Abstract:
An infrared radiating lamp which dilutes the red light emitted from the front lens of the lamp by causing a peripheral portion of the lens to emit white light or causing a small amount of white light to pass through a generally central portion of the lens so that the lamp will not be mistakenly recognized as a tail lamp or a stop lamp. The lamp includes a lamp body, a lens attached to a front opening portion of the lamp body and which cooperates with the lamp body to define a lamp chamber, a reflector provided at an inner side of the lamp body, a light source provided forward of the reflector, and an infrared transmitting film that reflects a visible light component and transmits an infrared component. A region having no infrared transmitting film is provided at an outer periphery of the infrared transmitting film. Light from the light source that does not pass through the infrared transmitting film is directed to the peripheral portion of the lens, so that the peripheral portion around the region in the lens that emits red light emits white light, thereby diluting the emission of red light. A similar effect can be obtained by forming a plurality of pores in the infrared transmitting film.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable  
         REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
         [0003]    Not applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    The present invention relates to an automotive infrared radiating lamp intended for installation on a motor vehicle and which illuminate an area forward of the vehicle with infrared light. More particularly, the invention relates to an automotive infrared radiating lamp for use together with a CCD camera having a sensitivity in a range that includes near infrared.  
           [0005]    In a conventional lamp of the same general type as that to which the invention pertains, a visible light source and a parabolic reflector may be disposed within a lamp chamber defined by a lamp body and a front lens. An infrared transmitting filter formed by an infrared transmitting film that reflects visible light and transmits infrared light and which covers the entire surface of a glass plate is disposed between a light source and the front lens so as to entirely cover the front opening portion of the lamp chamber. Thus, the entire light output of the light source radiated in the direction of the lens passes through the infrared transmitting fillet. When the light reflected by the reflector passes through the infrared transmitting film, the visible light component thereof is cut off so that primarily only the invisible infrared component is emitted through the front lens.  
           [0006]    An image of the infrared-irradiated area forward of the vehicle is sensed by a CCD camera which is mounted at a forward position on the motor vehicle and which has a sensitivity covering the near-infrared range. The image is processed by an image processing device, and the result displayed on a monitor screen in the passenger compartment of the vehicle. Using this system, the driver can recognize on the monitor screen the presence of persons, lane markings, obstacles, etc., even at considerable distances forward of the vehicle.  
           [0007]    However, the infrared transmitting filter (infrared transmitting film) is not able to completely cut off long-wavelength visible light at wavelengths of about 700 to 800 nm (red light component). Therefore, together with infrared light, a portion of the visible light from the light source (red light component) is transmitted through the infrared transmitting filter and emitted through the front lens together with infrared light, so that the front lens emits red light (the lamp glows red). Hence, there is a danger of the driver of an oncoming vehicle or a pedestrian falsely recognizing a lighted infrared radiating lamp mounted at a front position of a motor vehicle as a tail lamp or a stop lamp, which gives rise to a safety problem.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    The present inventor conceived that if a portion of the light from the light source is allowed to pass though to a peripheral portion of the front lens without passing through the infrared transmitting filter so as to illuminate the peripheral portions of the red-light-emitting front lens with white light, the red light emission would become less conspicuous. Experiments have concluded that this concept is indeed very effective. The inventor has proposed the present invention based on this concept.  
           [0009]    The invention has been accomplished based on the foregoing problems of the conventional art and the inventor&#39;s conception. It is an object of the invention to provide an infrared radiating lamp in which the emission of red light from the front lens is diluted by white light emitted from a peripheral portion of the lens or by a small amount of white light emitted from approximately a central portion of the lens, thereby preventing the lit lamp from being falsely recognized as a tail lamp, a stop lamp, or the like.  
           [0010]    In order to achieve the foregoing and other objects of the invention, an infrared radiating lamp in accordance with comprises a container-like lamp body, a lens attached to a front opening portion of the lamp body which cooperates with the lamp body to define a lamp chamber; a reflector provided at an inner side of the lamp body, a light source provided forward of the reflector, and an infrared transmitting film disposed between the light source and the lens, wherein a region having no infrared transmitting film is provided at an outer periphery of the infrared transmitting film and/or within the infrared transmitting film.  
           [0011]    In operation, when light emitted from the light source and reflected from the reflector passes through the infrared transmitting film provided forward of the reflector, a visible light component is cut off so that light formed mainly by an invisible infrared component passes through, the lens. However, the outgoing light from the lens still contains a visible light component (red light component) that cannot be eliminated by the infrared transmitting film. Therefore, when the lamp is illuminated, the lens emits some amount of red light. However, by providing the region having no infrared transmitting film at the outer periphery of the infrared transmitting film, light from the light source that does not pass through the infrared transmitting film passes through a peripheral portion of the lens. Therefore, the peripheral portion of the lens emits white light, which serves to dilute the red color of the light emitted from the lens. Furthermore, in the case where a region having no infrared transmitting film is provided within the infrared transmitting film, light from the light source that does not pass through the infrared transmitting film passes though an approximately central portion of the lens in a small amount, thereby serving to dilute the red color of light emitted from the lens. That is, although the quantity of red light emitted from the lens is not substantially different from the quantity of red light emitted in the conventional construction in which all the light emitted from the light source toward the lens passes through the infrared transmitting film, the lamp of the invention dilutes the red light with white light emitted from around the periphery around the red light-emitting region in the lens or by a small amount of white light passing through an approximately central portion of the lens.  
           [0012]    As for the basic construction of the infrared radiating lamp, various types can be employed, including a reflection-type illumination optical system wherein light from the light source is reflected by a parabolic reflector to form substantially parallel rays and a desired distribution of light is achieved with light distribution control steps formed on the front lens, a type which achieves the desired distribution of light using a reflector that has a plurality of contiguous divided reflection surfaces for light distribution control, and a type constructed with a projection-type illumination optical system that reflects light from the light source with an ellipsoidal reflector and then produces substantially parallel rays with a projection lens. The invention is applicable to any of these forms.  
           [0013]    Further in accordance with the invention, a transparent member may be provided between the reflector and the lens, the transparent member being provided with the infrared transmitting film.  
           [0014]    If in a simple construction using an infrared transmitting filter (a transparent member with an infrared transmitting film) the visible light cutting performance of the infrared transmitting filter (infrared transmitting film), for example, deteriorates due to high temperature heating, it is appropriate to replace only the infrared transmitting filter without replacing major component parts of the lamp.  
           [0015]    Moreover, in accordance with the invention, the lens may be provided with the infrared transmitting film. In such a case, since the infrared transmitting film is formed directly on the lens, there is no need for a separate transparent member for supporting the infrared transmitting film, as a result of which the lamp structure is correspondingly simple. Furthermore, retention of heat within the lamp chamber is less likely, and thermal deterioration of the infrared transmitting film is reduced in comparison with a construction in which an infrared transmitting filter (a transparent member having an infrared transmitting film) is employed. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a longitudinal sectional view of an infrared radiating lamp in accordance with a first embodiment of the invention.  
         [0017]    [0017]FIG. 2 is a rear side elevation of an infrared transmitting filters, which is a portion of the lamp of FIG. 1.  
         [0018]    [0018]FIG. 3 is a longitudinal sectional view of an infrared radiating lamp in accordance with a second embodiment of the invention.  
         [0019]    [0019]FIG. 4 is a longitudinal sectional view of an infrared radiating lamp in accordance with a third embodiment of the invention.  
         [0020]    [0020]FIG. 5 is a longitudinal sectional view of an infrared radiating lamp in accordance with a fourth embodiment of the invention.  
         [0021]    [0021]FIG. 6 is a perspective view of portions of the infrared radiating lamp of the fifth embodiment of the invention.  
         [0022]    [0022]FIG. 7 is a longitudinal sectional view of an infrared radiating lamp in accordance with a sixth embodiment of the invention.  
         [0023]    [0023]FIG. 8 is a longitudinal sectional view of an infrared radiating lamp.  
         [0024]    [0024]FIG. 9 is an exploded perspective view of the lamp. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    The invention will be described with reference to preferred embodiments thereof.  
         [0026]    [0026]FIGS. 1 and 2 illustrate an embodiment of an infrared radiating lamp that is suitably applicable to a nighttime forward view detection system, and that is used together with an infrared CCD camera, which is mounted in, for example, at an upper position in the passenger compartment of the vehicle, for sensing an image of the field of view forward of the vehicle. FIG. 1 is a longitudinal sectional view of the infrared radiating lamp in accordance with the first embodiment of the invention. FIG. 2 shows a rear side elevation of an infrared transmitting filter. which is a portion of the lamp.  
         [0027]    The nighttime forward view detection system includes as primary components an infrared radiating lamp  10 A mounted at a front position on the vehicle for emitting infrared light forward of the vehicle, an infrared CCD camera (not shown) mounted, for example, at an upper position in the passenger compartment of the vehicle for sensing an image of the field of view forward of the vehicle, an image processing-analyzing device for analyzing the image sensed by the CCD camera, and a head-up display (HUD).  
         [0028]    Images of otherwise invisible distant pedestrians, obstacles, lane markings and the like sensed by the CCD camera are applied to the image processing-analyzing device. Edge processing and pattern recognition of the images therein allows easy recognition of a pedestrian, obstacle, lane marking, etc. The images of a pedestrian, obstacles, lane markings, etc., are displayed to the driver via the head-up display (HUD), and certain characteristics of objects in the road (pedestrian, obstacle, lane markings, etc) are determined by shape recognition, and is indicated to the driver via voice.  
         [0029]    As shown in FIG. 1, the infrared radiating lamp  10 A includes a synthetic resin lamp body  12 , a front lens  14  attached to a front opening portion of the lamp body  12  and which defines a lamp chamber S in cooperation with the lamp body  12 , a parabolic reflector  16  formed together with an inner peripheral surface of the lamp body  12 , a halogen bulb  18  forming a light source and which is inserted into a bulb mounting hole  12   a  provided in a rear vertex portion of the lamp body  12 , and an infrared transmitting filter  20  extending transversely forward of the reflector  16 . Light distribution control cylindrical steps  15  that distribute light in a diverging manner in a predetermined direction are provided on the front lens  14 .  
         [0030]    As shown in FIG. 2. the infrared transmitting filter  20  includes an infrared transmitting film  22  formed on a surface of a transparent glass plate  21 . A peripheral portion of the infrared transmitting filter  20  (glass plate  21 ) is provided with a ring-shaped region  24 A having no infrared transmitting film. The ring-shaped region  24 A has a predetermined width. That is, the infrared transmitting film  22  is formed on the rear surface of the glass plate  21 , except for a peripheral region of predetermined width.  
         [0031]    As shown in FIG. 1, the peripheral portion of the infrared transmitting filter  20  is engaged with a groove  13  formed in an engagement portion between the lamp body  12  and the front lens  14 , and is thus positioned and fixed. That is, the infrared transmitting filter  20  can be fixed in a sandwiched manner simultaneously with the attachment of the front lens  14  to the lamp body  12 . This is convenient for the replacement of the infrared transmitting filter  20 .  
         [0032]    When the lamp is turned on, light from the light source which is reflected by the reflector  16  passes through the infrared transmitting filter  20  and the infrared transmitting film  22  thereof, as indicated by reference character L 1  in FIG. 1, whereby a visible light component is cut. Therefore, light composed primarily of an invisible infrared component passes through the front lens  14 . However, the outgoing light from the front lens  14  contains a visible light component (red light component) that remains despite the action of the infrared transmitting film  22 . Therefore, when the lamp is on, the front lens  14  emits some amount of red light. However, light from the light source that does not pass through the infrared transmitting film  22  is directed to a peripheral portion of the front lens  14  via the region  24 A having no infrared transmitting film, as indicated by reference character L 1 ′ in FIG. 1. Therefore, the peripheral portion  14   a  of the front lens  14  emits white light, thus serving to dilute the red color of light emission from the front lens  14 . That is, although the quantity of red light emission from the front lens  14  is substantially no different from the quantity of red light emitted in the conventional construction in which the entire light output from the light source in the direction of the front lens  14  passes through the infrared transmitting film  22 , in this embodiment the red color is significantly diluted by the white light emitted from the peripheral portion  14   a  around a red light-emitting region of the front lens  14 .  
         [0033]    [0033]FIG. 3 is a longitudinal sectional view of an infrared radiating lamp constructed in accordance with a second embodiment of the invention.  
         [0034]    In the foregoing first embodiment, the infrared transmitting filter  20  is mounted in the front opening portion of the lamp body  12  so as to close the lamp chamber S, and the infrared transmitting film  22  is formed thereon, leaving a peripheral portion of the glass plate  21  with no infrared transmitting film mounted thereon. However, in the infrared radiating lamp  10 B of the second embodiment, an infrared transmitting filter  20 A, composed of an infrared transmitting film  22  formed over the entire surface of a rear side of a glass plate  21 , is disposed so as to form a predetermined gap (region  24 B having no infrared transmitting film) between the lamp chamber S and the inner peripheral surface thereof. That is, engagement protrusions  23  are provided at a plurality of positions along the circumference of the infrared transmitting filter  20 A. The engagement protrusions  23  of the infrared transmitting filter  20 A are engaged in a groove  13  formed in an engagement portion between the lamp body  12  and the front lens  14 , thereby positioning and fixing the infrared transmitting filter  20 A in the lamp chamber S.  
         [0035]    When the lamp is turned on, light from the light source reflected from the reflector  16  passes through the infrared transmitting filter  20 A including the infrared transmitting film  22 , as indicated by reference character L 2  in FIG. 2, whereby the visible light component is substantially cut off. Therefore, light composed mainly of an invisible infrared component is irradiated through the front lens  14 . However, the outgoing light from the front lens  14  still contains some visible light component (red light component) that is not cut by the infrared transmitting film  22 . Therefore when the lamp is on, the front lens  14  emits some amount of red light. However, light that does not pass through the infrared transmitting film  22  is directed to a peripheral portion of the front lens  14  via the gap (the region  24 B having no infrared transmitting film), as indicated by reference character L 2 ′ in FIG. 2. Therefore, the peripheral portion  14   a  of the front lens  14  emits white light, thus diluting the red color of the light emitted from the front lens  14  and making the red color less conspicuous.  
         [0036]    The forward and rearward lamp chambers S separated by the infrared transmitting filter  20 A communicate with each other via gaps between the lamp chamber inner peripheral wall surfaces and a peripheral portion of the infrared transmitting filter  20 A. Therefore, air convection occurs between the forward and rearward chambers via the gaps, thus mitigating the retention of heat within the lamp chamber S.  
         [0037]    [0037]FIG. 4 is a longitudinal sectional view of an infrared radiating lamp constructed in accordance with a third embodiment of the invention.  
         [0038]    The infrared radiating lamp  10 C of the third embodiment employs a reflection-type illumination optical system in which a reflector  16 A has a plurality of continuous divided reflecting surfaces  17  for light distribution control, and a predetermined distribution of light is achieved by diffused reflected light from the divided reflecting surfaces  17 . A front lens  14  has no light distribution control steps  15  as in the case of first embodiment, but has a simple transmission surface.  
         [0039]    An infrared transmitting, filter  20  is formed directly on the rear surface of the front lens  14 A corresponding to the design surface thereof. A band-like region  24 C having no infrared transmitting film is provided on an inner surface of a side wall of the front lens  14 A, that is, a peripheral portion of the front lens  14 A.  
         [0040]    When the lamp is turned on, light from the light source reflected by the reflector  16 A passes through the infrared transmitting film  22 , as indicated by reference character L 3  in FIG. 4, whereby most of the visible light component is cut off. Therefore, light composed mainly of an invisible infrared component is emitted through the front lens  14 . However, the outgoing light from the front lens  14 A still contains a visible light component (red light component) that is not cut off by the infrared transmitting film. Therefore, when the lamp is on, the front lens  14  emits some amount of red light. However, light from the light source that does not pass through the infrared transmitting film  22  is directed to a peripheral portion of the front lens  14 A via the region  24 C having no infrared transmitting film, as indicated by reference character L 3 ′ in FIG. 4. Therefore, the peripheral portion  14   a  of the front lens  14 A emits white light, thus diluting the red color of light emission from the front lens  14  and making the red color less conspicuous.  
         [0041]    [0041]FIG. 5 is a longitudinal sectional view of an infrared radiating lamp constructed in accordance with a fourth embodiment of the invention.  
         [0042]    The foregoing first to third embodiments employ a reflection-type illumination optical system in which light from the light source is reflected by the reflector  16  so as to form substantially parallel rays, and the light rays are distributed in a diffused fashion by the light distribution control steps of the front lens  14 , or in which light from the light source is distributed in a diffused reflected manner by the reflector  16 A that has a plurality of continuous divided reflecting surfaces  17 . In contrast, the infrared radiating lamp  10 D in the fourth embodiment employs a projection-type illumination optical system in which light from the light source is reflected by an ellipsoidal reflector  16 B. and the reflected light is projection-distributed in the form of a substantially parallel beam by a projection lens  40 .  
         [0043]    A halogen bulb  18  is mounted so that the filament of the bulb  18  is positioned at a first focal point f 1  of the metallic ellipsoidal reflector  16 B, which forms a lamp body  12 . metallic cylindrical lens holder  30 , which forms the lamp body  12 , is fixed to tie reflector  16 B. A front opening portion of the lens holder  30  securely retains the projection lens  40  via an annular lens retainer frame  36  that has an “L” shape in cross section. Reference numeral  32  indicates a stepped portion that extends along an inner peripheral portion of the front opening portion of the lens holder  30  which is used to retain a flange portion  41  of the lens  40 . Light from the light source reflected by the reflector  16 B is converged at a second focal point f 2  of the reflector  16 B, and then is formed into a substantially light beam parallel to the optical axis of the reflector  16 B, as indicated by reference character L 4 , by the projection lens  40  disposed forward of the reflector  16 B. Thus, a substantially parallel beam is projected and distributed forward.  
         [0044]    A ring-shaped stepped portion  32 A for retaining a filter is formed in an inner peripheral portion of the lens retraining stepped portion  32  formed in the front opening portion of the lens holder  30 . An infrared transmitting filter  20 B received by the stepped portion  32 A is fixed and retained, together with the projection lens  40 , to the front opening portion of the lens holder  30  by the lens retainer frame  36 . Reference numeral  26  indicates a rubber member that extends along the peripheral portion of the infrared transmitting filter  20 B. The infrared transmitting filter  20 B and the projection lens  40  are spaced from each other by a distance corresponding to the thickness of the rubber member  26 .  
         [0045]    Similarly to the infrared transmitting filter  20  described above in conjunction with the first embodiment, the infrared transmitting filter  20 B has a structure in which an infrared transmitting film  22  is formed over a rear surface of a transparent glass plate  21  except for a peripheral portion of the rear surface, and a ring-shaped region  24 D having no infrared transmitting film is present in a peripheral portion of the infrared transmitting filter  20 B (glass plate  21 ). The ring-shaped region  24 D has a predetermined width.  
         [0046]    When the lamp is turned on, light from the light source reflected by the reflector  16 B passes through the infrared transmitting filter  20 B (the infrared transmitting film  22  thereof), as indicated by reference character L 4  in FIG. 5, whereby the visible light component is mainly cut off. Therefore, light composed primarily of an invisible infrared component is emitted from the projection lens  40 . However, the outgoing light from the projection lens  40  still contains a visible light component (red light component) that is not cut by the infrared transmitting film. Therefore, when the lamp is on, the projection lens  40  emits some amount of red light. However, light from the light source that does not pass through the infrared transmitting film  22  is directed to a peripheral portion of the projection lens  40  via the region  24 D having no infrared transmitting film, as indicated by reference character L 4 ′ in FIG. 5. Therefore, the peripheral portion  40   a  of the projection lens  40  emits white light, thus diluting the red color of light emitted from the projection lens  40  and making the red color less conspicuous.  
         [0047]    The infrared transmitting filter  20 B is disposed at a position sufficiently remote from the second focal point f 2 , at which high temperature occurs due to the convergence of light, that the possibility of thermal deterioration of the infrared transmitting film  22  is significantly reduced.  
         [0048]    [0048]FIG. 6 is a perspective view of portions of the infrared radiating lamp of the fifth embodiment of the invention.  
         [0049]    In the previously described fourth embodiment (see FIG. 5), the infrared transmitting filter  20 B having in a peripheral portion thereof the region  24 D having no infrared transmitting film is disposed so as to close the lamp chamber S 1 , that is, the infrared transmitting filter  20 B is disposed so that the peripheral portion of the filter contacts an inner peripheral surface of the lens holder  30 . In the infrared radiating lamp  10 E in the fifth embodiment, however, an infrared transmitting filter  20 C in which an infrared transmitting film  22  is formed over the entire rear surface of a glass plate  21  is disposed so that a peripheral portion of the filter is spaced slightly apart from the inner peripheral surface of the lens holder  30 . Thus, a region  24 E having no infrared transmitting film is provided around the periphery of the infrared transmitting filter  20 C.  
         [0050]    That is, filter-retaining inward protrusions  32 B with stepped portions are formed at three equidistant sites along the circumference of a lens-retaining stepped portion  32  formed in a front opening portion of the lens holder  30 . When the infrared transmitting filter  20 C is received by the inward protrusions  32 B, a gap (a region  24 E having no infrared transmitting film) is formed around the periphery of the infrared transmitting filter  20 C. As in the fourth embodiment, the infrared transmitting filter  20 C and the projection lens  40  are together fixed and mounted to the front opening portion of the lens holder  30  via the lens retainer frame  36 . Reference numeral  27  indicates rubber members provided on a peripheral portion of the infrared transmitting filter  20 B corresponding to the inward protrusions  32 B. Therefore, the infrared transmitting filter  20 C and the projection lens  40  are spaced apart from each other by a distance corresponding to the thickness of the rubber members  27 .  
         [0051]    When the lamp is turned on, light from the light source reflected by the reflector  16 B passes through the infrared transmitting filter  20 C (the infrared transmitting film  22  thereof), whereby a visible light component is cut. Therefore, light composed mainly of an invisible infrared component is emitted from the projection lens  40 . However, the outgoing light from the projection lens  40  still contains a visible light component (red light component) that is not cut by the infrared transmitting film. Therefore, when the lamp is on, the projection lens  40  emits some amount of red light. However, light from the light source that does not pass through the infrared transmitting film  22  is directed to a peripheral portion of the projection lens  40  via the ring-shaped gap (the region  24 E having no infrared transmitting film) between an inner peripheral surface of the lens holder  30  and a peripheral portion of the infrared transmitting filter  20 C. Therefore, the peripheral portion  40   a  of the projection lens emits white light, thus diluting the red color of the light emitted from the projection lens  40  and making the red color less conspicuous.  
         [0052]    Furthermore, the forward and rearward lamp chambers divided by the filter  20 C communicate with each other via the gap  24 E between the filter  20 C and the lens holder  30 . Therefore, air convection occurs between the forward and rearward chambers via the gap, thus preventing retention of heat within the lamp chamber and reducing the possibility of thermal deterioration of the infrared transmitting film  22 .  
         [0053]    [0053]FIG. 7 is a longitudinal sectional view of an infrared radiating lamp constructed in accordance with a sixth embodiment of the invention.  
         [0054]    In an infrared radiating lamp  10 F in this embodiment, an infrared transmitting film  22  is formed directly on the rear surface of a projection lens  40 . A region  24 F having no infrared transmitting film and having a predetermined width is provided in a peripheral portion of the rear surface of the projection lens  40 .  
         [0055]    When the lamp is turned on, light from the light source reflected from the reflector  16 B passes through the infrared transmitting film  22 , as indicated by reference character L 6  in FIG. 7, whereby a visible light component is cut off. Therefore, light composed mainly of an invisible infrared component passes through the projection lens  40 . However, the outgoing light from the projection lens  40  still contains a visible light component (red light component) that is not cut off by the infrared transmitting film. Therefore, when the lamp is on, the projection lens  40  emits some amount of red light. However, light from the light source that does not pass through the infrared transmitting film  22  is directed to a peripheral portion of the projection lens  40  via the region  24 F having no infrared transmitting film, as indicated by reference character L 6 ′ in FIG. 7. Therefore, the peripheral portion  40   a  of the projection lens emits white light, thus diluting the red color of the light emitted from the projection lens  40  and making the red color less conspicuous.  
         [0056]    [0056]FIGS. 8 and 9 illustrate a seventh embodiment of the invention. FIG. 8 is a longitudinal sectional view of an infrared radiating lamp. FIG. 9 is an exploded perspective view of the lamp.  
         [0057]    In the infrared radiating lamp  10 G of this embodiment, an infrared transmitting film  22  is formed over a rear surface of a projection lens  40 , except for a flange portion  41  of the projection lens  40 . That is, the infrared transmitting film  22  is formed on a portion of the rear surface of the projection lens  40  corresponding to an expanded lens portion  42 . The flange portion  41  of the projection lens  40  is provided with a region  24 G having no infrared transmitting, film.  
         [0058]    Three stepped portions  32 C for retaining a projection lens  40  (a flange portion  41  thereof) are formed in a front opening portion of the lens holder  30  by cutting out an inner peripheral portion of the opening portion in a tapered fashion at three equidistant sites in the circumferential direction. Therefore, light from the light source that does not pass through the infrared transmitting film  22  is directed to the flange portion  41 . Reference numeral  33  indicates a tapered surface.  
         [0059]    A lens retainer frame  36 A is provided for securing the flange portion  41  of the projection lens  40  to a forward edge portion of the lens holder  30 . An inner peripheral portion of the lens retainer frame  36 A is cut out in an arcuate shape at three equidistant sites in the circumferential direction so that three hooks  37  are formed corresponding to the stepped portions  32 A of the lens holder  30 . Therefore, light from the light source directed to the flange portion  41  is emitted forward without being cut by the lens retainer frame  36 A. Reference numeral  38  indicates cutouts in an inner peripheral portion of the lens retainer frame  36 A.  
         [0060]    When the lamp is turned on, light from the light source reflected by the reflector  16 B passes through the infrared transmitting film  22 , as indicated by reference character L 7  in FIG. 8, whereby a visible light component is cut off. Therefore, light composed mainly of an invisible infrared component is emitted from the projection lens  40 . However, the outgoing light from the projection lens  40  still contains a visible light component (red light component) that is not cut off by the infrared transmitting film  22 . Therefore, when the lamp is on, the projection lens  40  emits some amount of red light. However, light from the light source transmitted through the region  24 G having no infrared transmitting film and not blocked by the stepped portions  32 C or the lens retainer frame  36 A (the hooks  37  thereof) (light from the light source that does not pass through the infrared transmitting film  22 ) is emitted from the flange portion  41  of the projection lens  40 , as indicated by reference character L 7 ′ in FIG. 8. Therefore, the peripheral portion  41  of the projection lens  40  emits white light, thus diluting the red color of the light emitted from the projection lens  40  and making the red color less conspicuous.  
         [0061]    In the foregoing embodiments, the infrared transmitting film is formed on the rear surface of the glass plate  21 , the front lens  14 ,  14 A, the projection lens  40 , etc. However, it is also possible to form an infrared transmitting film only on the front surface, or both the front and rear surfaces.  
         [0062]    Furthermore, in the foregoing embodiments the region having no infrared transmitting film is formed around the periphery of the infrared transmitting film, and the peripheral portion of the lens therefore emits white light so as to dilute the emission of red light from the lamp. However, it is also possible to employ a construction in which small pores, namely, small regions having no infrared transmitting film, are formed in the infrared transmitting film in a dispersed pattern so that a small amount of white light is emitted from a generally central portion of the lens. Furthermore, it is also possible to form a region having no infrared transmitting film around the periphery of the infrared transmitting film and to provide small pores as regions having no infrared transmitting film within the infrared transmitting film in a dispersed pattern so that the emission of red light from the lamp is diluted.  
         [0063]    As is apparent from the foregoing description, red light emitted from the lamp is diluted by white light emitted from a lens peripheral portion or a generally central portion of the lens. Therefore, unlike the conventional practice, the lamp does not appear to glow red. Hence, there is no danger that a driver or a pedestrian may falsely recognize the infrared radiating lamp as a tail lamp or a stop lamp. Correspondingly, safety can be assured.  
         [0064]    If a region having no infrared transmitting film is formed around the periphery of the infrared transmitting film, it is appropriate to form the infrared transmitting film by coating or vapor deposition after masking a portion corresponding to a region having no infrared transmitting film. Therefore, formation of the region having no infrared transmitting film is easier than in the case where a region having no infrared transmitting film is formed in a infrared transmitting film.  
         [0065]    Moreover, when it is necessary to replace the transparent member (including the infrared transmitting filter), it is appropriate to replace only the infrared transmitting filter without replacing other component parts of the lamp, thus reducing costs.  
         [0066]    Furthermore, since the transparent member is smaller in size than the lens, the number of pieces which can be produced per batch at the time of manufacturing the infrared transmitting films can be increased (i.e., the number of transparent members as which can be placed in a vapor deposition furnace is increased), and hence the costs involved in the formation of infrared transmitting films are reduced.  
         [0067]    Also, because an infrared transmitting film can be formed directly on the lens, the lamp structure becomes less complicated than in the case where an infrared transmitting film is formed on a transparent member. Furthermore, heat is not retained in the lighting chamber, so that the thermal deterioration of the infrared transmitting film is reduced. Hence, a stable amount of infrared light is secured over a long period of time.  
         [0068]    It should further be apparent to those skilled in the art that various changes in form and detail of the invention as shown and described above may be made. It is intended that such changes be included within the spirit and scope of the claims appended hereto.