Patent Application
20230356654
This U.S. patent application claims the benefit of GB patent application No. 2206528.8, filed May 5, 2022, which is hereby incorporated by reference.
This disclosure relates to a motor vehicle, in particular cabin sensing system for a motor vehicle.
Automotive industry experiences a trend of implementing driver monitoring systems (DMS) to ensure safety of drivers. The most common function of DMS is to monitor status of driver, to determine whether the driver is fatigue, drunk or in a state fit for operating a motor vehicle, to achieve driver's and road users' safety.
Designing an effective DMS is often challenging, as more and more information is required to determine facial characteristics of drivers. One of the methods to counter this problem is to capture images of the driver within an infrared wavelength to obtain images of the driver for facial recognition image processing. A typical working IR wavelength is invisible to human's eyes.
Nonetheless, under certain conditions, for example at low ambient lighting condition, such as an interior environment of a passenger cabin, light rays emitting within IR wavelength may be detected by a human's eye and the light rays will be perceived as a red glow, also known as a red glow effect. This red glow of light may cause distraction to a driver operating the motor vehicle, thus causing discomfort, and compromising safety of the driver.
There is therefore a need to provide a motor vehicle sensing system that overcomes, or at least ameliorates, the problems described above. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taking in conjunction with the accompanying drawings and this background of the disclosure.
A purpose of this disclosure is to ameliorate the problem of red glow effect being detected by human's eye for safety by providing the subject-matter of the independent claims.
The objective of this disclosure is solved by a motor vehicle cabin sensing system, which comprises an image sensor operable to capture one or more images, the image sensor having a field of view of a motor vehicle cabin, an illumination source operable to transmit light rays towards the motor vehicle cabin, and an illumination lens array operable to diffuse the light rays emitting from the illumination source towards the motor vehicle cabin. The illumination lens array further comprises two or more single lens element, each of the two or more single lens element operable to diffuse the light rays emitting from the illumination source to one or more photoreceptor cells of a retina, wherein each of the two or more single lens element is operable to detect a radiant intensity representing a red glow, and wherein the radiant intensity is 0% to 50% of the light rays emitting from the illumination source.
The above-described aspect of this disclosure yields a motor vehicle cabin sensing system which solves the problem of red glow effect being perceived by a driver, which causes distraction. The problem of red glow effect is solved by reducing a radiant intensity of the red glow detected by one or more photoreceptor cells of a human's eyes by 10 to 100 times. For example, the radiant intensity is reduced to 0% to 50% of the light rays emitting from the illumination source, in response to the diffusing of light rays using an illumination lens array. For example, the radiant intensity is reduced to 0.1% to 30% of the light rays emitting from the illumination source, and even more preferably, the radiant intensity is reduced to 1% to 10% of the light rays emitting from the illumination source.
In an embodiment of a system as described above, the illumination lens array is positioned forward of the illumination source.
The above aspect of this disclosure is to provide an optical way to diffuse light rays emitting from the illumination source such that the light rays transmitting towards the motor vehicle cabin are incident rays received by one or more photoceptor cells of the retina of a human's eye.
In an embodiment of a system as described above, the illumination lens array comprises two or more single lens elements integrated on a single lens sheet.
The above aspect of this disclosure is to allow flexibility in design of the illumination lens array, such that each single lens element may be resized according to system requirements. For example, the total number of lens element depends on the overall lens array size. Nonetheless, there is no constraint as to the number of lens. However, a higher number of lens element will yield an improved or better performance in terms of red glow effect reduction detected by the retina.
In an embodiment of a system as described above, the illumination lens array is a micro lens array.
The above aspect of this disclosure is to provide an alternative solution by replacing the single sheet illumination lens array with a micro lens array. Using micro lens array as the illumination lens array enables distribution of light rays evenly amongst the different lens array, thus achieving significant reduction of a radiant intensity perceived by the one or more photoreceptor cells.
In an embodiment of a system as described above, the illumination lens array is a is a Fresnel lens.
The above aspect of this disclosure is to provide an alternative solution by replacing the illumination lens array with a Fresnel lens array to achieve reduction in thickness of lens array, thereby yielding a much more compact system.
In an embodiment of a system as described above, each of the two or more single lens element further comprises a prism, a diverging lens, or a combination thereof.
The above aspect of this disclosure is to provide lens elements on a single sheet of lens array, to diffuse light rays from the illumination source of the motor vehicle cabin sensing system for diffusing light rays emitting from the illumination source such that only 0% to 50% of a radiant intensity is detected and transmitted through the one or more lens element. For example, the lens array may use a prism, a diverging lens or a combination of both a prism and a diverging lens to yield desired technical results.
In an embodiment of a system as described above, the illumination source comprises a near infrared (NIR) illumination source.
The above aspect of this disclosure is to defines a type of illumination sourced used in the motor vehicle cabin sensing system, to achieve an infrared working wavelength.
In an embodiment of a system as described above, the illumination source is a NIR light emitting diode (LED).
The above aspect of this disclosure is to defines an alternative type of illumination sourced used in the motor vehicle cabin sensing system, to achieve an infrared wavelength.
In an embodiment of a system as described above, the illumination source is a vertical-cavity surface-emitting laser (VCSEL).
The above aspect of this disclosure is to defines an alternative type of illumination sourced used in the motor vehicle cabin sensing system, to achieve an infrared wavelength.
In an embodiment of a system as described above, the system further comprises a reflective panel.
The above aspect of this disclosure is to yield light efficiency by reducing light leakage. This technical feature is useful for light sources with a wider view angle and addresses problem of light flux leakage from the sides of the illumination lens array caused by wide view angle. An example of a reflective panel may be a flat plate with reflective surface or a flat reflective mirror.
In an embodiment of a system as described above the reflective panel further comprises a first end and a second end, wherein a first end of the reflective panel is displaced adjacent to the illumination light source, and a second end of the reflective panel is displaced adjacent to the illumination lens array.
The above aspect of this disclosure is to yield an arrangement of the reflective panel which addresses problem of light flux leakage from the sides of the illumination lens array caused by wide view angle.
In an embodiment of a system as described above, the image sensor is operable within a near infrared (NIR) wavelength.
The above aspect of this disclosure is to define a type of image sensor suitable for implementation in a motor vehicle cabin sensing system as disclosed herein. Preferably, a basic image sensor is expected to work in NIR wavelength for driver monitoring system or cabin monitoring system without departing from the main inventive concept of this disclosure.
In an embodiment of a system as described above, the illumination lens array has a dimension of preferably 0.1 cm to 10 cm (1 mm-100 mm), more preferably 5 cm to 9 cm (50 mm to 90 mm) and even more preferably 0.1 to 0.2 cm (1 mm to 2 mm).
The above aspect of this disclosure is to provide a preferred dimension of the illumination lens array suitable for driver monitoring or cabin sensing systems. For example, the maximum size shall not exceed 5 cm to 10 cm to ensure such motor vehicle cabin sensing systems are able to support eye gaze tracking purposes. However, the main concept of the configuration of a dimension of the illumination lens array is to match the field of illumination of the illumination source at a distance, i.e., from an imaging module of the system to a position of human's eyes. Therefore, depending on distance between driver and illumination source, the minimum size of the illumination lens array may be higher, for example 2 mm in diameter which may match the size of light source but may vary higher or smaller in size, without departing from the main inventive concept.
In an embodiment of a system as described above, the radiant intensity detected by each of the two or more single lens element is preferably 0% to 50% of the light rays emitting from the illumination source, more preferably 0.1% to 30% of the light rays emitting from the illumination source, and even more preferably 1%-10% of the light rays emitting from the illumination source.
The above aspect of this disclosure is to yield a motor vehicle cabin sensing system which solves the problem of red glow effect being perceived by a driver, which causes distraction. For example, the radiant intensity is reduced to 0% to 50% of the light rays emitting from the illumination source, in response to the diffusing of light rays using an illumination lens array. For example, the radiant intensity is reduced to 0.1% to 30% of the light rays emitting from the illumination source, and even more preferably, the radiant intensity is reduced to 1% to 10% of the light rays emitting from the illumination source.
The objective of this disclosure is solved by a method of reducing red glow effect caused by an illumination source emitting light rays from a motor vehicle cabin sensing system, the method comprising capturing, by way of an image sensor, a field of view of a motor vehicle cabin, emitting, by way of an illumination source, light rays towards the motor vehicle cabin, and diffusing, by way of an illumination lens array, the light rays emitting from the illumination source towards the motor vehicle cabin, wherein the illumination array comprising two or more single lens element, wherein in response to the light rays emitting from the illumination source being diffused by the two or more single lens element, detecting, by way of each of the one or more single lens element, a radiant intensity representing a red glow, wherein the radiant intensity is 0% to 50% of the light rays emitting from the illumination source.
The above-described aspect of this disclosure yields a method which solves the problem of red glow effect being perceived by a driver caused by illumination from a motor vehicle cabin sensing system. The problem of red glow effect is solved by reducing a radiant intensity of the red glow detected by one or more photoreceptor cells of a human's eyes by 10 to 100 times. For example, the radiant intensity is reduced to 0% to 50% of the light rays emitting from the illumination source, in response to the diffusing of light rays using an illumination lens array. For example, the radiant intensity is reduced to 0.1% to 30% of the light rays emitting from the illumination source, and even more preferably, the radiant intensity is reduced to 1% to 10% of the light rays emitting from the illumination source.
Other objects and aspects of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings in which:
In various embodiments described by reference to the above figures, like reference signs refer to like components in several perspective views and/or configurations.
The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the disclosure or the following detailed description. It is the intent of this disclosure to present a motor vehicle cabin sensing system and method which is operable to reduce a radiant intensity of red glow effect received by a retina, by 0% to 50% of a radiant intensity of the illumination source used in the system disclosed.
For clarity and brevity, the host controller 120 include a processing unit 116 with a set of instructions stored thereon to execute functions of the system 100 and may optionally include an analyser module 118 for processing images captured by the image sensor 104. It shall be understood by a skilled practitioner the aforesaid features of the host controller 120 is a complementary feature which enhances the overall system 100 and removal of host controller 120 does not affect the main inventive concept of this disclosure.
In the embodiments discussed herein, the total size of illumination lens array range for cabin sensing systems such as driver's monitoring application or cabin monitoring applications, the size limit shall not to exceed e.g., 5-10 cm in diameter. The aforesaid dimension is for example to support eye gaze tracking functions. Apart from the aforesaid consideration, the dimension of the illumination lens array is based upon matching of the field of illumination of the illumination source at a distance. The minimum size shall be higher than the size of illumination source, e.g., typically −2 mm in diameter, but it is also possible to be of a different size, either bigger or smaller. Accordingly, the illumination lens array has a dimension of preferably 0.1 cm to 10 cm (1 mm-100 mm), more preferably 5 cm to 9 cm (50 mm to 90 mm) and even more preferably 0.1 to 0.2 cm (1 mm to 2 mm).
In all the above embodiments, suitable types of illumination sources may include any form of light sources suitable for working in an infrared wavelength range, for example a near infrared (NIR) illumination source, a NIR light emitting diode (LED) or a vertical-cavity surface-emitting laser (VCSEL).
Further, in all of the above embodiments, the radiant intensity detected by each of the two or more single lens element is preferably 0% to 50% of the light rays emitting from the illumination source. More preferably, the radiant intensity may reach as low as substantially zero percent, for example 0.1% to 30% of the light rays emitting from the illumination source and even more preferably 1%-10% of the light rays emitting from the illumination source.
Thus, it may be seen a motor vehicle cabin sensing system and method having an advantage of reducing a radiant intensity of red glow effect received by a retina, by 0% to 50% of a radiant intensity of an illumination source has been provided. While embodiments have been presented in the foregoing detailed description of the disclosure, it should be appreciated that a vast number of variation exist.
It should further be appreciated that the 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 embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements and method of operation described in the embodiment without departing from the scope of the disclosure as set forth in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2206528.8 | May 2022 | GB | national |
