JP4238793B2 - Vehicle headlamp - Google Patents

Description

  The present invention provides an infrared illumination lamp for an infrared night-vision monitoring device that can obtain irradiation light using infrared light and visible light, functions as a passing beam when traveling in an urban area, and has an infrared camera or the like It also relates to a vehicle headlamp that also functions as a vehicle.

  FIG. 10 shows a conventional vehicle headlamp 100 of this type (see, for example, Patent Document 1). The vehicular headlamp 100 is configured such that a projection lens 52 is integrally assembled through a lens holder 51 in front of an ellipsoidal reflector 50 fitted with a light source, and the first focal point F1 of the reflector 50 is set. , The filament of the halogen bulb 53 which is a light source is located, and an infrared light transmission filter 54 constituting a light-shielding shade for light distribution control is located at the focal position of the projection lens 52 in the vicinity of the second focal point F2 of the reflector 50. Has been placed.

  The infrared light transmission filter 54 has a structure in which an infrared light transmission film 54a that is a shade body that reflects a visible light component and transmits an infrared light component is integrally attached to a circular transparent glass plate 54b. The infrared light transmission film 54a constitutes a light-shielding shade that shields visible light. In FIG. 10, reference numeral 55 denotes a lamp body, reference numeral 56 denotes a transparent front cover, and reference numeral S denotes a lamp chamber.

  According to the vehicle headlamp 100, the light emitted from the bulb 53 is reflected by the reflector 50 through the second focal point F2, and is parallel to the optical axis L by the projection lens 52, as indicated by arrows in FIG. Light is emitted forward.

  As shown in FIG. 11, the light distribution screen disposed in front of the automobile by the light emitted from the projection lens 52 has a predetermined visible line having a cut-off line CL corresponding to the upper edge portion 54 c of the infrared light transmission film. Since the light beam pattern P1 is formed and the infrared light transmission film 54a which is a light-shielding shade transmits the infrared light component, a predetermined infrared light beam pattern P2 including the visible light beam pattern P1 is invisible. Are also formed at the same time. In FIG. 11, symbol PH1 is a hot zone of the visible light beam pattern P1, and symbol PH2 is a hot zone of the infrared light beam pattern P2.

Here, the visible light beam pattern P1 functions as a lamp for illumination of a visible CCD camera in cooperation with other lamp units for forming a low beam. On the other hand, the invisible infrared light beam pattern P2 has the same irradiation area as the traveling beam pattern formed by the traveling beam forming lamp unit, and functions as an illumination lamp for an infrared light compatible CCD camera.
JP 2003-123520 A

  However, in the vehicle headlamp 100, the infrared light transmission filter 54 is disposed in the vicinity of the second focal point F2 of the reflector 50, so that the infrared light is affected by the thermal effect caused by the focusing of the light from the light source 53. There is a concern that the transmissive film 54a may be thermally deteriorated, and as a result, the durability of the infrared light transmissive filter is lowered.

  Therefore, the present invention can prevent thermal deterioration of the infrared light transmission filter by setting the infrared light transmission filter to a location that is not easily affected by the heat caused by the focusing of the light from the light source. Thus, an object of the present invention is to provide a vehicular headlamp with improved durability.

To achieve the above objects, an invention according to claim 1, wherein the first reflective surface having a first focus and the second focus, the first reflector comprises, around the first focal point of the first reflector A discharge lamp having a light emission center portion disposed therein, a shade disposed with a substantially central portion of the upper edge near the second focus position of the first reflector, and a lens focus near the second focus position. A vehicular headlamp including a projection lens disposed in front of the shade,
The first reflector is formed such that a front opening end thereof is substantially matched with an arrangement position of the shade, and a rear-side reflection surface having a smaller diameter than the first reflector, and a larger diameter than the first reflector. A second reflecting surface of the virtual reflecting surface formed as a free-form curved surface based on the rotating paraboloid or the rotating paraboloid surface. Is arranged so as to cover between the front opening end of the first reflector and the projection lens,
An outer opening formed between the second reflector and the projection lens is covered with an infrared light transmission filter ,
The second reflecting surface has a minimum focal length within the range of the opening width of the outer opening that can transmit the reflected emission image reflected at the reflection point at which the solid angle of the emission image of the reflection surface is the largest. It is formed as a front reflective surface of the virtual reflective surface formed with a virtual first focal point .

  For this reason, in the first aspect of the invention, the light from the light source is reflected by the first reflecting surface and the second reflecting surface. The light reflected by the first reflecting surface once converges on the second focal point, reaches the projection lens, is emitted as parallel visible light through the projection lens, and is reflected forward by the second reflecting surface. The emitted light becomes invisible infrared light through the infrared light transmission filter and is emitted forward.

  At this time, since the infrared light transmission filter is disposed at the outer opening formed between the second reflector and the projection lens, the infrared light transmission filter is disposed at a position farthest from the second focal position of the first reflector. Thus, it is possible to avoid as much as possible the thermal influence caused by the focusing of light from the light source in the vicinity of the first focal position of the first reflector.

In the first aspect of the present invention, the outer opening is formed so that the opening width between the second reflector and the projection lens has a minimum width through which the reflected emission image can be transmitted. In addition, the second reflecting surface is set to have the largest solid angle in terms of light distribution.

The invention according to claim 2 is the vehicle headlamp according to claim 1 ,
The infrared light transmission filter includes a front surface portion made of a prism having a function of diffusing incident light and a back surface portion made of an infrared light transmission film formed flat on the back surface of the prism. It is characterized by that.

For this reason, in the invention according to claim 2 , the incident condition of the light to the infrared light transmission filter is substantially perpendicular to the infrared light transmission film, and the infrared light component transmitted through the infrared light transmission film is The light is diffused by the prism and emitted as a wide outgoing light.

  According to the first aspect of the present invention, the infrared light transmission filter is disposed at a position farthest from the second focal position of the first reflector so as to avoid the influence of heat generation due to the light focusing of the light source as much as possible. Therefore, it is possible to prevent thermal deterioration of the infrared light transmission filter, thereby providing a vehicular headlamp including an infrared light transmission filter with improved durability.

According to the first aspect of the present invention, the opening width between the second reflector of the outer opening and the projection lens can transmit a reflected emission image having the maximum solid angle reflected by the second reflecting surface. because it is formed to have a minimum width, the outer-side opening can be reduced as much as possible the area of the infrared light transmitting filters covering, thereby together are possible control costs, the uniformity of the filter performance Can be easily kept.

  In addition, since the second reflecting surface is set to have the largest solid angle, a wide range that can be used as the reflecting surface can be secured, and a sufficient amount of infrared light can be secured, which is advantageous in terms of light distribution.

Further, according to the second aspect of the invention, the incident light conditions for the infrared light transmitting filter, since the substantially perpendicular to the infrared light transmitting film, in addition to the effect of the invention of claim 1 Symbol placement The incident efficiency of light with respect to the infrared light transmission filter can be maintained at a high level.

  In addition, the emitted light of the infrared component is diffused by the prism and can be emitted with an appropriate width capable of irradiating the object to be imaged, so that the imaging performance can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a vehicle headlamp 1 as one embodiment of the present invention. The vehicle headlamp 1 includes a first reflector 2 having a first reflecting surface 2a formed of a rotating paraboloid or a free curved surface based on the rotating paraboloid, and a first focal point of the first reflector 2. The light source 3 in which the light emission center portion 3a is disposed in the vicinity of the F1 position, the shade 4 in which the substantially central portion 4a of the upper end edge is disposed in the vicinity of the second focus F2 position of the first reflector 2, and the second focus F2. The projection lens 5 is generally configured to include a projection lens 5 disposed in front of the shade 4 with a lens focal point positioned in the vicinity of the position. In FIG. 1A, the symbol Z indicates the optical axis of the vehicle headlamp 1.

  At this time, the first reflector 2 is formed such that the front opening end 2b thereof is substantially matched with the position where the shade 4 is disposed, and the rear reflector 6 has a smaller diameter than the first reflector 2 (FIG. 1 (a ) And a virtual reflecting surface A formed as a free-form curved surface based on a rotating paraboloid or a rotating paraboloid having a front-side reflecting surface 7a having a diameter larger than that of the first reflector 2. Among them, the second reflector 7 having the front reflective surface as the second reflective surface 7a is disposed so as to cover between the front opening end 2b of the first reflector 2 and the projection lens 5, and the second An outer opening 8 formed between the reflector 7 and the projection lens 5 is covered with an infrared light transmission filter 9.

  More specifically, the light source 3 is constituted by a discharge lamp, and is supported and attached to a bulb insertion hole 10 formed in the rear top portion of the first reflector 2 with a socket portion 11. The shade 4 is formed so that its upper edge is similar to the cut-off line CL (see FIG. 2) of the visible light beam pattern P 1, and its lower edge leaves a sufficient space d between the first reflector 2 and the shade 4. The first reflector 2 is appropriately attached.

  The projection lens 5 is a plano-convex lens, and is attached to the second reflector 7 through a frame 12 as appropriate. As shown in FIG. 1B, the infrared light transmission filter 9 is attached over the entire circumference of the projection lens 5 so as to surround the projection lens 5. The infrared light transmission filter 9 includes a front surface portion 9a made of transparent glass and a back surface portion 9b made of an infrared light transmission film formed flat on the back surface of the transparent glass. As the infrared light transmitting film at this time, for example, a commercially available “03MCS cold mirror coating” (trade name, manufactured by Melles Griot Co., Ltd.) having the light transmitting characteristics shown in FIG. 3 is used.

  In the vehicle headlamp 1 configured as described above, the light of the light source 3 is reflected by the first reflecting surface 2a and the second reflecting surface 7a when the light source 3 is turned on. The light reflected by the first reflecting surface 2a once converges to the second focal point F2, reaches the projection lens 5, and is emitted forward as parallel visible light via the projection lens 5, thereby being second reflected. As shown in FIG. 1A, the reflected light L1 reflected by the surface 7a is emitted forward as infrared light L2 through the infrared light transmission filter 9, which is not visible.

  As shown in FIG. 2, a visible light beam pattern P1 and an infrared light beam pattern P2 are obtained simultaneously on the light distribution screen by these emitted lights. That is, the visible light beam pattern P1 is obtained by visible light and has a cut-off line CL, which is a suitable pattern for a passing beam. The infrared light beam pattern P2 is obtained by infrared light L2, and light distribution The hot zone PH2 has a hot zone PH2 at a position above the cut-off line CL of the visible light beam pattern P1 on the V-line on the screen and directly above the cut-off line CL of the visible light beam pattern P1. This is an elliptical pattern having an irradiation range of 2 mm. Since the hot zone PH2 of the infrared light beam pattern P2 is directly below the H line on the light distribution screen, the infrared light L2 reaches far and the imaging performance of the infrared light compatible camera is increased.

  In the vehicle headlamp 1, the infrared light transmission filter 9 is disposed in the outer opening 8 formed between the second reflector 7 and the projection lens 5, so that the second reflector 2 of the first reflector 2 is disposed. It will be arranged at a position farthest from the focal position F2, so that it is possible to avoid as much as possible the thermal influence caused by the focusing of the light of the light source 3 in the vicinity of the first focal position F1 of the first reflector 2. For this reason, thermal deterioration of the infrared light transmission filter 9 can be prevented in advance, and as a result, the durability of the vehicular headlamp 1 can be improved.

  Preferably, the second reflecting surface 7a is, as shown in FIG. 4, an outer opening 8 through which the reflected emission image 13 reflected by the reflection point 7b having the largest solid angle of the emission image of the reflection surface 7a can be transmitted. Is formed as a front reflection surface of the virtual reflection surface A formed with the virtual first focus f1 having the minimum focal length M within the aperture width H1.

  That is, when the reflected and emitted image 13 has a size H2, the virtual reflecting surface A has a virtual paraboloid or a rotating paraboloid having a virtual first focal point f1 having a minimum focal length M within a range of H1 ≧ H2. It is formed as a free-form surface based on a surface.

  In the present embodiment, the outer opening 8 has a size substantially equal to the size H2 of the reflected emission image 13 reflected by the reflection point 7b where the solid angle of the emission image of the second reflection surface 7a is the largest. 2 is formed with an opening width H1 between the reflector 7 and the projection lens 5, and the second reflection surface 7a is formed with a virtual first focus f1 having a focal length M. It is formed as a front reflective surface of A.

  In this embodiment, since the discharge lamp is applied as the light source 3, the reflected emission image 13 at that time is an arc image. However, the light source 3 can also be configured by an incandescent lamp, and the reflected emission image 13 at that time. Becomes a filament image.

  In this configuration, the reflected emission image reflected by the reflection point 7b where the opening width H1 between the second reflector 7 of the outer opening 8 and the projection lens 5 has the largest solid angle of the emission image of the second reflection surface is reflected. 13 is formed to have a size substantially equal to the size H2 of 13, that is, the minimum width (H1 ≧ H2) through which the reflected emission image 13 can be transmitted. Therefore, infrared light transmission covering the outer opening 8 is performed. The area of the filter 9 can be reduced as much as possible, thereby suppressing the cost and easily maintaining the uniformity of the filter performance.

  In addition, as shown in FIG. 4, the second reflecting surface 7a has a large use range D that can be used as a reflecting surface, so that the solid angle is set to be the largest in terms of light distribution, which is sufficient. Since the amount of infrared light can be secured, it is advantageous in terms of light distribution.

  FIG. 5 illustrates this light distribution advantage. The light emission center portion 3a of the light source 3 is set as the virtual first focal point f1 of the virtual reflecting surface A and the first focal point F1 of the first reflector 2. FIG. 5A shows the vehicle headlamp 1 according to the present invention in which the focal length of the virtual first focal point f1 is the distance M (minimum focal length within the range of H1 ≧ H2). FIG. 5B shows a vehicle headlamp 1a as a comparative product in which the focal length of the virtual first focal point f1 is the distance M1 (M1> M), and FIG. 5C shows the focal length of the virtual first focal point f1 as the distance M2. A vehicle headlamp 1b as a comparative product with (M2 <M) is shown. In FIG. 5, the symbol E indicates the light reachable range of the light source 3 with respect to the second reflector. In FIG. 5, the shade 4 and the infrared light transmission filter 9 are omitted.

  As can be seen from FIG. 5, the vehicle headlamp 1 has an appropriate range D that can be used as the reflecting surface of the second reflector, whereas the vehicle headlamp 1a has the use range described above. Not only the range becomes the small use range D1 (<D), but also the diameter of the second reflector (diameter φ) will be increased, and the vehicular headlamp 1b has a reduced diameter of the second reflector, The reflected light L1 is shielded by the frame 12 and is not emitted forward.

  More preferably, as shown in FIG. 6, the infrared light transmission filter 9 is formed flat on the front surface portion composed of the prism 9a that functions to diffuse incident light (reflected light L1 in FIG. 1) and on the back surface of the prism 9a. And a back surface portion made of the infrared light transmission film 9b. In the present embodiment, the prism 9a is formed to have a surface having a concavo-convex shape in which hook-shaped ridges are arranged in parallel.

  In this configuration, the light incident condition on the infrared light transmission filter 9 is substantially perpendicular to the infrared light transmission film 9b, and the infrared light component transmitted through the infrared light transmission film 9b is diffused by the prism 9a. As a result, the light is emitted forward as a wide outgoing light (infrared light L2 in FIG. 1).

  For this reason, in this embodiment, the incident efficiency of light with respect to the infrared light transmission filter 9 can be maintained at a high level, and the emitted light of the infrared component is diffused by the prism 9a to irradiate the subject to be imaged. Since it can radiate | emit with the appropriate width | variety possible, the improvement of imaging performance is achieved.

  FIG. 7 shows a vehicle headlamp 1A (FIG. 7A) and a vehicle headlamp 1B (FIG. 7A) as modified examples. The vehicle headlamps 1A and 1B are configured in the same manner as the vehicle headlamp 1 described above except that the arrangement of the infrared light transmission filter 9 is different.

  That is, the vehicular headlamp 1A is disposed at a position corresponding to a divided portion located above the projection lens 5 in the peripheral portion in which the infrared light transmission filter 9 encloses the projection lens 5 in the circumferential direction. It is configured by being. Similarly, the vehicular headlamp 1 </ b> B is provided at a position corresponding to a divided portion located below the projection lens 5, which is obtained by equally dividing the peripheral portion of the infrared light transmission filter 9 surrounding the projection lens 5 in the circumferential direction. It is constituted by being arranged.

  The vehicular headlamps 1A and 1B configured as described above have a small installation area of the infrared light transmission filter 9, so that not only cost reduction can be achieved, but also a characteristic of the discharge lamp 3 employed as a light source. Emission characteristics can be used.

  That is, as shown in FIG. 8, the discharge lamp 3 is attached to the bulb insertion hole 10 of the first reflector 2 with the light emission center portion 3a facing upward (see FIG. 1). Emits light up and down. At this time, the upward light emission L3 exhibits a blue-white emission color and increases the emission amount, and the downward emission L4 exhibits a yellow-white emission color and the emission amount decreases.

  The vehicle headlamp 1A can effectively use the upward light emission L3, and the light distribution pattern P2 of the infrared component emitted forward through the infrared light transmission filter 9 at the upper position is shown in FIG. As shown in FIG. 9, the pattern has a hot zone PH2 at the intersection of the V line and the H line on the light distribution screen. For this reason, the vehicle headlamp 1A has a large amount of emitted light from the light emission center portion 3a, and since there is a hot zone PH2 at the intersection of the V-line / H-line, the infrared component can reach far away. It has relatively high performance near infrared light irradiation.

  Further, the vehicle headlamp 1B can effectively use the downward light emission L4. The downward light emission L4 is usually not used as a visible light beam pattern because of its yellowish emission color, but is emitted forward through the infrared light transmission filter 9 at the lower position. For this reason, since the vehicle headlamp 1B forms an infrared light beam pattern using the downward light emission L4 that is not normally used as a visible light beam pattern, the visible light performance is not affected. High performance visible light irradiation performance.

  In addition, since the vehicle headlamps 1A and 1B utilize the upward light emission L3 and the downward light emission L4, respectively, the second reflector to be employed also has a semicircular cross-sectional shape with the lower open and the upper open, respectively. It can respond with the thing.

BRIEF DESCRIPTION OF THE DRAWINGS In the vehicle headlamp as one Embodiment of this invention, (a) is the longitudinal cross-sectional schematic diagram, (b) is the front view. It is explanatory drawing of the beam pattern of the vehicle headlamp of FIG. It is a graph which shows the light transmission characteristic of the infrared-light transmission film | membrane applied to the infrared-light transmission filter of the vehicle headlamp of FIG. It is a longitudinal cross-sectional schematic diagram explaining the characteristic of each part of the vehicle headlamp of FIG. FIG. 2 is a schematic longitudinal sectional view for explaining the light distribution advantage of the vehicle headlamp of FIG. 1, in which (a) shows a product of the present invention, (b) shows a comparative product, and (c) shows another comparative product. It is a perspective view of the infrared-light transmissive filter applied to the vehicle headlamp of FIG. (A) is a front view which shows the modification of the vehicle headlamp of FIG. 1, (b) is a front view which shows the other modification of the vehicle headlamp of FIG. It is a side view of the light source applied to the vehicle headlamp of FIG. It is an infrared-light beam pattern figure of the vehicle headlamp of Fig.7 (a). It is a longitudinal cross-sectional schematic diagram of the conventional vehicle headlamp. It is a beam pattern figure of the vehicle headlamp of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B Vehicle headlamp 2 1st reflector 2a 1st reflective surface 2b Front part opening end (of 1st reflector)
3 Light source (discharge lamp)
3a Light emission center part 4 Shade 4a Center part 5 Projection lens 6 Rear reflective surface 7 Second reflector 7a Second reflective surface (front reflective surface)
7b Reflection point 8 Outer opening 9 Infrared light transmission filter 9a Prism (surface part)
9b Infrared light transmission film (back side)
13 Reflected outgoing image A Virtual reflecting surface f1 Virtual first focus (of the virtual reflecting surface)
F1 first focus (of the first reflector)
F2 second focus (of the first reflector)
H1 opening width (outside opening)
H2 Size of reflected outgoing image L1 Reflected light L2 Infrared light M Focal length Z Optical axis

Claims (2)

A first reflecting surface having a first focus and the second focus, the first reflector comprises a discharge lamp luminescent center portion is disposed near the first focal point of the first reflector, said first reflector And a projection lens disposed in front of the shade with the lens focal point positioned in the vicinity of the second focal position. A vehicle headlamp,
The first reflector is formed such that a front opening end thereof is substantially matched with an arrangement position of the shade, and a rear-side reflection surface having a smaller diameter than the first reflector, and a larger diameter than the first reflector. A second reflecting surface of the virtual reflecting surface formed as a free-form curved surface based on the rotating paraboloid or the rotating paraboloid surface. Is arranged so as to cover between the front opening end of the first reflector and the projection lens,
An outer opening formed between the second reflector and the projection lens is covered with an infrared light transmission filter ,
The second reflecting surface has a minimum focal length within the range of the opening width of the outer opening that can transmit the reflected emission image reflected at the reflection point at which the solid angle of the emission image of the reflection surface is the largest. A vehicular headlamp, wherein the vehicular headlamp is formed as a front reflecting surface of the virtual reflecting surface formed with a virtual first focal point . The vehicle headlamp according to claim 1,
The infrared light transmission filter includes a front surface portion made of a prism having a function of diffusing incident light and a back surface portion made of an infrared light transmission film formed flat on the back surface of the prism. A vehicle headlamp characterized by that.

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