Infrared Illuminator

Abstract

An infrared illuminator including an infrared emitter and an infrared window for transmitting infrared radiation from the infrared emitter to a field of illumination. The infrared window includes an electrochromic material for varying the transmittance of the infrared radiation through the infrared window in response to an applied electric field.

Claims

1. An infrared illuminator comprising: an infrared emitter; and an infrared window for transmitting infrared radiation from the infrared emitter to a field of illumination, the infrared window comprising: a electrochromic material for varying the transmittance of infrared radiation through the infrared window in response to an applied electric field.

2. The infrared illuminator according to claim 1, wherein the electrochromic material is changeable between a transparent state and an opaque state in response to the application of the applied electric field.

3. The infrared illuminator according to claim 2, wherein the electrochromic material in the opaque state forms a diffuser pattern for reducing transmittance of infrared radiation through the infrared window.

4. The infrared illuminator according to claim 3, wherein the electrochromic material is polyelectrochromic.

5. The infrared illuminator according to claim 4, wherein the electrochromic material includes a plurality of opaque states having different transmittances of infrared radiation.

6. The infrared illuminator according to claim 1, wherein the infrared window comprises one or more controllable regions of electrochromic material within which the transmittance of infrared radiation may be varied in response to the electric field applied to the respective region.

7. The infrared illuminator according to claim 6, wherein the one or more controllable regions comprise a plurality of controllable regions.

8. The infrared illuminator according to claim 7, wherein the infrared window comprises a plurality of electric field conductors for independently applying an electric field to a subset of the plurality of controllable regions.

9. The infrared illuminator according to claim 8, wherein the subset of the plurality of controllable regions is an individual controllable region.

10. The infrared illuminator according to claim 9, wherein the plurality of controllable regions are arranged in a grid array.

11. The infrared illuminator according to claim 1, further comprising a housing configured to enclose the infrared emitter.

12. The infrared illuminator according to claim 11, wherein the housing comprises an aperture, the aperture in a front-facing portion of the housing.

13. The infrared illuminator according to claim 12, wherein the infrared window is located in the aperture.

14. The infrared illuminator according to claim 1, further comprising: a controller for applying an electric field to the infrared window for varying the transmittance of infrared radiation therethrough.

15. The infrared illuminator according to claim 14, wherein reducing the transmittance of infrared radiation through the infrared window reduces the field of illumination.

16. The infrared illuminator according to claim 1, wherein the infrared emitter comprises a vertical-cavity, surface-emitting lasers (VCSEL) emitter having an emitter surface.

17. The infrared illuminator according to claim 16, wherein the emitter surface is parallel to the infrared window.

18. The infrared illuminator according to claim 1, wherein the infrared illuminator is an automotive infrared illuminator.

19. The infrared illuminator according to claim 18, wherein the infrared window comprises one or more controllable regions of electrochromic material within which the transmittance of infrared radiation may be varied in response to the electric field applied to the respective region.

20. The infrared illuminator according to claim 19, wherein the field of illumination is altered based on a proximity to eyes of an occupant in an automobile.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Illustrative implementations may now be described with reference to the accompanying drawings in which:

[0015] FIG. 1A illustrates a schematic illustration of an illuminator according to a first implementation;

[0016] FIG. 1B illustrates a plan view of the IR window through section A-A shown in FIG. 1A;

[0017] FIG. 2A illustrates a schematic illustration of an illuminator according to a second implementation;

[0018] FIG. 2B illustrates a plan view of the IR window through section A-A shown in FIG. 2A;

[0019] FIG. 3A illustrates a schematic illustration of an illuminator according to a third implementation; and

[0020] FIG. 3B illustrates a plan view of the IR window through section A-A shown in FIG. 3A.

DETAILED DESCRIPTION

[0021] FIG. 1A illustrates a schematic illustration of an illuminator according to a first implementation. As illustrated, an illuminator 1 according to a first implementation is shown in FIG. 1A. The illuminator package houses an IR emitter 2, which is supplied by an external power source 5. In this implementation, the IR emitter 2 is a VCSEL emitter. In other implementations, the emitter 2 may be an IR LED. The IR emitter 2 is positioned for directing emitted IR light forward out of an aperture at the front of the illuminator 1.

[0022] The aperture at the front of the illuminator 1 is provided with a controllable IR window 3 having electrochromic properties. The IR window 3 is an optical window for allowing IR light to be transmitted to the field of illumination 4, and in implementations may form part of the illuminator's lens or diffuser assembly.

[0023] In this implementation, the transparency of the whole IR window 3 may be varied under the control of controller 6 in order to vary the intensity of IR light transmitted therethrough. As such, the intensity of IR light output by the illuminator 1 onto the field of illumination 4 may be adjusted under the control of the controller 6.

[0024] In this connection, the IR window 3 includes an electrochromic material applied to a substrate, together with two electric field conductors. In use, the optical properties of the IR window 3 can be varied by the controller 6 applying a voltage to the electric field conductors for generating an electric field through the electrochromic material. This application of an electric field changes the state of the electrochromic material producing a visible diffusor pattern 7 in the window 3. This is shown in FIG. 1B which illustrates a plan view of the IR window 3 through section A-A shown in FIG. 1A. In this colored or opaque state, the transmittance of IR light through the window 3 is reduced. Conversely, the controller 6 may apply an inversed electric field to remove the diffuser pattern 7 by transitioning the electrochromic material to a bleached or transparent state. In this state, IR light is emitted at its maximum intensity. Accordingly, by varying the state of the electrochromic material the field of illumination 4 may be variably dimmed depending on the requirements of the specific application.

[0025] Notably, the electrochromic color change through the IR window 3 is persistent. Consequently, the controller 6 only needs to apply an electric field to adjust the transmittance for the required application. Once set, the IR window 3 therefore retains its dimming setting, without requiring ongoing active driving by the controller 6. That said, the controller may periodically update the dimming setting by reapplying the appropriate electric field.

[0026] In implementations, the electrochromic material applied to the IR window 3 may be polyelectrochromic in that it may have a plurality of opaque states having different levels of transmittance. In such implementations, the contrast of the diffuser pattern 7 may be varied depending on the magnitude of the electric field applied, and hence the transmittance of IR light can be more finely adjusted.

[0027] With the above arrangements, the overall intensity of IR light provided by the illuminator 1 may be adjusted for different applications. For example, in use cases in smaller vehicles, where the illuminator 1 may be located relatively close to a driver, the intensity of IR light may be reduced to mitigate risk of eye damage. Conversely, in larger vehicles, a higher transmissibility setting may be adopted for the IR window 3 to optimize for the enlarged cabin space. Nevertheless, in implementations, the same IR illuminator unit may be used in both cases, thereby providing for economies of scale.

[0028] A second implementation is shown in FIGS. 2A and 2B. This implementation operates in substantially the same way as the first implementation, except that the controllable IR window 3 in this implementation includes a plurality of independently controllable electrochromic cells 8. These cells 8 are shown in FIG. 2B, with the transmittance of each cell being independently adjustable. The controller 6 includes a row-column driver for applying an electric field to individual cells 8 to adjust their transparency. As such, the transmittance of IR light through different regions of the IR window 3 may be adjusted by applying electric fields to cells 8 within those regions. Accordingly, the field of illumination and the intensity of illumination can be adjusted depending on the requirements of the specific application. For example, a smaller field of illumination may be provided for smaller vehicles by reducing the transmission of IR light through cells 8 around the periphery of the window 3. Equally, the intensity of IR light applied to the eye region of vehicle occupants may be reduced by dimming cells 8 at the top of the IR window 3 for mitigating the risks of eye damage. This thereby provides a flexible solution allowing a standard illuminator unit to be configured for a large variety of different applications.

[0029] FIG. 3A illustrates a schematic illustration of an illuminator according to a third implementation. Further, FIG. 3B illustrates a plan view of the IR window through section A-A shown in FIG. 3A. A third implementation is shown in FIGS. 3a and 3b. This implementation operates in substantially the same way as the first and second implementations, except that the IR window 3 in this implementation includes an independently controllable zone 9, as shown in FIG. 3B. The controller 6 includes a zonal driver for adjusting the transparency of the zone 9 within the window 3. As with the second implementation, this thereby allows the field and intensity of illumination to be adjusted for different applications. In this example, the controllable zone 9 is provided at the top of the IR window for providing localized dimming in regions of the field of illumination 4 where a vehicle occupant's eyes are. As such, in smaller vehicles where the illuminator may be closer to an occupant, the intensity of IR light emitted may be reduced. Conversely, in other use applications, the IR window 3 may be left transparent to provide a consistent field of illumination. It may be understood that other implementations may include two or more controllable zones for allowing configuration to a greater variety of use applications. Accordingly, a configurable illuminator 1 may be provided which allows for the selective restriction of IR light in certain regions in a similar way to the second implementation, but without requiring the more complex cell-by-cell driving associated with a cellular IR window 3. Therefore, a lower cost implementation may be provided requiring fewer electrical signals and electric field conductor connecting lines.

[0030] With the above arrangements, the light flux emitted from the illuminator can be easily adjusted, thereby allowing a standardized illumination unit to be used for different systems, applications, and vehicle configurations. That is, the illuminators may be manufactured as a standard off-the-shelf component, and then simply adjusted using a controller depending on the specific application requirements. This thereby allows for the cost advantages of economies of scale.

[0031] In turn, the above also provides for a more targeted use of IR illuminators within the vehicle. For example, in the case of illuminating the rear passenger seats, rather than simply increasing the intensity of IR light emitted from a unit located in the front of the vehicle, a separate illuminator may be provided in the rear. This approach thereby avoids very high intensity IR light being emitted directly in front of the driver's eyes, and hence mitigates the potential risk of eye damage. At the same time, the IR light energy delivered to the area of rear seats is increased, allowing for improved sensor functionality.

[0032] Moreover, the ability to selectively adjust the intensity of IR light in different regions of the field of illumination also allows for target specific optimizations. For example, as described in relation to the third implementation, the intensity of IR light delivered to higher regions of the interior cabin, where a vehicle occupant's eyes are likely to be, may be reduced. At the same time, a greater intensity of IR light may be applied to lower regions of the interior cabin to enhance sensor detection in these regions. This customized illumination pattern may therefore improve the performance of, for instance, passengers seat analysis, while decreasing the overall illumination level to protect the vehicle occupants' eyes.

[0033] It may be understood that the implementations illustrated above shows an application only for the purposes of illustration. In practice, implementations may be applied to many different configurations, the detailed implementations being straightforward for those skilled in the art to implement.

[0034] For example, it may be understood that although in the above implementations the controller is described as being separate to the illuminator, in other implementations it may be integrated into the illuminator package. Equally, although the illuminator has been described as a separate unit to the IR camera, it may be understood that a combined assembly may be provided with both the illuminator and camera integrated into one unit.