vehicle headlamp according to Embodiment 1 does not cause such a problem.

  In addition, it is difficult to realize bright light emission that illuminates a distant front, which is necessary as a vehicle-mounted headlamp, simply by arranging the LEDs with the same light emission amount, but the vehicle-mounted head according to Embodiment 1 According to the lamp, blue light or ultraviolet light emitted from individual LED chips or electrons emitted from the electron emitting element are in a diffused state, so if a phosphor is excited by arranging a plurality of light emitting sources or electron emitting sources close to each other, Adjacently irradiated light and electrons are mixed with each other to cause the phosphor to emit light, so that an irradiation surface with no spots can be formed.

  In addition, the light-emitting surface is divided into a plurality of parts, and the light distribution of the on-vehicle headlamp is “light distribution for driving”, “light distribution for highways”, “light distribution for passing” or “light distribution for cornering”. In this way, it may be configured to appropriately select or switch according to the state of the vehicle.

  Furthermore, in order to obtain the light intensity (unit cd) or illuminance (unit lx) required for a vehicle headlamp, when using an LED, the number of luminous flux (unit lm) per unit is small, so a plurality of lights are required. It is necessary to secure a sufficient luminous flux. For example, the luminous flux of a D2 type discharge lamp (35 W) is about 3000 lm, and assuming that half of the light emission amount is used as the light of the vehicle-mounted headlamp, a luminous flux of substantially 1500 lm is used as the vehicle-mounted headlamp. ing. In order to obtain the same brightness as that of the in-vehicle headlamp of the discharge lamp type by using LEDs, if the luminous flux generated by each LED is 75 lm, it is necessary to turn on 20 LEDs simultaneously. That is, even if it is a discharge lamp of a point light source, a light source using 20 LED chips, or a surface light source of a larger area, it has an equivalent performance as long as it has a luminous flux of substantially 1500 lm. The vehicle-mounted headlamp can be configured.

  Further, when the phosphor (wavelength conversion element) absorbs blue light or ultraviolet light and emits light of a different color (wavelength), a conversion loss occurs, and heat is generated by this loss. Therefore, when a large amount of light is emitted (wavelength conversion) in a small area, heat is concentrated on a small phosphor and overheats. This overheating causes stress to deteriorate the phosphor and shorten the lifetime.

  However, the area of the phosphor of the surface light source using the LED chip (the phosphor also exists in the corresponding part between the adjacent LED chips) is the phosphor (LED chip) housed in a small bullet-shaped LED. The light emission amount per unit area of the phosphor of the surface light source can be made lower than the light emission amount of the phosphor in the LED chip. In other words, if the surface light source is a single-surface phosphor, the load per unit area for converting the blue light or ultraviolet light of the phosphor into white light can be reduced. Can be reduced, and the lifetime of the phosphor can be extended.

Embodiment 2. FIG.
The in-vehicle headlamp according to Embodiment 2 of the present invention uses a concave mirror as an optical member instead of a convex lens.

  14A and 14B are diagrams showing the structure of an in-vehicle headlamp according to Embodiment 2 of the present invention. FIG. 14A is a top view of the right in-vehicle headlamp, and FIG. It is a side view. This in-vehicle headlamp includes a surface light source 1, a concave mirror 7 as an optical member, a heat pipe 3, a control circuit 4, and a headlamp case 5 that houses these. A front lens 6 is formed on a part of the front side of the headlamp case 5 as shown in FIG. Hereinafter, a description will be given focusing on the differences from the first embodiment.

  The concave mirror 7 corresponds to the optical member of the present invention, reflects light from the light emitting surface of the surface light source 1, and projects it onto the front road surface of the vehicle via the front lens 6. As a result, a real image of the surface light source is formed on the front road surface, and functions as a reflector (parabolic) type in-vehicle headlamp.

  The surface light source 1 is disposed in front of the concave mirror 7 and below the front lens 6 that forms a part of the headlamp case 5. In this reflector type in-vehicle headlamp, the surface light source 1 can be arranged below the front lens 6, and this arrangement generates convection in the gas inside the in-vehicle headlamp. The surface light source 1 can be cooled by the gas flow. In addition, the front lens 6 immediately above is heated by the heat transmitted by the convection rising airflow, and the effect of preventing snow from adhering to the front lens 6 is also achieved.

  In addition, cooling by the heat pipe 3 is also effective, and in an in-vehicle headlamp that is longer in the left-right direction than the depth in the front-rear direction, the surface light source 1 is cooled by carrying heat by laying the heat pipe 3 and heating the internal space. The efficiency and the heating efficiency of the front lens 6 can be increased at the same time.

It is a figure which shows the structure of the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of VFD as a light source which can be used with the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of CRT as a light source which can be used with the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of FED as a light source which can be used with the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of HCFL as a light source which can be used with the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of CCFL as a light source which can be used with the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of LED as a light source which can be used with the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the detailed structure of the surface light source using LED used in the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the structure which correct | amends the influence by the curvature of the chromatic aberration and focal plane of the convex lens used in the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the structure which correct | amends the influence by the curvature of the chromatic aberration and focal plane of the convex lens used in the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the detailed structure of the surface light source using VFD used in the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the detailed structure of the surface light source using the barrier discharge type CCFL used in the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the detailed structure of the surface light source using FED used in the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the vehicle-mounted headlamp which concerns on Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Surface light source, 2, 2a Convex lens (optical member), 2b Screen, 3 Heat pipe, 4 Control circuit, 5 Head lamp case, 6 Front lens, 7 Concave mirror (optical member), 11 LED chip (excitation part), 12 Board | substrate , 13 Phosphor (light emitting part), 14 case, 14a frame, 14b light shielding part (light distribution adjusting part), 15 heat radiating part, 16 region, 17 opening part, 18 filament (excitation part), 19 glass plate, 20 transparent electrode (Excitation part), 21 electrode (excitation part), 21a surface of electrode, 22 electrode (excitation part).

Claims (11)

An excitation unit having a plurality of excitation elements that emit light or electrons;
A light emitting part by a planar phosphor that emits light when excited by light or electrons emitted from the excitation part;
A case housing the excitation unit and the light emitting unit;
A light distribution adjusting unit for adjusting the light distribution of the planar light emitted from the light emitting unit;
An optical member that irradiates the front of the vehicle with the light emitted by the light emitting unit;
The plurality of excitation elements of the excitation unit are arranged sparsely or so as to have a difference in distance from the phosphor so as to adjust the brightness of the irradiation light applied to the front of the vehicle. Automotive headlamp. The in-vehicle headlamp according to claim 1, wherein a shape of a light / dark boundary portion of irradiation light irradiated to the front of the vehicle is formed by a shape of a phosphor functioning as a light distribution adjusting portion. The shape of the light / dark boundary part of the irradiation light irradiated to the front of the vehicle is formed by shielding a part of the light emitted from the phosphor by a light shielding part provided as a light distribution adjusting part. The in-vehicle headlamp described. The in-vehicle headlamp according to claim 1, wherein the case is provided with a heat radiating portion for releasing the generated heat. The in-vehicle unit according to claim 4, wherein the heat dissipating part is formed to have a different heat dissipating capacity in accordance with a density of a plurality of exciter elements in the exciter part or an arrangement having a distance difference from the phosphor. Headlamp. 2. The in-vehicle headlamp according to claim 1, wherein the optical member comprises a convex lens that projects the light emitting surface of the light emitting portion toward the front of the vehicle. The light blocking unit provided as the light distribution adjusting unit has a predetermined thickness in order to block a part of the planar light emitted by the phosphor and to suppress the spectrum of the irradiated light due to the chromatic aberration of the convex lens. The in-vehicle headlamp according to claim 6. The in-vehicle headlamp according to claim 1, further comprising a diffusion portion for diffusing heat generated by the case. 2. The in-vehicle headlamp according to claim 1, wherein the optical member is a concave mirror that projects the light emitting surface of the light emitting unit to the front of the vehicle. The case is disposed in front of a concave mirror and below a front lens that forms a part of a headlamp case that houses the case, the light distribution adjusting unit, and the optical member. Automotive headlamps. It has a control circuit that controls the lighting of the light emitting part,
11. The vehicle-mounted device according to claim 1, wherein the control circuit is formed integrally with a headlamp case that houses the case, the light distribution adjusting unit, and the optical member. head lamp.

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