FR2887506A1 - Target surface e.g. number plate, lighting device for motor vehicle, has reflectors reflecting light portion around light emitting diode axis and another portion separated from axis, towards surface`s nearby and distant regions respectively - Google Patents

Abstract

The device has a light emitting diode (4) (LED) emitting a light and a reflector (6) comprising two reflectors (61, 62). The reflector (61) is disposed in a region remote from the optical axis of the diode and reflects a part, of the emitted light, around the axis in the direction of a nearby region of a target surface e.g. number plate. The reflector (62) is disposed in a region included in the axis and reflects another part, of the emitted light, separated from the axis in the direction of a distant region of the surface.

Description

The present invention relates to a plate lighting device

  mineralogy (information plate) of a motor vehicle and more particularly a lighting device using a

  LED (a light-emitting diode) as a light source.

  As a device for illuminating a license plate, an incandescent lamp of the associated technique for a light source was used as in JP-2000-168438. However, the incandescent lamp poses a problem that its life is short and a large amount of time and labor is required to change the lamp when burned. In addition the amount of energy consumed is large, the stress imposed on the battery on board is important, the installation space is consistent and the degree of freedom of design concerning the license plate is low. Therefore, the use of the LED for the light source has been studied. Since the LED has a long life, small dimensions and low power consumption, it is possible to effectively solve the previously mentioned problems of the prior art of the incandescent lamp.

  When the LED is provided on one of the sides of the license plate and a light is projected from the LED to the surface of the license plate for carrying out a lighting operation, the surface of a region close to the LED diode can be illuminated so as to be brighter and the. The surface of a region farther away from the LED is dimmer so that it is darker.

  Similarly, such a problem arises in a technique using the incandescent lamp shown in JP-A-2000-168438. For this reason, JP-A-2000-168438 discloses uniform illumination almost over the entire surface of the license plate through the use of a stepped region in the scattering lens for diffusing light. However, the LED has a high directivity of the emitted light and the surface of a region disposed along an optical axis is bright and the surface of a region remote from the optical axis is dark.

  Even though the staged portion of the scattering lens is provided simply as in JP-A-2000-168438, it is impossible to solve the problem of nonuniform brightness. Therefore, there is a problem that it is difficult to uniformly illuminate the surface of the license plate by means of the LED.

  In addition, a plurality of LEDs may be provided around the license plate to uniformly illuminate the surface. However the number of LEDs is increased, so the cost is increased. In addition, it is impossible to avoid undesirable external exposure of the LED diode provided around the outside of the license plate. As a result, there is a problem that an external appearance is further impaired.

  An object of the present invention is to provide a device for illuminating a license plate which allows to uniformly illuminate the surface of a plate by means of an LED diode disposed on one side of the license plate.

  The invention provides a device for illuminating a license plate comprising a LED constituting a light source, a reflector for reflecting the light emitted by the LED diode towards a surface of the license plate, the reflector reflecting a light along an optical axis of the LED diode towards a region remote from the license plate and reflecting light exiting the optical axis of the LED diode towards a region adjacent to the license plate. More specifically, the reflector comprises a first reflector disposed in a region extending from the optical axis of the LED diode and a second reflector disposed in a region including the optical axis of the LED diode, a light reflected by the first reflector being reflected to the region adjacent to the license plate and light reflected from the second reflector being reflected towards the remote region of the license plate.

  More specifically, the invention may also be described as relating to a device for illuminating a target surface on a vehicle, characterized in that it comprises: a light-emitting diode which emits a light, and a reflecting reflector said emitted light, which is emitted by the light-emitting diode towards the target surface. The reflector reflects a first portion of the light emitted about an optical axis of the light emitting diode towards a region remote from the target, and reflects a second portion of the light substantially away from the optical axis. direction of a region close to the target surface.

  According to another characteristic of the invention, the reflector comprises a first reflector which is disposed in a region substantially remote from the optical axis; and a second reflector located in a region including the optical axis, and the first portion of the emitted light is reflected by the first reflector towards the neighboring region surrounding the optical axis, and the second portion of the emitted light is reflected by the second reflector towards the region distant from the latter.

  According to another characteristic of the invention, the first reflector reflects a third portion of the light towards an intermediate region, between the neighboring region and the remote region.

  According to another characteristic of the invention, the first reflector is made with a concave shape and the second reflector is made with a convex shape.

  In addition according to the invention, the first reflector reflects a part of the light towards an intermediate region between the region adjacent to the license plate and the region remote from this plate.

  According to another characteristic of the invention, the first reflector comprises a concave rotary surface obtained by rotation, about the optical axis, of a first segment on one side of the top of a parabola by positioning the light emitting diode of the light emitting diode. in that it is located at a focal point on the optical axis of the dish, and that the second reflector comprises a convex rotary surface obtained by rotating, around the optical axis, a portion of a second segment including a region crossing the optical axis of the parable.

  According to another characteristic of the invention, the reflector comprises a third plate-shaped reflector which reflects a light extending from the optical axis and not reflected by the first reflector, towards a lateral region of the target surface.

  In addition, there is provided a lens having a scattering step portion which refracts and diffuses a direct ray emitted by the light emitting diode towards the region adjacent to the target surface.

  The present invention has various advantages. For example, according to the invention, the light emitted by the LED which has a strong directivity starts from the optical axis and has a low light intensity is reflected by the first reflector to illuminate the region adjacent to the license plate.

  A light emitted along the optical axis and having an intense light intensity is reflected by the second reflector so as to illuminate the remote region of the license plate. For this reason, illumination of the license plate can be made in a substantially uniform manner so that the entire surface of the license plate can be illuminated with a substantially equal brightness. In particular, it is possible to improve the uniformity of the illumination by illuminating an intermediate region with a portion of the light reflected by the first reflector. By forming the second reflector with a convex configuration, it is possible to scatter the transmitted light along the optical axis with respect to the case where the second reflector is formed with a concave configuration. Therefore it is possible to improve the efficiency of use of a light. By further illuminating the number plate with light reflected from the third reflector and further light transmitted by a lens having the staggered diffusion portion, it is possible to further improve the uniformity of the illumination of the light. license plate.

  Other features and advantages of the present invention will become apparent from the description given below, taken with reference to the accompanying drawings, in which: - Figure 1 is a perspective view showing the appearance of a lighting device ; - Figure 2 is a sectional view taken along the line A-A in Figure 1; FIG. 3 is a fragmentary exploded perspective view showing an LED diode structure; FIG. 4 is a longitudinal sectional view showing the structure of the LED diode; FIGS. 5 (a) and 5 (b) are theoretical views for explaining a reflector; FIGS. 6 (a) and 6 (b) are circuit diagrams showing left and right LED diode structures; FIG. 7 is a view showing the directivity of an LED diode; Fig. 8 is a sectional view for explaining a lighting condition provided by the LED diode structure; and Fig. 9 is a front view for explaining the illumination state provided by the structure of the LED.

  FIG. 1 represents the schematic structure of a nonlimiting embodiment taken by way of example, in which a device for illuminating a number plate or registration plate according to the invention is applied to a vehicle. Figure 2 is a longitudinal sectional view taken along the line AA in Figure 1. Although the present embodiments specifically describe a license plate on a vehicle, one skilled in the art will understand that the embodiment is not limited to a license plate and may include any target surface, for example, but without limitation, an outer surface of a vehicle. Therefore, the term "target surface" includes, but is not limited to, the previously described license plate and surface thereof.

  Part of a rear panel RP in the vehicle is substantially concave and the surface of the substantially concave portion is slightly inclined upwardly with respect to a vertical plane. A substantially oblong LP plate is attached to the surface of the rear panel inclined in a substantially horizontal direction with a screw C or equivalent fixture.

  A cover portion OH formed by a protruding portion of the rear panel RP in the manner of a cover, is provided in the upper part of the LP license plate. An LED diode structure 1 is provided at a correct interval at two locations in the longitudinal direction of the LP plate respectively on the inside of the OH cap portion. The LED diode structure projects a light emitted by the LED diode onto the surface of the LP license plate to illuminate the surface of the LP license plate by adjusting the LED diode to form a light source as previously described. The two LED diode structures 1 comprise a right LED diode structure 1R and a left LED diode structure 1L.

  Fig. 3 is an exploded partial perspective view showing the detailed structure of the two left and right LED diode structures 1 (1R and 1L) and Fig. 4 is a longitudinal sectional view showing these structures. In a housing 2, consoles 22 protrude from both sides of a portion 21 of the housing, which has the shape of a cylindrical enclosure body and having a raised face and a bottom face which are respectively open. The casing 2 is fixed to the upper base face of the cover portion OH in the rear panel RP of the vehicle at the brackets 22, with a screw (not shown) as shown in FIG.

  A panel 3 is attached to an open face of a raised face side in the housing portion 21 and an LED 4 is mounted in a position near a lower side in a near-central position in a longitudinal direction of the surface. of the panel 3. In addition, a circuit component 5 for connecting the LED 4 is mounted on another part. The circuit component 5 is a resistor or any of a variety of well-known diodes, as previously described. An optical axis of the LED 4 is directed so that the diode emits light in a direction almost perpendicular to the surface of the panel 3. In addition, a reflector 6, which is a reflective plane obtained by treating a metal plate or forming a resin such as polycarbonate so as to deposit aluminum on a surface of this resin, or to make a reflective coating, is attached to a surface of the panel 3 and a first reflector 61, a second reflector 62 and a third reflector 63 are integrally formed with the reflector 6.

  As shown in FIGS. 5 (a) and 5 (b), the reflector 6 includes, as the first reflector 61, a reflector in which the inner surface of a rotatable concave surface is rotated, and this on one half around an optical axis Ox of the LED 5, a segment P1 on the side of a vertex Pp from the optical axis Ox in a parabola P by disposing the light emission point of the LED 4 so that it is almost a focal point. The above is used as a reflective plane.

  The reflector 6 includes, as the second reflector 62, a reflector in which the outer surface of a rotatable convex surface formed by rotation of a segment P2 having a predetermined length on the opposite side of the vertex, and this on a half around of the optical axis Ox of the LED 4. The previous surface is used as the reflecting plane essentially in the same way. As shown in FIG. 3, the reflector 6 comprises, as a third reflector 63, a plate-shaped portion having a small width and oriented substantially at right angles to the optical axis of the LED diode 4 of FIGS. two sides of the second reflector 62 in a longitudinal direction (a horizontal direction). The reflector 6 is fixed in one piece to the surface of the panel 3 by means of a screw or by welding.

  As shown in Fig. 3, a substantially rectangular transparent lens 7 formed of a resin is attached to an open surface on the underside of the housing portion 21. The lens 7 is formed by a white and transparent resin. Part of an inner surface of this lens is provided with a diffusing step portion 71 for refracting and diffusing slightly any of the lights emitted by the LED diode 4, which directly encounters the lens 4 from the LED diode 4 towards a substantially central region in the upper part of the LP license plate. A small concave-convex portion or a crimp is used for the diffusing staged portion 71. In addition, the lens 7 is attached to the housing 2 with a screw (not shown).

  The LED diode structure 1 is fixed to the upper base face of the cover portion 9 by adjusting the right LED diode structure 1R and the left LED diode structure 1L in right and left positions in FIG. the upper part of the oblong LP plate, i.e. respective central upper parts in the left and right regions, obtained by dividing the LP plate into two parts in a transverse direction. The panel 3 in the LED diode structure 1 is fixed so as to be oriented in a substantially vertical direction so as to be arranged in such a way that the optical axis Cx of the LED diode 4 and the surface of the lens 7 are oriented in a substantially horizontal direction and are overhanging the surface of the LP plate.

  A wiring connection connected to a power supply to be installed on board is executed for each of the panels 3 of the LED diode structures 1R and 1L on the right and left sides. Fig. 6 (a) is a wiring circuit diagram, in which the LEDs 4 (4R and 4L) on the right and left sides are coupled together in series through resistors R1 and R2 to obtain a drop in voltage. In addition, a rectifier diode D is coupled in series with an energy supply installed on board (+ 13.5 V). Therefore, the two LEDs 4R and 4L are coupled together in series so that the same current (for example 350 mA) flows in the direction of each of the LEDs, so that they emit light. Therefore the energy consumed is 4.73 W. On the other hand, in another embodiment taken by way of example and not limitation, as shown in Figure 6 (b), LEDs 4L and 4R are provided respectively independently. In other words, the resistors R1 and R2, the rectifying diodes D1 and D2 and the Zener diodes ZD1 and ZD2 are respectively coupled to the LED diodes 4R and 4L and are independently coupled respectively to the power sources installed in the vehicle, to emit light Substantially the same current (350 mA) is circulated in the LEDs 4R and 4L respectively for emitting light.

  Therefore, the energy consumed in each of the LEDs of Figure 6 (b) is equal to 4.73 W and the total energy consumed is twice this value, that is to say 9.46 W Consequently, by connecting the two LED diode structures 1R and 1L in series as in the non-limiting embodiment taken as a title.

  for example, it is possible to reduce by approximately half the energy consumed. In addition, it results from a comparison between the two circuit arrangements that Zener diodes ZD1 and ZD2 are not required and that one of the rectifying diodes can be omitted. In addition, the number of components can be reduced.

  According to the device for illuminating a number plate having the structure described above, when the power supply is sent to the LED 4 by means of the panel 3 so as to cause the LED 4 to emit light, the light emitted by the LED 4 is reflected by the reflector 6 and is transmitted by the lens 7 or is transmitted directly by the lens 7, which illuminates the surface of the LP license plate. The directivity of the LED 4 is shown in Fig. 7 and is reduced to about "1/2" for an angle of 30 degrees if the light intensity of the optical axis Ox is set to about "1".

  As shown in a view showing a light path from the side of the LP plate in FIG. 8, a light emitted by the LED 4 in the direction of the optical axis Ox is reflected by the second reflector 62 almost vertically, downward. At least for this reason, the reflected light is reflected back to the lower region of the LP plate, i.e. a remote region seen from the LED 4. At the same time, the same light is reflected so that be diffused in a direction around the optical axis, depending on the shape of the rotating surface of the second reflector 62. Therefore a lower region S2 of the mineral plate Lp is illuminated in FIG. 9, which shows a characteristic of light distribution viewed from the front face of the right half portion of the LP license plate in the form of a thick solid line.

  Any light emitted by the LED diode 4 from the optical axis Ox is emitted from the optical axis Ox and has a relatively weak light, and is the top with intensity reflected vertically and down by the For this reason, as shown on the light reflected towards the region, the mineralogical plate LP, that is to say a view from the LED diode 4. Significantly reflector 61. Figure 8, the neighboring region superior simultaneously, the light is also reflected so as to be scattered about the optical axis, depending on the shape of the rotating surface of the first reflector 61.

  As shown in Fig. 9, the upper region of the LP plate or an intermediate region S1 is illuminated. A light emitted at an angle with respect to the optical axis Ox as a function of the directivity of the LED diode 4 shown in FIG. 7 has a low luminous intensity. Therefore, the illumination of the upper part of the intermediate region S1 in the LP plate is lower than that of a lower region.

  As shown in FIG. 9, a light emitted upwards from the optical axis Ox by the LED diode 4 and towards external sides of the first reflector 61 and not reflected by the first reflector 61, is reflected substantially vertically and downwards by the third reflector 63 towards both sides in the transverse direction of the LP plate. Consequently, the left and right regions 3R and 3L in the upper region, that is to say in the region adjacent to the LP plate, are illuminated by a light reflected by the third reflector 62 and having a low luminous intensity. .

  In addition, the light emitted downwardly from the optical axis Ox by the LED 4 is refracted and scattered by the scattering step 71 when it is transmitted through the lens 7 and is refracted and diffused towards almost the central portion of the upper region of the LP plate, as shown in FIG. 8. As shown in FIG. 9, a central portion S4 of the upper region of the LP plate is illuminated by a light transmitted by the lens 7. Therefore the upper part of the LP plate is illuminated in a state in which the light reflected by the first reflector 61, the light reflected by the third reflector 63 and the light transmitted by the lens 7 are superimposed.

  As previously described, with reference to FIG. 9, the lower part S2 of the LP plate is illuminated by a light emitted around the optical axis of the LED diode 4 having a high luminous intensity. Even though an optical path length from the LED 4 is large, the illumination can be achieved with brightness.

  Although the intermediate region S1 in the vertical direction of the LP license plate is illuminated by a light substantially distant from the optical axis of the LED diode 4 and having a low light intensity, the optical path length from the LED diode 4 is substantially short. Therefore, the lighting is obtained with a brightness substantially equal to the brightness of the lower region S2. Although the upper region of the LP mineral plate is illuminated by the light substantially remote from the optical axis of the LED diode 4 and having a low light intensity, the illumination is obtained in superposition with a direct radiation transmitted by the LED diode 4 from the LED 4 through the lens 7. Therefore, the lighting is obtained with brightness equal to a brightness of the lower region S2 or the intermediate region S1. Therefore, the illumination can be obtained with brightness substantially equal over the entire surface extending from the upper region to the lower region in the right zone of the LP plate.

  The description will be given of the state in which the right half of the LP license plate is illuminated by means of the right LED diode structure 1R provided on the right side with respect to the LP license plate with respect to FIG. 9. In addition, the left half of the LP license plate can also be illuminated in the left LED diode structure 1L. Likewise in the left LED diode structure 1L, any of the lights emitted by the LED diode which has a high light intensity, includes an optical axis and is transmitted by means of the optical axis and illuminates a light. remote region of the LP plate, a light having a low light intensity and out of the optical axis which illuminates the region adjacent to the LP plate. Therefore, it is possible to uniformly illuminate almost the entire surface of the left area of the LP license plate.

  Although the description has been given for the example in which the reflector 6 is constituted by the first to third reflectors 61 to 63 in Example 1, it is constituted in the form of a LED diode structure suitable for to uniformly illuminate almost the entire surface of an LPx license plate, which is compatible in Europe and has a horizontal length as represented by a broken line in thick line in Figure 9. When the horizontal length is low as in the LP plate in Japan, which is represented by a solid line in solid line in Figure 9, a region to be illuminated by the third reflector 63 is less than that shown in Figure 9. Therefore it is possible to form the third reflector 63 so that it has weak. dimensions. Depending on the conditions, it is also possible to delete the third reflector. Depending on a positional relationship between the LED and the reflector 6, the third reflector may be formed only on one side.

  In the preceding non-limiting embodiment given by way of example, the second reflector 62 is arranged in the form of a convex rotary reflecting surface. Therefore, it is possible for the second reflector to reflect part of the light emitted downwards from the optical axis Ox of the LED 4, in particular a light in the vicinity of the optical axis Ox in a diffusion state, which causes illumination of the extended region of the LP license plate. This is why the light emitted by LED 4 can be. used in an efficient and practical way, which allows to realize the lighting. When the second reflector has substantially the same surface

  concave rotary reflector as the first reflector, the light emitted in the direction of the optical axis of the LED can not be reflected in a state of diffusion towards the license plate, which is a disadvantage for a diffusion efficiency around the optical axis. Depending on the shape of a parabola constituting the reflector, it is also possible to provide an arrangement for increasing the surface of the second reflector and for illuminating the intermediate region of the license plate with a portion of the light reflected by the second reflector .

  Although the description focused on the example. in which the two LED diode structures are respectively provided on the left and right sides of the license plate, it is also possible to use a structure, in which a single LED diode structure is provided in the central position of the license plate, when the light intensity of the LED is high and the entire surface of the license plate can be illuminated with a brightness by an LED, and furthermore when the directionality of the LED is low and the the entire surface of the license plate can be illuminated uniformly by the reflector and the lens.

  In addition, the lens diffusion step may be performed as a stepped refractive portion or a converging or collecting step, corresponding to the reflection characteristic of the light in the reflector, or these portions storages can be mixed.

  It will be apparent to those skilled in the art that various changes and modifications can be made to the described preferred embodiments of the present invention without departing from the scope of the present invention.

Claims (7)

  A device for illuminating a target surface on a vehicle, characterized in that it comprises: a light-emitting diode (4) which emits light, and a reflector (6) which reflects said emitted light, which is emitted by the light-emitting diode (4) towards the target surface, and in that the reflector (6) reflects a first part of the light emitted around an optical axis Ox of the light-emitting diode (4) towards a region remote from the target, and reflects a second portion of the light substantially away from the optical axis towards a region close to the target surface.   2. Device according to claim 1, characterized in that the reflector (6) comprises: a first reflector (61) which is disposed in a region substantially remote from the optical axis (0x); and a second reflector (62) located in a region including the optical axis, and in that the first portion of the emitted light is reflected by the first reflector (61) towards the neighboring region surrounding the optical axis, and that the second portion of the emitted light is reflected by the second reflector (62) towards the region remote from the latter.   3. Device according to claim 2, characterized in that the first reflector (61) reflects a third portion of the light towards an intermediate region, between the neighboring region and the remote region.   4. Device according to claim 2, characterized in that the first reflector (61) is made with a concave shape and in that the second reflector (62) is made with a convex shape.   5. Device according to claim 2, characterized in that the first reflector (61) comprises a concave rotary surface obtained by rotation, about the optical axis (0x), of a first segment on a sum side of the vertex of a parabola P by positioning the. light-emitting diode (4) so that it is located at a focal point on the optical axis of the dish, and the second reflector (62) comprises a rotatable convex surface obtained by rotating about the optical axis ( 0x), a part of a second segment including a region intersecting the optical axis of the parabola (P).   6. Device according to claim 1, characterized in that the reflector comprises: a third reflector (63) in the form of a plate which reflects light from the optical axis and not reflected by the first reflector (61), in the direction of a lateral region of the target surface.   7. Device according to claim 1, characterized in that it further comprises a lens (4) having a scattering step portion (71) which refracts. and diffuses a direct ray emitted by the light-emitting diode (4) towards the region close to the target surface.