A vehicle occupant safety system

Abstract

A vehicle occupant safety system 100 includes a display layer 124 and an in-vehicle monitoring device 102. The in-vehicle monitoring device includes an image sensor 106 and an image light source 108. The image sensor captures and generates one or more images. The image light source transmits light rays through the display layer. The in-vehicle monitoring device is displaced posterior to the display layer. The image light source includes an optical layer 112 having multiple microstructures 408. The optical layer is displaced anterior to the image light source. The optical layer may be displaced at a distance L from the image light source and may include a long pass optical filter. The distance L may be selected from a range of at least one to two times more than a size of an aperture of the image light source. The distance L may be between 6-20mm. Controlling a vehicle occupant safety system includes detecting an eye gaze of a vehicle occupant using this device. In response to detecting the eye gazing towards / away from a display direction of the vehicle occupant safety system, an eye gaze display algorithm 118 executes an instruction set on a processor 104 switching the display on / off.

Description

TECHNICAL FIELD

[001] This disclosure relates to a vehicle occupant safety system and in particular, a vehicle occupant safety system having an in-vehicle monitoring device embedded within an active display layer. CROSS REFERENCE TO RELATED APPLICATIONS

[002] This application claims the benefit of SG Provisional Application no.10202400068U, entitled “A VEHICLE OCCUPANT SAFETY SYSTEM” filed on 9 January 2024, SG Provisional Application no. 10202400067S entitled “A VEHICLE OCCUPANT SAFETY SYSTEM” filed on 9 January 2024 and SG Provisional Application no. 10202400071S entitled “AN EYE GAZE OLED DISPLAY CONTROL METHOD” filed on 9 January 2024. BACKGROUND

[003] Conventional in-vehicle monitoring systems in automotive industry uses in-vehicle cameras to track driver’s behaviour or status of driver to ensure vehicle occupants safety. To avoid driver’s distraction, in-vehicle cameras for driver monitoring systems and cabin monitoring systems are usually designed in a way such that the in-vehicle camera appears hidden from view. By way of an example, this can be done by hiding the in-vehicle camera within a vehicle display apparatus, which may resolve pain point of camera field of view (FOV) occlusion by steering wheel.

[004] A main challenge of designing in-vehicle monitoring systems is that there is a limitation to space availability at a cockpit of a motor vehicle and placement of the camera affects FOV of driver and / or cabin as explained above. To address such concerns, some automotive manufacturers explore embedding cameras in bezel or parts of housing of display devices. However, design conforms to space of display device housing. In addition, automotive manufacturers are increasingly adapting use of OLED display technologies in motor vehicles due to an advantage of producing high resolution, high contrast display image quality, especially for motor vehicle models targeted at price insensitive consumers. However, one of the biggest disadvantages of OLED technology is its relatively short life time, and display burn-in issues which may compromise its cost and performances of motor vehicles in the long run.

[005] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. SUMMARY

[006] A purpose of this disclosure is to ameliorate the problem as discussed above, by providing the subject-matter of the independent claims.

[007] In an aspect of this disclosure, a vehicle occupant safety system is disclosed. The vehicle occupant safety system may comprise a display layer and an in-vehicle monitoring device. The in-vehicle monitoring device may further comprise an image sensor and an image light source. The image sensor may be operable to capture and generate one or more images. The image light source may be operable to transmit light rays through the display layer of the vehicle occupant safety system. The in-vehicle monitoring device may be displaced posterior to the display layer and the image light source may comprise an optical layer having a plurality of microstructures. The optical layer may be displaced anterior to the image light source. An advantage of the aforesaid configuration is that the in-vehicle monitoring system is embedded within an active displaying area when in operation, thereby addressing space constraints in motor vehicle. More advantageously, the optical layer having a plurality of microstructures shapes the profile of light rays diverging towards the display layer. In all of the embodiments disclosed herein, the light rays from the light source are operating a near infrared (NIR) wavelength, thus the placement of an optical layer including a plurality of microstructures shapes the profile of NIR light rays diverging towards the display layer, to address adverse effects such as red glow effect or damage to a human eye. Even more advantageously, the selection of NIR shall fulfil U\SER class 1 for IEC60825-1, 2014, LASER standards, to satisfy legal regulations. In addition, selection of NIR light source or NIR LED shall also be designed to comply with IEC63268 and fulfil IEC62471 exempt risk group.

[008] In some embodiment, the optical layer may be displaced at a distance (L) from the image light source.

[009] In some embodiment, the distance (L) between the optical layer and the image light source may be selected from a range at least one to two times more than a size of an aperture of the image light source. In such embodiment, the distance between the optical layer and the image light source may be between 6mm to 20mm. In such embodiment, the optical layer may comprise a long pass optical filter. In such embodiment, the image light source may be operable at a wavelength ranging from 840nm to 900nm. In such embodiment, the image light source may be an IR LED chip.

[0010] In some embodiment, the distance (L) between the optical layer and the image light source may be selected from a range at least three times more than a size of an aperture of the image light source. In such embodiment, the distance between the optical layer and the image light source may be between 8mm to 18mm. In such embodiment, the image light source may be operable at a wavelength ranging from 800nm to 980nm. In such embodiment, the image light source may be a VSCEL chip.

[0011] In some embodiment, optical layer may be operable to diverge the light rays received from the image light source at least twice. The optical layer may be further operable to transmit the light rays diverged through the display layer.

[0012] In some embodiment, each of the plurality of microstructures of the optical layer has at least one curvature profile. The at least one curvature profile may be displaced on opposing end of each of the plurality of microstructures. In some embodiment, the at least one curvature profile may be a spherical curve. In some embodiment, the at least one curvature profile may be an aspherical curve.

[0013] In some embodiment, the optical layer may be curved. Henceforth, the optical layer is a curved optical layer with a plurality of curved microstructures.

[0014] In some embodiment, the optical layer may be optically bonded to at least a portion of the display layer. In some embodiment the optical layer may be held by a holder. In some embodiment, the holder may be made of plastic material. In some embodiment, the holder may be made of metal material. In some embodiment, the holder comprises a reflective housing.

[0015] In some embodiment, the image sensor may be operable to capture and generate one or more images in an infrared wavelength.

[0016] In some embodiment, the optical layer may be a micro lens array.

[0017] In an aspect of this disclosure, an eye gaze display control method is provided. The method may comprise detecting, by way of by way of an in-vehicle monitoring device, an eye gaze of a vehicle occupant. In response to detecting, by way of the in-vehicle monitoring device, the eye gaze of the vehicle occupant gazing towards the display direction, an eye gaze display algorithm executes, by way of a processor, a set of instructions to cause the display to switch ON. In response to detecting, by way of the in-vehicle monitoring device, the eye gaze of the vehicle occupant gazing away from the display direction, the eye gaze display control algorithm executes, by way of the processor, a set of instructions to cause the display to switch OFF. An advantage of this aspect of the disclosure is to address burn-in issues of OLED displays, by improving power consumption.

[0018] Other objects, features and characteristics, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification. It should be understood that the detailed description and specific examples, while indicating the non-limiting embodiments of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: FIG. 1 shows a system block diagram in accordance with a preferred embodiment. FIG. 2 shows a top view of a vehicle occupant safety system in accordance with this disclosure. FIG. 3 shows a far field configuration in accordance with this disclosure. FIG. 4 shows a side view of an in-vehicle monitoring device in accordance with this disclosure. FIG. 5 shows a top view of a vehicle occupant safety system in accordance with this disclosure. FIG. 6 shows a flowchart illustrating an eye gaze display control method. FIG. 7a-7b shows an exemplary embodiment of an eye gaze display control. DETAILED DESCRIPTION

[0020] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.

[0021] Hereinafter, the term “first”, “second”, “third” and the like used in the context of this disclosure may refer to modification of different elements in accordance with various exemplary embodiments, but not limited thereto. The expressions may be used to distinguish one element from another element, regardless of sequence of importance. By way of an example, “a first curvature profile” and “a second curvature profile” may indicate different curvature profile regardless of order or importance. On a similar note, a first curvature profile may be referred to as the second curvature profile and vice versa without departing from the scope of this disclosure.

[0022] The term “active displaying area” or “active region” shall refer to a portion of a display apparatus or a vehicle display apparatus which is meant for actively displaying a visual output when in operation.

[0023] The term “above”, below”, “top”, “bottom”, “upper”, “lower” and the like used in this section are used descriptively for the figures to assist the reader with understanding of this disclosure, and do not represent limitations on the scope of the disclosure, unless as defined by the appended claims.

[0024] The term "processor" used in the context herein should be interpreted broadly to encompass a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, and so forth. Under some circumstances, a "processor" may refer to an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc. The term "processor" may refer to a combination of processing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0025] FIG. 1 shows a block diagram of a vehicle occupant safety system 100. As shown in FIG. 1, the vehicle occupant safety system 100 may comprise an in-vehicle monitoring device 102, the in-vehicle monitoring device 102 may include an image sensor 106. A suitable type of image sensor 106 may be a global shutter infrared (IR) type image sensor. The image sensor 106 may include an imaging lens 110. The imaging lens 110 may include long pass optical filters. The in-vehicle monitoring device 102 may further comprises an image light source 108. The image light source 108 may be operable in a near infrared (NIR) wavelength. In some embodiment, suitable type of image light source 108 may be a verticalcavity surface-emitting laser (VCSEL), in particular, the image light source 108 may be VCSEL chip. In some embodiment, suitable type of image light source 108 may be an infrared light emitting diode (IR LED) device, in particular, the image light source 108 may be IR LED device or IR LED chip. The image light source 108 may comprise an optical layer 112. The optical layer 112 may include a plurality of microstructures 408 (FIG. 4 referred). The optical layer 112 may be displaced anterior to the image light source 108. In some embodiment, the optical layer 112 having a plurality of microstructure may be constructed using optically transparent material. In some embodiment, the optical layer 112 may be a micro lens array (MLA).

[0026] The vehicle occupant safety system 100 may comprise a display layer 124. A suitable type of display layer 124 may be OLED display layer, although not limited thereto. The in-vehicle monitoring device 102 may be displaced posterior to the display layer 124. The optical layer 112 may be displaced at a distance, L from the image light source 108. In some embodiment, the distance between the optical layer 112 and the image light source 108 may be at least one to two times more than a size of an aperture 302 (FIG. 3 referred) of the image light source 108. In some embodiment, the distance, L between the optical layer 112 and the image light source 108 may be at least three times more than a size of an aperture 302 of the image light source 108. The size of the aperture 302 of the image light source 108 may be defined by a diffuser opening size of the image light source 108.

[0027] The display layer 124 may include a under display camera (UDC) area 120, the UDC area 120 may be a predetermined location with a predefined pixel structure design to enable visible and NIR light rays to pass through the display layer 124. The structural configuration of the display layer 124 may include pixel control material on either inside or outside of this UDC area 120, pixel resolution adjustment and so forth. The structural configuration of the display layer permits transmittance of approximately 30% of NIR wavelength can reach up to -30% but not limited thereto. Henceforth, the It shall be understood by a skilled practitioner the image light source 108 may be driven by a driver circuit 114 to supply light rays towards the display layer 124 and the vehicle occupant safety system 100 may be powered by a power supply 116. A suitable type of display layer 124 may be an organic LED (OLED) display layer, of which such display layers 124 are operable to control each individual pixel.

[0028] In some embodiment, the vehicle occupant safety system 100 includes a host system on chip (SoC) to control the vehicle occupant safety system. An algorithm 118 for image post-processing may be included to execute vehicular applications such as driver monitoring, cabin monitoring, object detection, child left behind in vehicle, but not limited thereto.

[0029] Optionally, the vehicle occupant safety system 100 may include a cover glass 122, the cover glass 122 may be transparent at both visible lightwavelength for display function and NIR light wavelength for vehicular applications, it is typically used to support and protect the display layer with optical bonding 410 (FIG. 4 referred) to display layer 124.

[0030] Turning now to design consideration of the vehicle occupant safety system 100 disclosed herein, as explained above, the structural configuration of the display layer 124 may include a UDC area 120, thereby yielding the in-vehicle monitoring device 102 displaced posterior to the display layer 124. The structural configuration of the UDC area 120 permits light rays from the image light source 108 to pass through the display layer when the in-vehicle monitoring device is displaced posterior to the display layer. Henceforth, the total optical power transmitting through to the image sensor would be less than 30% as compared to a conventional display layer without UDC area structural configuration.

[0031] When the image sensor 106 and the image light source 108 are embedded posterior to the display layer 124, light rays from the image light source 108 passes through the display layer 124 twice. In order words, the light rays from the image light source 108 diverge at least two times, on a system level. Consequently, the total optical power reach to the image sensor 106 would be less than 10% as compared to without structural configuration of the UDC area 120.

[0032] Such optical power increase can be achieved by option of increase operation point of the image light source 108 or image light source 108 driver circuit. The operation point may include setting image light source 108 power on pulse duration, pulse on driving current, and pulse frequency, etc.

[0033] In contrast with conventional display layers without UDC area 120 structural configuration, such optical power operation point increase would cause many significant effects. The two most critical effects would be the red glow effect and the human eye safety hazard due to extra optical power. Also, the number of image light source 108 driver circuit increase would cause significant impact on a system level, which includes to the power consumption, thermal management issues, noise performance and cost of the product, etc.

[0034] A main advantage of this disclosure is to present an in-vehicle monitoring device embedded within a display layer, of which the display layer is an active displaying layer or active displaying region when in operation, such that the in-vehicle monitoring device is operable to sense and capture images of at least one vehicle occupant onboard a motor vehicle, yet at the same time, the display layer is displaying contents or information. Further, to ensure safety of human eyes, the selection of NIR light source shall fulfil LASER class 1 for IEC60825-1, 2014, LASER standards, to satisfy legal regulations. In addition, selection of NIR light source or NIR LED shall also be designed to comply with IEC63268 and fulfil IEC62471 exempt risk group. To address red glow effect and ensure human eye safety, the subject disclosure proposes an optical layer having a plurality of microstructures, the optical layer displaced anterior to the image light source. The aforesaid configuration achieves even distribution of light rays amongst different retinal cells to counter red glow effect and eye safety while maintaining or improving the illumination profile and irradiance at objective plane.

[0035] More advantageously, this disclosure attempts to at least ameliorate the challenge of designing in-vehicle monitoring systems embedded within an active display region, of which the selection of suitable wavelength for light source to capture images with sufficient sensitivity suitable for post-processing, to make sense of images captured. This is crucial for determination of whether the driver is sleepy or distracted, and determination of objects and / or passengers such as child left behind in-vehicle. A known selection of suitable wavelength is near-infrared (NIR) active lighting. However, a drawback of using NIR active lighting is optical power loss through vehicle display apparatus, in particular digital vehicular OLED (Organic Light-Emitting Diode) displays, where a camera operating from behind the display camera also known as an UDC area which typically transmit 20% to 30% of NIR light optical power. The amount of lighting will not allow in-vehicle monitoring systems to capture high resolution images.

[0036] Nonetheless, working range of NIR wavelength has its own drawbacks, especially when implemented in consumer products such as motor vehicles. NIR wavelength falls within a range of 850nm or 940nm which is invisible to human eyes. However, under certain condition, the NIR light emitted by a light source such as may still be perceived as a red glow by human eyes. This is commonly known as a red glow effect. This effect can be a severe distraction or confusing fault indication to vehicle occupants. Red glow effect may cause discomfort to the user or driver, and it is a well-known inherent problem of NIR illumination systems. To ensure safety of human eyes, as under normal condition, NIR wavelength operates at a range of 800nm - 1000 nm. The major retinal thermal hazard needs to be considered, which is related to the angular subtense or size of the light source.

[0037] FIG. 2 shows a top view of a vehicle occupant safety system in accordance with this disclosure. Shaping Illumination

[0038] An object of the optical layer 112 may be to shape the expected illumination profile with good homogeneity and optical efficiency. The optical layer 112 includes a plurality of microstructures 408 as shown on FIG. 4, each of the plurality of microstructures 408 output angle may be operable to achieve illuminating a targeted range, as shown in FIG. 2. Each of the plurality of microstructures 408 has at least one curvature profile. In some embodiment, each of the plurality of microstructures 408 may include two curvature profiles, such that each of the at least one curvature profile may be displaced on opposing end of each of the plurality of microstructures 408. By way of an example, a first at least one curvature profile may be displaced at a top surface of a microstructure 408 and a second at least one curvature profile may be displaced at a bottom surface of the microstructure 408, but not limited thereto. The at least one curvature profile may be a spherical curve or an spherical curve. Far Field Configuration

[0039] Referring to FIG. 3 which shows a far field configuration, it can be observed the optical layer 112 is displaced at a distance, L from the image light source 108.

[0040] In some embodiment, the distance, L may be at least one to two times larger than the size of the aperture 302 as shown on FIG. 3. By way of an example, in an embodiment using IR LED chip having dome lens with a diameter of 2 mm, the minimum distance would be 2-4mm, and preferred distance may be around 6mm to 20mm. The overall X / Y dimension can be calculated based on IRLED field of illumination (FOI) angle with design considerations accordingly.

[0041] The optical layer may be operable to collimate the light rays received from the image light source and transmit the light rays collimated through the display layer.

[0042] The optical layer housing inter surface may be reflective, through e.g. surface polishing with aluminium material, if IR LED chip nature field of illumination different from housing open, then the housing can be used as reflector for further illumination profile adjustment. Such housing when build with metal material can also be designed to serve as a heat sink for better thermal management.

[0043] In some embodiment, where the light source uses VSCEL chip, the distance, L between the optical layer 112 and the image light source 108 may be at least three times more than a size of an aperture 302 (FIG. 3 referred) of the image light source 108. The distance, L between the optical layer 112 and the image light source 108 may be between 8mm to 18mm.

[0044] The optical layer 112 may be operable to diverge the light rays received from the image light source 108 and transmit the light rays diverged through the display layer 124.

[0045] The optical layer 112 housing 202 inner surface may be reflective, through e.g. surface polishing with aluminium material, for example a VCSEL chip or an IR LED chip nature field of illumination may be different from housing opening, then the housing can be used as reflector for further illumination profile adjustment. Such housing when build with metal material can also be designed to serve as a heat sink for better thermal management.

[0046] In some embodiments as disclosed herein, the optical layer 112 may be curved, where the entire optical layer 112 is a curved surface with a plurality of microstructures, each of the plurality of microstructures having a curvature profile, details of which will be discussed further below. Countering Red Glow Effect

[0047] Human eye photoreceptor cells’ sensitivity to NIR light is dependent on the light irradiance reaching each photoreceptor cell and the associated wavelength. The human eye can perceive the NIR light if the irradiance is above a certain threshold depending on its wavelength.

[0048] Referring to FIG. 2, the optical layer 112 may be able to distribute the light source’s radiant flux evenly among the larger surface of the optical layer 112, significantly increased the viewable area of apparent source thus reduced radiance from the surface of the optical layer 112, in that reduced the irradiance to human eye per photoreceptor 212.

[0049] Additionally in order to achieve such a significant level of reduction that a lower wavelength as 850nm / 880nm can be used, would expect the optical layer 112 working at far field with relatively larger area. Also, it is important that each microstructure 408 output angle aim to the targeted full area of objective plan, so that smaller portion of radiant flux emitted from each singlet reach to the eye retinal per photoreceptor cell 212, thus effectively reduce the red glow effect. Countering Eye Damage by Laser

[0050] For normal operation condition: at NIR wavelength 800nm-1000nm range, the major retinal thermal hazard considered, in general, because of human eye projection model, refer to FIG.4, with the MLA design disclosed herein by the inventor, such that radiant flux evenly distributed to more human eye retinal photoreceptor cells, the lower thermal hazard per retinal cell.

[0051] The optical layer is able to distribute the light source’s radiant flux evenly among the larger surface of the optical layer, significantly increased the angular subtense of the apparent source, thus significantly reduced eye safety risk. In some embodiment where the light source is an IR LED chip, the cause of risk to eye safety may be directed to human eye cornea. In some embodiment where the light source is a VCSEL, selection of VSCEL may lead to LASER safety risk. Single Fault Condition - VSCEL

[0052] Following IEC60825-1 2014, the LASER safety evaluation need to include reasonable single fault conditions. In that one general single fault of the Image light source would be its diffuser shear off or crack, such failure would cause the VCSEL die emitting with its nature FOI of around + / -5-10 degree, which is much narrower angle as compared to with diffuser, significantly increased the human eye safety risk of retinal thermal hazard.

[0053] However, in the solution provided herein, optical layer 112 which can also serving as the second level diffuser, that without Image light source diffuser, the final field of illumination (FOI) will still be similar to the original designed FOI, thus reduced the human eye safety risk to normal working condition. A simulation of such failure mode has been conducted, that the final vertical FOI of ~30-degree, horizontal FOI of ~40-degree, are similar to original design as expected. Countering Speckle Noise - VSCEL

[0054] In some embodiment where image light source 108 may be a LASER, speckle noise created may affect the image quality, this is caused by LASER light interference. With optical layer 112, such speckle noise will be smoothed with multiple LASER sources re-projection. In-Vehicle Monitoring Device

[0055] In some embodiment, the optical layer 112 may be optically bonded to at least a portion of the display layer 112. The at least a portion may be defined by the UDC area 120. An optically transparent adhesive may be used to optically bond the optical layer 112 to the display layer 124.

[0056] Referring to FIG. 4 which shows a side view of the in-vehicle monitoring device 102, the optical layer 112 may be held by a holder to hold the optical layer 112. In some embodiment, the holder may be made of plastic material. In some embodiment, the overall transmittance may be improved by removing any air gap caused extra surface reflection between the display layer 124 and the image light source 108.

[0057] In some embodiment, the holder may be made of metal material. In this embodiment, the holder may also be used as a heat sink for thermal management purpose.

[0058] FIG. 5 which shows a top view of a vehicle occupant safety system 100 in accordance with this disclosure, in some embodiment, the image light source 108 may be VSCEL device or chip, which is a LASER component. In some embodiment, the image light source may be IR LED device or IR LED chip. Such image light source 108 may include a diffuser, a housing and a bare die. The image light source 108 may also include a diffuser failure detection feature.

[0059] Optical layer 112 may be glass material or plastic material, or polymer materials, etc. Optical layer 112 be manufactured with for example, injection moulding process to achieve cost efficiency.

[0060] The optical layer 112 may include a top surface profile curvature, for easy optical bonding or fitting purpose. The optical layer 112 may also be coated with an optical coating such as anti-reflection coating and / or optical long pass filter coating and so forth.

[0061] The optical layer 112 may include a bottom surface where the plurality of microstructures 408 are distributed. By way of example the curvature profile may be multiple line linear curvature or spherical curvature or aspherical curvature. The selection of suitable curvature profile may achieve an overall illumination profile adjustment to fit to targeted field of illumination and to create uniformed illumination.

[0062] For each of the plurality of microstructure 408 of the optical layer 112, it may be spherical or aspherical curvature surface or profile, as described above. In some embodiment, the curvature profile is a hyperbolic profile. A hyperbolic profile yields better red glow reduction and illumination homogenously as compared with other types of curvature profile. Each of the plurality of microstructure 408 of the optical layer may be diverging or converging surface.

[0063] The X / Y dimension may be different to create a desired illumination profile in accordance with design specification such that different vertical FOI (field of illumination) and horizontal FOI can be achieved.

[0064] Size of each curvature profile may be as small as to the human eye diffraction limit to achieve maximum red glow reduction and eye safety performance.

[0065] Each microstructure 408 tunes the light rays with its illumination profile. In some embodiment, an angle of the light rays covers wide illumination angle. In some embodiment, an angle of the light rays covers narrow illumination angle.

[0066] The optical layer 112 overall X / Y dimension and distance to image light source 108 is important, in general large dimension and distance is preferred in order to get better red glow reduction and eye safety performance. For far field configuration, would expect the distance at least around three times larger than the size of the image light source 108 diffuser X / Y or diameter dimension, for e.g. with diffuser size of 2x2 mm, the minimum distance would be 6mm, and preferred distance can be around 8-18mm, and the optical layer 112 overall X / Y dimension can be calculated based on image light source 108 FOI angle with design considerations accordingly.

[0067] The display layer 124 with UDC area 120 has a low transmittance rate at approximately ~30%, hence would be beneficial to achieve red glow reduction, and reduce LASER emitting intensity thus better for eye safety for each single image light source 108 device.

[0068] Further, by increasing nearby UDC area 120 brightness, would according to human eye behaviour, e.g. reduce the eye pupil size, thus could also reduce the red glow effect.

[0069] With above mentioned parameters tuned, the red glow reduction can come to a level that an 850nm or 880nm image light source 108 with optical layer 112 can be comparable with a 940nm image light source 108 without optical layer 112. The lower working wavelength solution is suitable for in-vehicle applications.

[0070] From the result can observe the maximum radiance reduced for around more than 20 times, which may correspond to -100+ times red glow reduction based on human eye sensitivity.

[0071] Radiance value is a good indicator to human eye sensitivity related red glow effect and eye safety retinal thermal hazard. The relation ratio between radiance and human eye sensitivity under certain conditions can be established with further research study.

[0072] FIG. 6 shows a flowchart illustrating an eye gaze display control method 600 for a vehicle occupant safety system as disclosed herein. The method 600 may comprises at step 602, detecting, by way of an in-vehicle monitoring device, an eye gaze of a vehicle occupant. In some embodiment, in response to detecting, by way of the in-vehicle monitoring device, the eye gaze of the vehicle occupant gazing towards a display direction, an eye gaze display algorithm executes, by way of a processor, a set of instructions to cause the display to switch ON at step 604. In some embodiment, in response to detecting, by way of the in-vehicle monitoring device, the eye gaze of the vehicle occupant gazing away from the display direction, the eye gaze display control algorithm executes, by way of the processor, a set of instructions to cause the OLED display to switch OFF at step 606. Beneficially, the display of the vehicle occupant safety system is controlled using eye gaze of a vehicle occupant.

[0073] FIG. 7a - 7b shows an exemplary embodiment of an eye gaze display control. Referring to FIG. 7a, a driver or a vehicle occupant 704 has an eye gaze direction looking away from the display layer 124. In response to the in-vehicle monitoring device 102 detects eye gaze of the vehicle occupant 704 gazing away from the display direction, i.e. the eye gaze direction 706, an eye gaze control algorithm may be executed to switch OFF the display. Conversely as shown in FIG. 7b, in an event where the in-vehicle monitoring device 102 detects eye gaze direction 706’of the vehicle occupant gazing towards the display direction, an eye gaze control algorithm may be executed to switch ON the display layer 124.

[0074] Thus it can be seen, a vehicle occupant safety system comprising an optical layer having a plurality of microstructures, the optical layer displaced anterior to the light source has the advantage of countering red glow effect, and human eye safety. The system disclosed also addresses single fault conditions to follow I EC standard. So that at system level can design suitable operation point of VCSEL chip and the number of VCSEL chips required to fulfil the expected design configuration with expected performance.

[0075] Furthermore, at least within automotive industry, in-vehicle monitoring devices has been adopting a working wavelength of 940nm instead of 850nm due to the fact that red glow effect would be much lower at longer wavelength because of human eye sensitivity drop exponentially with wavelength increase. While with our proposed solution, the red glow effect can be reduced to such a significance that its red glow effect reaches to an acceptable level, that lower working wavelength such as 850nm or 880nm so on and so forth, could already be used at system level design.

[0076] The advantage of such lower working wavelength would be that the common silicon-based image sensor’s quantum efficiency thus the sensitivity would increase significantly. Increased sensitivity may achieve image quality / image brightness, with a lower overall system optical power. In that e.g. the number of VCSEL chip or IR LED could also be reduced by at least half, depends on the selected image sensor’s QE ratio between 850nm / 880nm and 940nm, with benefits of reducing size / power / thermal / noise impacts and large cost saving of the product. Such advantage can also be used to adjust VCSEL device’s operation point to achieved expected design performance.

[0077] It should further be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, operation or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements and 5 method of operation described in the exemplary embodiment without departing from the scope of the disclosure as set forth in the appended claims. List of Reference Signs 10 100 System block diagram 102 In-vehicle monitoring device 104 Processor 106 Image sensor 108 Image light source 110 Imaging lens 112 Optical layer or Micro lens array (MLA) lens 114 Driver circuit 116 Power supply 118 Algorithm 120 UDC area 122 Cover glass 124 Display layer 200 Top view of vehicle occupant safety system 202 Housing 204 Object plane 206 Eye 208 Eyeball 210 Eye lens 212 Retina photoreceptor cells 214 MLA lens microstructure angle 300 Far Field Configuration 302 Aperture 304 Die L Distance Side view of in-vehicle monitoring device Image light source housing Image light source diffuser MLA lens holder MLA microstructure Optical bonding Top view of vehicle occupant safety system Method Detecting an eye gaze switch ON display when eye gazing towards display direction switch OFF display when eye gazing away from display direction exemplary embodiment of an eye gazing away from display direction exemplary embodiment of an eye gazing towards display direction Calibration point Vehicle occupant Eye gaze direction

Claims

1. A vehicle occupant safety system (100) comprising: a display layer (124);andan in-vehicle monitoring device (102), the in-vehicle monitoring device (102) comprises:an image sensor (106), the image sensor (106) operable to capture and generate one or more images;andan image light source (108), the image light source (108) operable transmit light rays through the display layer (124),whereinthe in-vehicle monitoring device (102) is displaced posterior to the display layer (124);andthe image light source (108) comprisesan optical layer (112) having a plurality of microstructures, the optical layer (112) displaced anterior to the image light source (108).

2. The system (100) according to claim 1, wherein the optical layer (112) is displaced at a distance (L) from the image light source (108).

3. The system (100) according to claims 1-2, whereinthe distance (L) between the optical layer (112) and the image light source (108) is selected from a range:• at least one to two times more than a size of an aperture (302) of the image light source (108).

4. The system (100) according to claims 1-3, wherein the distance (L) between the optical layer (112) and the image light source (108) is between 6 mm to 20mm.

5. The system (100) according to claim 4, wherein the optical layer (112) comprises a long pass optical filter.

6. The system (100) according to claims 1 to 5, wherein the image light source (108) is operable at a wavelength ranging from 840nm to 900nm.

7. The system (100) according to claims 1-6, wherein the image light source (108) is an IR LED chip.

8. The system (100) according to claims 1 - 2, whereinthe distance (L) between the optical layer (112) and the image light source (108) is selected from a range:• at least three times more than a size of an aperture (302) of the image light source (108).

9. The system (100) according to claims 1-2 and 8, wherein the distance (L) between the optical layer (112) and the image light source (108) is between 8 mm to 18mm.10.The system (100) according to claims 1, 2, 8 - 9, wherein the image light source (108) is operable at a wavelength between 800nm to 980nm.

11. The system (100) according to claims 1, 2, 8 - 10, wherein the image light source (108) is a VSCEL chip.

12. The system (100) according to claims 1 - 7 or claims 1, 2, 8 -11, wherein the optical layer (112) is operable todiverge the light rays received from the image light source (108) at least twice;andtransmit the light rays diverged through the display layer (124).

13. The system (100) according to any one of the preceding claims, wherein each of the plurality of microstructures (408) of the optical layer (112) has at least one curvature profile.

14. The system (100) according to claim 13, wherein the at least one curvature profile is displaced on opposing end of each of the plurality of microstructures (408).

15. The system (100) according to any one of the preceding claims, wherein the at least one curvature profile is:- a spherical curve;or- an aspherical curve.

16. The system (100) according to any one of the preceding claims, wherein the optical layer (112) is curved.

17. The system (100) according to any one of the preceding claims, wherein the optical layer (112) is optically bonded to at least a portion of the display layer (124).

18. The system (100) according to any one of the preceding claims, wherein the optical layer (112) is held by a holder.

19. The system (100) according to claim 17, wherein the holder is made of plastic material.

20. The system (100) according to claim 17, wherein the holder is made of metal material.

21. The system (100) according to claim 17, wherein the holder comprises a reflective housing (202).

22. The system (100) according to any one of the preceding claims, wherein the image sensor (106) is operable to capture and generate one or more images in an infrared wavelength.

23. The system (100) according to any one of the preceding claims, wherein the optical layer (112) is a micro lens array.

24. A method (600) of controlling a vehicle occupant safety system (100), the method (600) comprising:detecting (602), by way of an in-vehicle monitoring device as defined in accordance with any one of claims 1 to 23, an eye gaze of a vehicle occupant;in response to detecting, by way of the in-vehicle monitoring device, the eye gaze of the vehicle occupant gazing towards a display direction of a vehicle occupant safety system, an eye gaze display algorithm executes (604), by way of a processor, a set of instructions to cause the display to switch ON.

25. The method (600) according to claim 24, characterised by thatin response to detecting, by way of the in-vehicle monitoring device, the eye gaze of the vehicle occupant gazing away from the display direction of the vehicle occupant safety system, the eye gaze display control algorithm executes (606), by way of the processor, a set of instructions to cause the display to switch OFF.

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