Patent Application
20180031196
The present disclosure relates to an illumination device, method and system and particularly, but not exclusively, to a lighting apparatus for use in a vehicle headlight. Aspects of the invention relate to an illumination system, an illumination device for use as a vehicle headlight, a method for providing illumination or illuminating light for use as a vehicle headlight, and to a vehicle.
Illumination devices for use in vehicle headlights may include an excitation light source provided in combination with a fluorescent substance. These devices are configured such that the excitation light source irradiates the fluorescent substance with excitation light. The fluorescent substance absorbs at least a portion of received excitation light and emits illuminating light in response thereto. The illumining light may then be projected forward from the illumination device to illuminate an area in front of the vehicle. However, the excitation light may have high coherence which makes it potentially hazardous as exposure of such light to parts of the human eye can permanently damage a person's sight. Therefore, it is of great importance that the excitation light is contained within the illumination device.
Additionally, illumination devices for use in vehicle headlights may be required to project different spatial light distributions. For example, vehicle headlights are typically required to project a low beam distribution and a high beam distribution. While high beam distributions generally cast illuminating light straight ahead of the vehicle, low beam distributions generally limit the height to which light is cast to prevent dazzling road users. Low beam distributions also typically cast light sideward, such as rightward (in right-hand traffic countries) or leftward (in left-hand traffic countries).
It is an object of certain embodiments of the invention to prevent potentially dangerous excitation light from leaking from an illumination device for use in a vehicle headlight.
Furthermore, it is an object of certain embodiments of the invention to control the distribution of the light projected by an illumination device for use in a vehicle headlight. It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art.
Aspects and embodiments of the invention provide an illumination device for use as a vehicle headlight, an illumination system optionally comprising aforesaid illumination device, a method of providing illumination or illuminating light for use as a vehicle headlight, and to a vehicle as claimed in the appended claims.
According to an aspect of the invention, there is provided an illumination device for use as a vehicle headlight. The device may comprise at least one excitation means for emitting excitation light. The device may comprise a fluorescing means for receiving at least a portion of the excitation light and emitting illuminating light in response thereto in an illumination direction of the illumination device. The device, when used as a vehicle headlight, may provide a lower rate of power consumption when compared to that of a conventional vehicle headlight.
According to another aspect of the invention, there is provided an illumination device, comprising the illumination device of the abovementioned aspect, wherein the at least one excitation means is arranged substantially perpendicular to, or forward of, the fluorescing means in the illumination direction to emit excitation light toward the fluorescing means. This arrangement may prevent excitation light from being emitted from the device in the illumination direction.
An illumination device of the either of the above aspects, wherein: said means for emitting excitation light comprises an excitation light source; and said means for receiving at least a portion of the excitation light and emitting illuminating light in response thereto comprises a fluorescent material.
Optionally, the at least one excitation means may be provided as a radial array of two or more excitation means which are arranged to direct emitted excitation light radially inward toward the fluorescing means.
In some embodiments, the illuminating light is emitted in the illumination direction through a central region of the radial array. In some embodiments, the illumination device further comprises a housing arranged to support the at least one excitation means in relation to the fluorescing means. Further, the housing may comprise an opening though which the illuminating light is directed, in use, in the illumination direction.
Optionally, the housing may comprise an annular portion, wherein the radial array of two or more excitation means may be arranged around the annular portion.
In some embodiments, the two or more excitation means are generally equally spaced around the annular portion. The opening may be provided as a central region of the annular portion. Further, the at least one excitation means may be arranged to emit the excitation light in a direction at least partly opposed to the illumination direction.
The at least one excitation means may be arranged forward of the fluorescing means in the illumination direction at an angle within a range of 5 to 85° relative to the illumination direction. In some embodiments, the housing may form a channel having front and rear openings. Optionally, an axis of the channel substantially corresponds to the illumination direction.
In some embodiments, the illuminating light is directed, in use, toward the front opening of the housing. In some embodiments at least one projecting means is arranged at a front opening of the housing. Optionally, the projecting means may be provided as a lens. In some embodiments the illumination device further comprises a reflecting means attached to the rear opening of the housing. Optionally, the reflecting means may be provided as a casing.
Optionally, the fluorescing means may be arranged generally within the reflecting means. Further, the illumination device may also comprise a reflecting surface arranged to a rear of the fluorescing means for directing illuminating light in the illumination direction. The reflecting surface may be arranged upon an interior surface of the reflecting means.
In some embodiments, the housing may be generally cylindrical and the front and rear openings may be arranged to respective ends of the housing.
Optionally, the at least one excitation means may be arranged to irradiate one or more predetermined regions of the fluorescing means with the excitation light.
Optionally, the housing may be arranged to provide a thermal conduit for the at least one excitation means. The housing may form a heat sink for the at least one excitation means. The housing may comprise a plurality of heat dissipating fins. The housing may comprise a plurality of sockets, wherein each excitation means may be received in a respective socket.
According to a further aspect of the invention, there is provided a method of providing illuminating light for use as a vehicle headlight, comprising: emitting excitation light from at least one excitation means toward a fluorescing means where the excitation means is arranged substantially perpendicular to, or forward of, the fluorescing means; and emitting, by the fluorescing means, illuminating light in an illumination direction of the illumination device. The method may prevent excitation light from being emitted from the device in the illumination direction.
The method of providing illuminating light of the above aspect, wherein: said means for emitting excitation light comprises an excitation light source; and said means for receiving at least a portion of the excitation light and emitting illuminating light in response thereto comprises a fluorescent material.
According to yet another aspect of the invention, there is provided an illumination device for use as a vehicle headlight, comprising: a plurality of excitation means for emitting excitation light; and a fluorescing means for receiving at least a portion of the excitation light emitted by the excitation means and emitting illuminating light in response thereto; wherein the plurality of excitation means are spaced around the fluorescing means and each light source is independently operable to control a distribution of illuminating light emitted by the fluorescing means. The plurality of excitation means are independently operable to control a distribution of light emitted by the florescence material so as to permit the alteration of the spatial distribution of illuminating light.
An illumination device of the above aspect, wherein: said means for emitting excitation light comprises an excitation light source; and said means for receiving at least a portion of the excitation light and emitting illuminating light in response thereto comprises a fluorescent material.
Optionally, each of the plurality of excitation means may be arranged to irradiate a respective region of the fluorescing means with the excitation light to thereby control the distribution of illuminating light. The at least one excitation means may be provided as a radial array of two or more excitation means which may be arranged to direct emitted excitation light radially inward toward the fluorescing means.
In some embodiments, the illuminating light is emitted in the illumination direction through a central region of the radial array.
According to yet another aspect of the invention, there is provided an illumination system, comprising: an illumination device of the aforementioned aspects; and a control means arranged to selectively cause at least some of the plurality of excitation means to emit excitation light toward the fluorescing means.
An illumination system of the above aspect, wherein said means arranged to selectively cause at least some of the plurality of excitation means to emit excitation light toward the fluorescing means comprises a control unit.
In some embodiments, the control means may be arranged to: selectively cause a first group of the excitation means to emit excitation light to form a first distribution of illuminating light; and selectively cause a second group of the excitation means to emit excitation light to form a second distribution of illuminating light. The first and second distributions may be different spatial distributions of illuminating light.
Optionally, the first distribution of illuminating light may be a dipped-beam pattern and the second distribution may be a full-beam pattern. The first distribution of illuminating light may be for use on a left-hand driving roadway pattern and the second distribution may be for use on a right-hand driving roadway.
In some embodiments, the first group of the excitation means and the second group of the excitation means may comprise at least some common excitation means.
According to a yet a further aspect of the invention, there is provided method of providing illumination for use as a vehicle headlight, comprising: selectively causing one or more of a plurality of excitation means spaced around a fluorescing means to emit excitation light toward the fluorescing means, wherein the fluorescing means is arranged for receiving at least a portion of the excitation light emitted by the excitation means and emitting illuminating light in response thereto and the one or more of the plurality of excitation means are selected to control a distribution of illuminating light emitted by the fluorescing means. The plurality of excitation means are independently operable to control a distribution of light emitted by the florescence material so as to permit the alteration of the spatial distribution of illuminating light.
An illumination device of the above aspect, wherein: said means for emitting excitation light comprises an excitation light source; and said means for receiving at least a portion of the excitation light and emitting illuminating light in response thereto comprises a fluorescent material.
Optionally, the method of the aspect may further comprise: selectively causing a first group of the plurality excitation means to emit excitation light to form a first distribution of illuminating light; and selectively causing a second group of the plurality excitation means to emit excitation light to form a second distribution of illuminating light. The first and second distributions may be different spatial distributions of illuminating light.
In some embodiments, the first distribution of illuminating light may be a dipped-beam pattern and the second distribution may be a full-beam pattern. The first distribution of illuminating light may be for use on a left-hand driving roadway pattern and the second distribution may be for use on a right-hand driving roadway.
According to another aspect of the invention, there is provided a vehicle comprising an illumination device or an illumination system of the abovementioned aspects.
Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.
Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which:
Referring to
The excitation means may be provided as a plurality of laser modules 12 which may, in some embodiments, be arranged as a radial array of laser modules 12. It will be understood that in certain embodiments a single laser module 12 may be alternatively provided. In other embodiments the excitation means may also be provided in alternative forms, for example as one or more high-power light emitting diode (“LEDs”) or semi-conductor diodes.
The fluorescing means may be provided as at least one florescent block 14. The florescent block 14 may be formed from at least one fluorescent material, such as phosphor, which may be a silica based phosphor. The block 14 may also incorporate other materials, for example a diffusion material, such as alumina, for diffusing light received from the laser modules 12. Materials for improving thermal conductivity of the fluorescing means may also be incorporated therein, e.g. diamond powder. At least one binder material may also be incorporated in the florescent block 14, for example a polymeric resin, for binding multiple materials used to form the block 14. It will be understood that other or alternative materials may be included in the at least one florescent block 14. Further, the fluorescing means 14 may be provided in an alternative form, for example a surface covering or coating. The coating or covering may be applied to a component or a surface the illumination device 10.
The radial array of laser modules 12 may be spaced around a circumference of a substantially annular housing 16. In the embodiment shown in
The number of laser modules 12 is not material, while six are illustrated in the accompanying figures, the number of modules may be, for example, between one and ten. Furthermore, the spacing between each of the laser modules need not be equal and, in other embodiments, the spacing may vary about the circumference of the housing 16.
The housing 16 may be formed by casting, by machining or in any other convenient manner. While a one-piece cast housing is depicted in
As mentioned above, the modules 12 may be configured to direct respective beams of collimated laser light radially inwardly toward the florescent block 14. At least a portion of the laser light emitted by the modules 12 may irradiate the block 14. In use, the block 14 absorbs at least a portion of the received excitation light and emits illuminating light. The illuminating light may be substantially white light. The laser diodes 12 in combination with the florescent block 14 may produce high-contrast white light within a range of colour temperatures, for example from 5500 to 6000 K. The rate of power consumption of each of the diodes 12 may be less than 10 W and may be, by way of example, between 1 and 5 W. Therefore, the power consumption of the device 10 may be significantly lower than that of a conventional vehicle headlight, for example a halogen headlight which may have a power consumption rate exceeding 120 W.
In certain embodiments, one or more collimating lenses (not shown) may also be provided to focus the beams of laser light on the block 14. The one or more collimating lenses may be arranged between the laser module 12 and the florescent block 14 to collimate laser light passing therethrough. Furthermore, the laser light may have a high level of directivity so that each of the laser modules 12 may be configured to irradiate only a respective predetermined region of the block 14.
The reflecting means may be provided as a rear casing 30. The casing 30 may be shaped like a dome or cupola. The casing 30 may be attached to the rear of the housing 16 such that it occludes the rear opening 22. The casing 30 may form a hollow body with a reflecting interior surface 32 whereby the surface 32 may at least partially surround the florescent block 14. The block 14 may be held inside the casing 30 by a support 34. The casing 30 may be formed from a metal with a high reflectivity, such as aluminium, thus inherently providing the reflecting surface 32. Alternatively, the reflecting surface 32 may be provided on at least a portion of the casing 30 by a reflective film attached to the interior surface 32. The film may be provided as a metal film, such as silver or aluminium. A film may be formed on the casing 30 in embodiments where the casing 30 is made from a non-metallic or non-reflective material. In certain other embodiments a separate reflecting element may be provided within the casing 30 and/or the hollow body of the housing 16.
The casing 30 and the reflecting surface 32 may be provided in the form of a parabolic mirror which has a focal point 36. The support 34 may position the florescent block 14 at the focal point 36 so that at least a portion of the illuminating light emitted by the block 14 is reflected at the reflecting surface 32 to form a generally collimated beam of illuminating light. The collimated beam may be directed along an axis of illumination A. A cooling fan 38 may be provided to dissipate heat generated by the phosphor block 14. The support 34 may provide a heat sink for the same purpose. A collet member 39 having a plurality of fins and arranged at the rear of the device 10 may provide a further heat sink.
The projecting means may be formed as at least one lens 40. The lens 40 may be attached to a front of the housing 16. The shape of the lens 40 may correspond to the shape of the opening 20 and may be attached to the housing 16 so as to occlude the front opening 20. When attached in this manner, the lens 40 prevents foreign object debris from entering the illumination device 10. The lens 40 has an optical axis which may coincide with the direction of illumination A. Illuminating light directed along the axis A travels in a forward direction, leaving the rear casing 30 to pass through the circular channel 18 and may be projected from the device 10 via the front opening 20 and lens 40. The lens 40 may be arranged to distribute the beam of collimated light in front of the vehicle. The lens 40 may configure the distribution of light to provide satisfactory illumination of the area in front of the vehicle.
As illustrated in
Other means to reduce the risk of leakage of high coherence light may be incorporated in the device 10, such as filters or light scattering materials formed on the lens 40. However, if components of the device 10 were to become damaged or worn the excitation light may be projected from the device 10. The rear facing arrangement of the laser modules 12, as described above and illustrated in
In the embodiment illustrated in
The laser modules 12 may be independently operable, i.e. each of the modules 12 may be switched on and off independently of the others. Therefore, in use, only at least one predetermined region of the block 14 may be irradiated with laser light by selectively operating a subset of the laser modules 12. That is to say areas of the block 14 may be selectively irradiated by controlling the operation of the laser modules 12. Furthermore, the intensity of each of the modules 12 may be independently variable between a minimum intensity and a maximum intensity to selectively control the intensity of the irradiating laser light over each predetermined region. By independently operating a subset of the modules 12, or controlling a relative intensity of each of the modules 12, the distribution of illuminating light emitted by the block 14 may be manipulated. Consequently, multiple spatial distributions of the illuminating light protected from the device 10 may be formed. The spatial distributions are formed responsive to control of the laser modules 12.
Similarity,
It will be understood that many spatial distributions of illuminating light cast in front of the vehicle 100 are possible. The spatial distributions of illuminating light correspond with many possible radial distributions of light emitted by the block 14. The exact number and shape of possible spatial distributions may vary in other embodiments depending on the number and arrangement of the laser modulus 12. Further, the shape of the possible spatial distributions may be affected by the shape of the reflecting surface 32 and/or the shape of the lens 40 and/or the shape of the fluorescent block 14.
The laser modules 12 may be selectively operated under the control of a control means in the form of a control unit, e.g. an Electronic Control Unit (“ECU”). An ECU is a conventional feature for monitoring and controlling various aspects of the vehicle 100. Accordingly, the function and means of operation of the ECU will not be described in detail. The laser modules 12 in combination with the ECU may form an illumination system provided within the vehicle 100. The ECU may perform a method of selectively operating one or more subsets of the lasers modules 12 to form one or more distributions of illuminating light in front of the vehicle 100. The method may comprise the ECU selectively operating one or more subsets of laser modules 12 to form one or more predetermined distributions of illuminating light in front of the vehicle 100. The predetermined distributions may, for example, correspond to high and low beam distributions. Alternatively, or in addition, the predetermined distributions may, for example, correspond to distributions suitable for left-hand traffic or right-hand traffic countries.
The modules 12 may be selectively operated under automated control of the ECU to alter the distribution of illuminating light, for example in response to changes in driving conditions, such as if the vehicle 100 transitions from suburban roads to motorways. By way of example, such a transition could be indicated by a change in the vehicle's 100 speed which is monitored by the ECU. In response to changes in driving conditions the ECU may cease selective operation of one or more subsets of laser modules 12 and initiate selective operation of one or more alternative subsets. In this manner the ECU may selectively control the laser modules 12 to alternate between one or more predetermined distributions of illuminating light, for example high beam and low beam distributions. Of course, the laser modules 12 may be operated, via the ECU, by manual controls operated by the vehicle's user.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1502975.4 | Feb 2015 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/053428 | 2/18/2016 | WO | 00 |
